Subject: MSX2 Compatible Computer Project Posted by Sergey on Tue

Subject: MSX2 Compatible Computer Project Posted by Sergey on Tue, 23 Jan 2018 21:12:41 GMT View Forum Message <> Reply to Message Hi,

I'd like to build an MSX2 compatible computer. I'd like to share some of my ideas, and to get opinion of the forum members.

My goals/wishes for this project: Follow MSX/MSX2 standards as close as possible 128 KiB (or more) RAM Yamaha V9938 VDP, 128 KiB Video RAM, composite and component outputs, with optional RGB output (header) The main purpose would be running MSX/MSX2 games. With CP/M, FUZIX, possibly MSX-DOS support being the secondary goal Two cartridge slots for game cartridges and hardware add-ons (e.g. MSX music, disk controller) Use CBIOS Implement a real keyboard. Likely using Cherry MX keys, and standard keycaps (a microcontroller based PS/2 adapter would be a backup option)

Design modularity and form factor options (which one would you prefer?): A single board with the entire computer implemented on it. Should be about 200 mm x 160 mm in size. Pros: most compact way, Cons: no modularity at all ECB based system. We already have an MSX (not MSX2) video board, that might somewhat help with developing this project, although a new V9938 based board would have to be implemented. Pros: individual boards can be used for other (non MSX) ECB systems. Cons: more expensive: DIN 41612 connectors, additional bus buffers, etc. Also not as compact Non-ECB backplane based system. Potentially built using 100 mm x 100 mm boards. Pros: cheaper than ECB, no need to adhere to ECB standard, can use some pins for MSX-specific signals (slot select, chip selects). Cons: well, not an ECB Hybrid approach: Main board with CPU, 8255 (slot select, keyboard), I/O decode, sound/joystick, etc. Memory daughter board with SRAM and Flash and memory mapping/paging logic. And a video daughter board. Pros: modular enough, easier debug, a possibility of an upgrade path. For example it include TMS9918, V9938, and perhaps V9958 VDP; or MSX (no paging memory) and MSX2 (paging in slot 3).

Storage devices: Floppy disk controller: include on board, or implement as a separate cartridge? Storage: Flash disk (e.g. built using 39SF040), CF, or SD? Perhaps it is possible to implement some kind of flexible cartridge emulation?

Thanks, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by danwerner on Tue, 23 Jan 2018 22:55:21 GMT View Forum Message <> Reply to Message

Page 1 of 148 ---- Generated from RetroBrew Computers Forum You might take a look a the S-100 archives -- there was some work to put together a MSX system on S-100 cards. S-100 has a pretty high entry point (with the power and card cage requirements), so I am not suggesting that is the way to go, but there is some work there that might be inspirational . . . . .

For me, I prefer a modular design -- it is easier to debug and the modules can be used for other projects which can lead to very interesting possibilities.

Dan

Subject: Re: MSX2 Compatible Computer Project Posted by mscane on Wed, 24 Jan 2018 00:39:17 GMT View Forum Message <> Reply to Message Hi Sergey,

That sounds like a really interesting project.

Maybe an alternative could be to refresh the N8 design with some updates ( https://www.retrobrewcomputers.org/doku.php?id=boards:sbc:n8 :n8 Replace the existing TMS9918 video with a V9938 chip (that would give 80x25 video I believe)Replace the 8255 keyboard interface with an 8242 PS/2 controller (like in the VGA3)Change the compact flash interface to a bus connected IDE (in 8 bit mode)Use an ATX style power connector The N8 also included a floppy interface, SD card and sound chip.

Perhaps you could also consider changing the form factor to match one of the PC standards such as a Mini ITX (17 x 17 mm) or Micro ATX (224 x 224 mm). That would allow you to use a wide range of ready made cases and power supply options.

I'm not sure how much use the ECB interface would be. As you have most peripherals on-board a bus connection become less important and the connector takes up a lot of space. Also, a lot of board space was taken up with the interfacing chips.

There was an S100 implementation of the V9938 video chip done a while ago:

http://s100computers.com/My%20System%20Pages/VDP%20Video%20B oard/VDP%20Board.htm

Cheers!

Max

Page 2 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by danwerner on Wed, 24 Jan 2018 00:43:06 GMT View Forum Message <> Reply to Message In order to get really good compatibility with MSX game roms, it would be good to avoid keyboard controllers and stick with an 8255 driven switch matrix keyboard. Converting the matrix to a PS/2 was one of the biggest issues with the N8 CBIOS and it is why many (most?) of the games need joystick and do not work with the keyboard.

Dan

Subject: Re: MSX2 Compatible Computer Project Posted by lynchaj on Wed, 24 Jan 2018 01:16:40 GMT View Forum Message <> Reply to Message I think its a great idea. I always liked MSX and there are bits and pieces of MSX scattered in the N8, various ECB boards, and 3 S-100 boards (Z80 CPU, VDP, and Utility). However it never really matured into full blown MSX computer. My advice would be to start from a clean slate and target a full blown MSX computer. You could possibly reuse bits and pieces from the various MSX like board projects but it would probably be just as easy to just do a complete reboot of the idea. Best of luck!

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 24 Jan 2018 01:33:08 GMT View Forum Message <> Reply to Message Thank you for your feedback guys! danwerner wrote on Tue, 23 January 2018 14:55You might take a look a the S-100 archives -- there was some work to put together a MSX system on S-100 cards.

I've looked at them and got inspired But they have a few issues: - Utility board: No MSX2 sub-slots, no memory paging - VDP board: No composite output (RGB is not really useful nowadays) - And as you've mentioned building an S-100 system to play MSX2 games is a bit of an overkill mscane wrote on Tue, 23 January 2018 16:39Hi Sergey,

Maybe an alternative could be to refresh the N8 design with some updates ( https://www.retrobrewcomputers.org/doku.php?id=boards:sbc:n8 :n8

Replace the existing TMS9918 video with a V9938 chip (that would give 80x25 video I believe)Replace the 8255 keyboard interface with an 8242 PS/2 controller (like in the

Page 3 of 148 ---- Generated from RetroBrew Computers Forum VGA3)Change the compact flash interface to a bus connected IDE (in 8 bit mode)Use an ATX style power connector

The N8 also included a floppy interface, SD card and sound chip.

Perhaps you could also consider changing the form factor to match one of the PC standards such as a Mini ITX (17 x 17 mm) or Micro ATX (224 x 224 mm).

I don't feel that N8 approach was a MSX compatible enough. Particularly where it comes to the memory/slots/sub-slots.

What is the reason to use 8242 keyboard controller (other than that PS/2 keyboards are widely available)? It seems that it would make the computer less MSX compatible. I suspect some programs, and especially games, would bypass BIOS and talk to the hardware directly.

Mini ITX / Micro ATX - no real benefit. How to fit MSX cartridge slots, or a bunch of I/O connectors an MSX would have? I can use an ATX power supply connector though...

The the floppy interface and 8-bit CF part makes sense lynchaj wrote on Tue, 23 January 2018 17:16I think its a great idea. I always liked MSX and there are bits and pieces of MSX scattered in the N8, various ECB boards, and 3 S-100 boards (Z80 CPU, VDP, and Utility). However it never really matured into full blown MSX computer. My advice would be to start from a clean slate and target a full blown MSX computer. You could possibly reuse bits and pieces from the various MSX like board projects but it would probably be just as easy to just do a complete reboot of the idea. Best of luck!

That is pretty much my idea.

Subject: Re: MSX2 Compatible Computer Project Posted by lynchaj on Wed, 24 Jan 2018 11:28:29 GMT View Forum Message <> Reply to Message If you can us an integrated Z180 type chip and/or CPLD you probably could reduce the chip count and possibly the PCB space required. Depends on if Z180 type CPUs are MSX compatible though. Don't know if that's the case.

Subject: Re: MSX2 Compatible Computer Project Posted by lynchaj on Sat, 10 Feb 2018 16:43:22 GMT View Forum Message <> Reply to Message Any updates?

Page 4 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Sun, 11 Feb 2018 17:16:31 GMT View Forum Message <> Reply to Message Not much... I have a preliminary schematic and I've started on keyboard PCB layout. Pretty busy at work, so it will take time.

Thanks, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Thu, 22 Feb 2018 17:18:38 GMT View Forum Message <> Reply to Message Hi, I would like to help to help on this project. I had an msx when I was child and I remember few things, I learned them MSX-BASIC and Z-80 Assembler, even I cannot consider myself a software developer.

I was recently working by my part with the same goal. Then I asked some people I fount through internet to share their designs with me (with us), but only one answered to me. This guy developed some hardware, but I had not yet enough time to deep review it. Perhaps he based his design on CPLD more than we would like but for sure we can take advantage from his work. He also mentioned a ps2 keyboard converter. He answered me with this link: http://optotech.net.br/msx/ma_20_neos_kit2+/ Here is his main project page: http://www.optotech.net.br/fzanoto/msx.htm

In addition I was looking for documentation and I think the best book to understand the msx hardware standard is this: (joined text red book). I am still on the second chapter. I don't know if any of you have it. I found that it is actually good to understand the circuit or bios code needed. unfortunately it talks about the first standard (msx1) for the MSX2 standard I have this one, but I don't know if it's so good. (msx2 technical book). One handicap with the schematics after msx1 is their pcb designs use a chip called msx engine (like yamaha S-1985, SMD and actually hard to found) Perhaps we can replace them by a CPLD. As I don't know how easy this could be, I also considered to initiate from the SVI 738 diagram who is almost an MSX2 but doesnt have that special chips (there are many places with upgrading to MSX2 instructions)

Page 5 of 148 ---- Generated from RetroBrew Computers Forum About the keyboard designer web is http://caro.su/msx/kbd4msx/y_yis503.htm (I dont know how good it could work)

I have some more documentation like MSX-DOS documentation (a CPM adapted version for MSX computers).

There is a Spanish guy who got the original source code and upgraded to an S.O. improved version called NEXTOR I don't know if open source or similar. here is his software repository and his blog: http://www.konamiman.com/msx/msx-e.html

I hope this helps. J. Solis

File Attachments 1) TRedbook.zip, downloaded 337 times 2) msxkbd20.jpg, downloaded 433 times 3) MSX2_technical_databook_msxtech2.zip, downloaded 327 times

Subject: Re: MSX2 Compatible Computer Project Posted by traal on Sun, 25 Feb 2018 07:13:04 GMT View Forum Message <> Reply to Message skiselev wrote on Tue, 23 January 2018 17:33- VDP board: No composite output (RGB is not really useful nowadays)

RGBS alone is not so useful, but RGBHV (VGA) monitors are easy to find, even some that support 15kHz signals: 15khz.wikidot.com

I think component video wasn't popular outside the USA, even SCART doesn't support it AFAIK. (Edit: there's a standard pinout for it (green pin=Y, red pin=Pr, blue pin=Pb) but it isn't common.

My vote is for composite (ugh) + RGBS/RGsB/RGBHV/YPrPb over HD15 like what the OSSC supports. Passive cables would then support composite, component, BNC (for professional Sony monitors), SCART, the VGA monitors listed in the link above, and the OSSC for DVI and HDMI. Not S-Video without a converter box but I think that's o.k. with all the other options.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Sun, 25 Feb 2018 09:14:53 GMT View Forum Message <> Reply to Message Hi guys,

Thank you for your feedback!

Page 6 of 148 ---- Generated from RetroBrew Computers Forum jordi.solis wrote on Thu, 22 February 2018 09:18Hi, I would like to help to help on this project. I had an msx when I was child and I remember few things, I learned them MSX-BASIC and Z-80 Assembler, even I cannot consider myself a software developer.

About the keyboard designer web is http://caro.su/msx/kbd4msx/y_yis503.htm (I dont know how good it could work)

I have some more documentation like MSX-DOS documentation (a CPM adapted version for MSX computers).

I hope this helps. J. Solis

Page 7 of 148 ---- Generated from RetroBrew Computers Forum Thanks for this information. MSX (not MSX 2) is fairly straight forward to implement using standard logic. You're right that MSX 2 implementation would be a bit more challenging, since most MSX 2 used an MSX engine IC, and that part I'll need to implement using either standard logic, or maybe using SPLDs. I found the MSX 2 databook with reference schematic, it is in Japanese, but I can read the schematic, and somehow translate the text using an online translator. I'd like to have a native keyboard built using mechanical switches. It will be a header on the motherboard/CPU board connected to the PPI pins used for keyboard interface. And then it will be possible to either connect the mechanical keyboard (with a 4-to-10 decoder and open collector driver ICs on it), or a microcontroller based PS/2 interface. traal wrote on Sat, 24 February 2018 23:13skiselev wrote on Tue, 23 January 2018 17:33- VDP board: No composite output (RGB is not really useful nowadays)

RGBS alone is not so useful, but RGBHV (VGA) monitors are easy to find, even some that support 15kHz signals: 15khz.wikidot.com

I think component video wasn't popular outside the USA, even SCART doesn't support it AFAIK.

That is an interesting perspective. I thought that component video is widespread enough. I have it on all my TVs, and I think I've seen component to SCART converters... but I might be mistaken. So what interfaces are available on the TVs outside of US nowadays? S-Video, SCART?

I can pin out RGBHV and composite... or S-Video and composite... But I really don't want to have 6 different connectors on the rear side of the board, and I also don't particularly like the idea of having headers + breakout cables As an option - I can connect the VDP outputs to a header, and then design one or more daughter boards that would connect to that header and convert VDP output to a usable format.

Subject: Re: MSX2 Compatible Computer Project Posted by traal on Sun, 25 Feb 2018 18:26:14 GMT View Forum Message <> Reply to Message skiselev wrote on Sun, 25 February 2018 01:14I thought that component video is widespread enough... So what interfaces are available on the TVs outside of US nowadays? S-Video, SCART? That's a good question. I've just asked it here. So far it seems composite and SCART were the most common in Europe. skiselev wrote on Sun, 25 February 2018 01:14I can pin out RGBHV and composite... or S-Video and composite... But I really don't want to have 6 different connectors on the rear side of the

Page 8 of 148 ---- Generated from RetroBrew Computers Forum board, and I also don't particularly like the idea of having headers + breakout cables If you had some way to switch between RGBS/RGsB/RGBHV/YPrPb over the HD-15 connector in software or a DIP switch, then you would need only the 1 connector (+composite RCA). But yes, anyone who wants something better than composite would need a compatible VGA monitor or the right cable or converter box. skiselev wrote on Sun, 25 February 2018 01:14As an option - I can connect the VDP outputs to a header, and then design one or more daughter boards that would connect to that header and convert VDP output to a usable format. That works too! You would just need to figure out how to make one case that can fit all the various connector types.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Sun, 25 Feb 2018 20:16:12 GMT View Forum Message <> Reply to Message we have to realize some details that were not listed by the MSX standard. For example, the standard msx1 and msx2 do not mention anything about disk drives, however, while no one msx1 had a floppy disk drive integrated in the case, even no msx2 lacked of it. These details may caused most manufacturers included a chip to integrate a big amount of resources in a new chip the MSX (2) engine. Why they need to reduce the computer board size? they use to sale those computers as keyboard, computer and floppy inside the case, like the apple II or the comodore Amiga 500. J. Solis

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Sun, 25 Mar 2018 23:55:05 GMT View Forum Message <> Reply to Message Hi, As I live in europe I have my own opinion about composite output. First, I think VPD s-100 board has RGB and also composite video output. I used the composite video output on the SCGS card and it's full compatible with SCART with just a BNC to SCART converter. (about 4,00 €). They are few RGB displays here but almost every 21" TV has SCART, VGA and HDMI, what's perfect to connect a pc, a raspberry and soon our msx2.

I hope this helps. J Solis.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Tue, 27 Mar 2018 16:03:23 GMT View Forum Message <> Reply to Message

Page 9 of 148 ---- Generated from RetroBrew Computers Forum Hi all, Are those schematics for an msx2+ useful for our project? I don't know if you saw them before on the internet: https://1drv.ms/f/s!AqjvpN-_7lyIgQjrDhz8OzK0krG8 folders: TPC-310 is a MSX2 and it uses an msx2 engine. Expert2p is an MSX2+ the good news is they don't need any msx2 engine chip, all of them I fount at utsource. let me know Jordi Solís.

Subject: Re: MSX2 Compatible Computer Project Posted by ajacocks on Fri, 13 Apr 2018 01:26:14 GMT View Forum Message <> Reply to Message I think that this sounds like a fascinating project. I'd be very interested to see it move forward.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Wed, 18 Apr 2018 14:53:11 GMT View Forum Message <> Reply to Message I'm interested! I am currently working on a Z80/Z180 based project with a modular setup. I have modules for CPU (Z80 and Z180), serial, V9958, PS2 keyboard/mouse,IDE module and an ROM/RAM module. The idea is to make it MSX compatible. Next step is to change the ROM/RAM module for one which uses a MSX memory mapper and slot mechanism to select slots + ROMs.

Thanks for the Expert2 suggestion! The schematics are better readable than the Sony schematic a was trying to use.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Tue, 01 May 2018 17:18:59 GMT View Forum Message <> Reply to Message Hi, Here you are a link to download some good msx2 software, including an improved version of MSX-DOS 2 called NEXTOR or NBASIC some networking software, and also the whole MSX2 technical handbook in text files. https://github.com/konamiman/msx

Konamiman and Daniel Berdugo also designed software and hardware of an MSX ethernet

Page 10 of 148 ---- Generated from RetroBrew Computers Forum interface witch we can use later ;-) http://obsonet.blogspot.com.es/

I hope this helps.

Jordi Solis

Subject: Re: MSX2 Compatible Computer Project Posted by lynchaj on Wed, 09 May 2018 11:52:26 GMT View Forum Message <> Reply to Message skiselev wrote on Tue, 23 January 2018 16:12Hi,

I'd like to build an MSX2 compatible computer. I'd like to share some of my ideas, and to get opinion of the forum members.

My goals/wishes for this project:

Follow MSX/MSX2 standards as close as possible 128 KiB (or more) RAM Yamaha V9938 VDP, 128 KiB Video RAM, composite and component outputs, with optional RGB output (header) The main purpose would be running MSX/MSX2 games. With CP/M, FUZIX, possibly MSX-DOS support being the secondary goal Two cartridge slots for game cartridges and hardware add-ons (e.g. MSX music, disk controller) Use CBIOS Implement a real keyboard. Likely using Cherry MX keys, and standard keycaps (a microcontroller based PS/2 adapter would be a backup option)

Design modularity and form factor options (which one would you prefer?):

A single board with the entire computer implemented on it. Should be about 200 mm x 160 mm in size. Pros: most compact way, Cons: no modularity at all ECB based system. We already have an MSX (not MSX2) video board, that might somewhat help with developing this project, although a new V9938 based board would have to be implemented. Pros: individual boards can be used for other (non MSX) ECB systems. Cons: more expensive: DIN 41612 connectors, additional bus buffers, etc. Also not as compact Non-ECB backplane based system. Potentially built using 100 mm x 100 mm boards. Pros: cheaper than ECB, no need to adhere to ECB standard, can use some pins for MSX-specific signals (slot select, chip selects). Cons: well, not an ECB Hybrid approach: Main board with CPU, 8255 (slot select, keyboard), I/O decode, sound/joystick, etc. Memory daughter board with SRAM and Flash and memory mapping/paging logic. And a video daughter board. Pros: modular enough, easier debug, a possibility of an upgrade path. For example it include TMS9918, V9938, and perhaps V9958 VDP; or MSX (no paging memory) and MSX2 (paging in slot 3).

Page 11 of 148 ---- Generated from RetroBrew Computers Forum Storage devices:

Floppy disk controller: include on board, or implement as a separate cartridge? Storage: Flash disk (e.g. built using 39SF040), CF, or SD? Perhaps it is possible to implement some kind of flexible cartridge emulation?

Thanks, Sergey

Hi Thinking more about this project. Any updates? I agree with the project goals and it should target 100% MSX2 compliance. Past projects always fell short and doomed them.

Regarding modularity, I like the hybrid approach. How to implement? ECB & S-100 is overkill. Making stackable PCBs (PC104) is difficult and parts expensive. Also the boards need to be big enough to provide enough room for components without extreme routing. I suggest a double wide euro board 160mmx200mm with holes in corners to mount. Then use right angle dip dual row headers and modified IDE cables as a bus. Maybe 2 or 3 bus connectors per board. segregate the design into boards like (CPU + memory + 8255 + IO decode), (video, keyboard & mouse (MCU PS/2), sound), (IDE, SD, floppy drive) keyboard should be switched matrix just like MSX design with header to separate keyboard PCB. I suggest cpu is Z180 class to reduce part count.

The idea is to separate CPU from IO functions so boards could be upgraded without scrapping whole stack but not be constrained like ECB and/or S-100. In theory a common IO stack could be used for non-MSX compatible CPU boards like 65xx, 68xx, 68030, etc. Something like C-128 switching between 6510 and Z80 processors.

Subject: Re: MSX2 Compatible Computer Project Posted by lynchaj on Wed, 09 May 2018 13:49:18 GMT View Forum Message <> Reply to Message Hi another thing a modern MSX computer should have is Ethernet. There are some 8 bit Ethernet chips which I think would be compatible with Z80/Z180 type computer. Also 8 bit USB. I realize MSX standard did not include Ethernet or USB but are vital to modern computer connectivity.

Page 12 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Wed, 09 May 2018 14:16:34 GMT View Forum Message <> Reply to Message Dear, I think the Standard is on expansion. they have some Ethernet in the market and others. I attach you a link for a Spanish manufacturer web page. He has Ethernet, PS/2 keyboard, four slot backplanes and more. Look at this: http://msx.deneb.nl/index.html

This is a expanded MSX (he say 100% ANSI compatible), perhaps you like this modular schema.

In my past posts I included a link to Nextor. Nextor is an Operative System based on source code of ANSI MSX-DOS. So is an upgrade, if we go to a 100% standard we must think on use its software, rom bios, etc) I think remember one of it's upgrades is ethernet driver support.

What if we start copying an MSX2 design that we know is working and then we add modularity on the design. J. Solis.

Subject: Re: MSX2 Compatible Computer Project Posted by lynchaj on Thu, 10 May 2018 12:12:19 GMT View Forum Message <> Reply to Message Hi Of the MSX schematics I've looked at the SpectraVideo 738 (SVI 738) seemed to be the best. It is MSX (not MSX2) but I think it would make a good starting point. Even as a clone initially and once shown to work add more capability, full MSX2 compliance, etc. another thing is the cartridge port should be on a dual row pin header not an edge connector directly connected to the main planar. The cartridge port needs to be securely mounted and insertion/removal of cartridges put a lot of strain on the PCB planar leading to failures. Along those lines, I suggest all the IO connectors should be dual row pin headers and connected by ribbon cables to the physical connector. It saves a lot of PCB space and decouples the PCB from the connecting cable. I think it is much more robust and reliable design.

One thing I'd like to see but have never gotten it work myself is a "community project site" with open access, configuration controlled schematics, software, etc. allowing multiple people to work on it at once.

Sergey: are you still interested in this project or has it gone dormant?

Page 13 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Thu, 10 May 2018 18:03:57 GMT View Forum Message <> Reply to Message lynchaj wrote on Thu, 10 May 2018 05:12Hi Of the MSX schematics I've looked at the SpectraVideo 738 (SVI 738) seemed to be the best. It is MSX (not MSX2) but I think it would make a good starting point. Even as a clone initially and once shown to work add more capability, full MSX2 compliance, etc. another thing is the cartridge port should be on a dual row pin header not an edge connector directly connected to the main planar. The cartridge port needs to be securely mounted and insertion/removal of cartridges put a lot of strain on the PCB planar leading to failures. Along those lines, I suggest all the IO connectors should be dual row pin headers and connected by ribbon cables to the physical connector. It saves a lot of PCB space and decouples the PCB from the connecting cable. I think it is much more robust and reliable design.

Sergey: are you still interested in this project or has it gone dormant?

It seems the SVI 738 contains 2 ULA's, so not so usable as an example to build on. Or did you mean SVI 728?

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Thu, 10 May 2018 18:42:33 GMT View Forum Message <> Reply to Message Andrew,

I am still interested in the project. But I am currently very busy with work and life (almost summer! so camping/hiking/climbing . So probably the actual work will have to wait until later this year (September and on).

I do like some of the ideas above. I am not comfortable with using CPLDs/FPGAs. Using SPLDs might be OK.

I assume that various extensions, like Ethernet, USB and Flash/disk can be implemented as slots?

What are the advantages of using Z180? I don't think that Z80 design is too complicated. There is some I/O and memory decode logic, but other than that Z80 is very simple to interface with. Probably no advantage of higher CPU speed/clock either. Most of MSX/MSX2 software is designed to work with 3.58 MHz frequency anyway.

Thanks,

Page 14 of 148 ---- Generated from RetroBrew Computers Forum Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Fri, 11 May 2018 08:44:04 GMT View Forum Message <> Reply to Message I am busy completing an add in cart for my current modular Z80/Z180 retro build. It should provide a MSX memory mapper (1MB), MSX slot/subslot mechanism, pageable FlashROM and 1 MSX catridge slot. If it works I'll extend the design to include the CPU and make it into a SBC with slots for video and regular MSX slots.

Subject: Re: MSX2 Compatible Computer Project Posted by lynchaj on Fri, 11 May 2018 12:36:54 GMT View Forum Message <> Reply to Message skiselev wrote on Thu, 10 May 2018 14:42Andrew,

I am still interested in the project. But I am currently very busy with work and life (almost summer! so camping/hiking/climbing :)). So probably the actual work will have to wait until later this year (September and on).

I do like some of the ideas above. I am not comfortable with using CPLDs/FPGAs. Using SPLDs might be OK.

I assume that various extensions, like Ethernet, USB and Flash/disk can be implemented as slots?

Thanks, Sergey Hi Sergey, OK. Enjoy your summer Agree on the CPLD/FPGAs. On the Gryphon project we tried to consolidate some of the glue logic into a CPLD with mixed results. Based on that experience I would stick to 74xx type logic and maybe some common DIP GALs where they really work well. Trying to stuff too much into CPLDs and FPGAs just changes the problems without actually making things better. Also Gryphon (and N8) attempted to consolidate all the IO on one board and it just didn't work too well. I think it needs a better balance between consolidation and modularity.

I think the main advantage of the Z180 CPU is it has higher integration and can lead to lower chip

Page 15 of 148 ---- Generated from RetroBrew Computers Forum count. Also it is capable of higher clock speed but would need to be clock selectable for compatibility sake. The N8 board used a Z180 and it worked well. I am not stuck on this point but it is an opportunity to simplify the design.

What I'd really like to see is a hybrid modular design which separates common IO into a couple of boards. One board for common storage functions (IDE, SD, Ethernet, USB, floppy, etc.) and another for user interface (video, audio, keyboard & mouse, joysticks, switches, etc.). Keep the processor & memory specific functions on a separate board with a standardized interface to the IO boards. S-100 has enough room but too complicated. ECB has a good interface but the PCBs are too small. A common IO stack could be reused across multiple projects not just Z80 MSX although that is a good starting point.

I think a cartridge slot is good but is mostly useful for EPROM cards and unusual/specialized devices. I would keep the common IO on the two IO boards and reserve the cartridges for games, applications, user customization, etc.

I think we can make something which increases PCB size and has a simpler less expensive expansion bus. For consideration, I think the 40 conductor ribbon cable (IDE) would work well. One 40 pin dual row header replicates the Z80 bus (as is) and another to carry the MSX unique chip selects & other miscellaneous signals. Power & ground may need a separate low impedance connection. Plus no need for a separate backplane PCB.

Glad to see the project is still alive.

Subject: Re: MSX2 Compatible Computer Project Posted by lynchaj on Fri, 11 May 2018 12:42:13 GMT View Forum Message <> Reply to Message lintweaker wrote on Thu, 10 May 2018 14:03 It seems the SVI 738 contains 2 ULA's, so not so usable as an example to build on. Or did you mean SVI 728?

Hi Probably so. I recall the one used 74xx type logic not custom logic chips. It has been a while so my memory has faded. I recall studying it while working on the S-100 Z80 CPU board, S-100 VDP, and S-100 Utility board. The theory was to make an MSX like system for S-100 which had mixed success. However for this project those boards would serve as rich sources for component libraries and part footprints in KiCAD

Subject: Re: MSX2 Compatible Computer Project Posted by lynchaj on Fri, 11 May 2018 12:54:36 GMT View Forum Message <> Reply to Message lintweaker wrote on Fri, 11 May 2018 04:44I am busy completing an add in cart for my current

Page 16 of 148 ---- Generated from RetroBrew Computers Forum modular Z80/Z180 retro build. It should provide a MSX memory mapper (1MB), MSX slot/subslot mechanism, pageable FlashROM and 1 MSX catridge slot. If it works I'll extend the design to include the CPU and make it into a SBC with slots for video and regular MSX slots.

Hi Is your design posted anywhere so I can see it? How far along is it?

Subject: Re: MSX2 Compatible Computer Project Posted by lynchaj on Sat, 12 May 2018 16:27:42 GMT View Forum Message <> Reply to Message Hi My memory of the schematic was wrong. I think I used the Goldstar FC-200 as inspiration on the S-100 Utility.

Looking over the design it might make more sense to just implement the whole thing on a single planar PCB and use the cartridge port for expansion.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Sat, 12 May 2018 18:37:26 GMT View Forum Message <> Reply to Message Hi Andrew, Do you think is a wrong idea to use those schematics from another hobbyist? they are MSX2 and MSX2+, I think. https://1drv.ms/f/s!AqjvpN-_7lyIgQjrDhz8OzK0krG8

I think I have the eagle design too. let me know.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Sun, 13 May 2018 06:59:44 GMT View Forum Message <> Reply to Message The Goldstar FC-200 service manual has nice detailed descriptions. Some parts are certainly usable as the form the basics of an MSX computer. Odd thing about the Goldstar, it mentions having Video Out on pin 16 of the catridge slot. That is non-standard. Normally pin 16 is a No Connect.

The Expert2 and 3 are very clear schematics to base an MSX2(+) on. Does anyone know if these schematics have ever been build? I used the Expert2 schematic to base my memory mapper / slot /subslot mechanism on, hopefully

Page 17 of 148 ---- Generated from RetroBrew Computers Forum there are no bugs in the schematic.

Subject: Re: MSX2 Compatible Computer Project Posted by lynchaj on Mon, 14 May 2018 11:59:06 GMT View Forum Message <> Reply to Message jordi.solis wrote on Sat, 12 May 2018 14:37Hi Andrew, Do you think is a wrong idea to use those schematics from another hobbyist? they are MSX2 and MSX2+, I think. https://1drv.ms/f/s!AqjvpN-_7lyIgQjrDhz8OzK0krG8

I think I have the eagle design too. let me know.

Hi Can't access your files. Would you repost as a ZIP file attached to a message on forum?

Subject: Re: MSX2 Compatible Computer Project Posted by pbirkel on Mon, 14 May 2018 12:33:28 GMT View Forum Message <> Reply to Message All three folders in a single ZIP, attached. File Attachments 1) RETROBREW.zip, downloaded 495 times

Subject: Re: MSX2 Compatible Computer Project Posted by lynchaj on Tue, 15 May 2018 12:42:28 GMT View Forum Message <> Reply to Message Thanks for posting the ZIP file.

I think I am going to wait until Sergey gets back and then follow his lead on this. It will be interesting where this project goes.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Tue, 15 May 2018 15:35:25 GMT View Forum Message <> Reply to Message My "MSX mapper / slot mechnism / BIOS ROM / MSX cartridge slot" PCB is now being made in China. I used SMD for all 74-series chips, never done that before. Let's see how it turns out.

Page 18 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by lynchaj on Wed, 16 May 2018 13:47:13 GMT View Forum Message <> Reply to Message Hi Would you post your design here in the forum. It would help see what you are developing.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Thu, 17 May 2018 09:57:47 GMT View Forum Message <> Reply to Message Hi,

As soon as my setup has enough of the MSX hw and can run C-BIOS I can start thinking about creating on github and sharing it. So hopefully in the coming months.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Wed, 13 Jun 2018 16:18:10 GMT View Forum Message <> Reply to Message So I got my MSX mapper / slot mechnism / BIOS ROM / MSX cartridge slot" PCB and soldered all the components. Unfortunately there are some issues I tried to debug but so far could not fix. What works: - slot/subslot mechanism through the PPI - booting from Flash ROM - 1Mbit Flash ROM mapped in 32k blocks to slot 0-0, 0-1, 0-2 and 0-3 - Memory mapper (not fully tested), see below

What does not work / has issues: - Memory, seemingly due to timing issue. - Somehow IO port reads has issues while write IO ports works just fine (V9958 video works)

I am now preparing a new revision of the PCB with much more test points and mostly DIP chips only. If there is interested I can post the current schematic for some feedback.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Sat, 30 Jun 2018 19:29:06 GMT View Forum Message <> Reply to Message New SBC style boards are in, managed to get MSX1 working! Even starts a game from a slot 0 subslot in the same flash. The board has some issues so a respin is needed. First build a PS/2 to parallel keyboard converter.

Page 19 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by rhkoolstar on Sat, 30 Jun 2018 20:16:58 GMT View Forum Message <> Reply to Message You can probably build a kb interface using an AVR and 'borrowing' code from Grants 'simple video and keyboard interface' here: http://searle.hostei.com/grant/#SimpleVideo

Rienk

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Sun, 01 Jul 2018 08:02:52 GMT View Forum Message <> Reply to Message Thanks, yes something like that is the plan. I have some test PS/2 code running,using a generic PS/2 lib, on a Mega 2560. PS/2 key presses appear a bit slow. I'll check if Grant's version.

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Mon, 02 Jul 2018 02:46:53 GMT View Forum Message <> Reply to Message linkweaker,

Grant's interface works pretty well. But I think his code might be based around Ben Ryves', and the video controller is based on Daryl Rictor's work. But, it may be something you can modify, I think he provides the source.

Out of curiosity, do you have picture of the current version of the board? I'm sure we'd all love to see it.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Mon, 02 Jul 2018 14:56:08 GMT View Forum Message <> Reply to Message Here is a picture of my current setup: https:// github.com/lintweaker/z8ty/blob/master/z8ty-sbc-rev1-dbg.jpg Z8TY SBC Rev 1 with Z80,8255,1Mbit Flash, 2Megs of SRAM, MSX memory mapper, MSX slot mechanism. Inserted in the SBC is the videocard with V9958 and 128Kbytes of VRAM.

Page 20 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Mon, 02 Jul 2018 14:58:39 GMT View Forum Message <> Reply to Message jdgabbard wrote on Sun, 01 July 2018 19:46linkweaker,

Out of curiosity, do you have picture of the current version of the board? I'm sure we'd all love to see it. The C-code seems to need/use AVR Studio, I am not familiar with it. For now I'll stick with Arduino. Maybe I'll try it later on in the project.

Picture in my previous post

Subject: Re: MSX2 Compatible Computer Project Posted by Andrew B on Mon, 02 Jul 2018 19:03:54 GMT View Forum Message <> Reply to Message You could also implement a Parallax Propeller based PS/2 to ASCII controller pretty easily. The PropIO ECB board uses this, as does John Monahan's S-100 Propeller Console board. These have been tested/used for years now. Removing the video portion would make for a very simple circuit.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Tue, 03 Jul 2018 16:09:26 GMT View Forum Message <> Reply to Message Hi folks, I think you need parallel communication with the 8255 chips for full compatibility with all the msx software. So even if we use a propeller I think the software should be rewritten. Did you look for this?

I hope my link helps you. http://www.optotech.net.br/msx/teclado_ps2/avr/msxkbd20.jpg

Jordi Solis.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Tue, 03 Jul 2018 17:15:46 GMT View Forum Message <> Reply to Message

Page 21 of 148 ---- Generated from RetroBrew Computers Forum Hi, Thanks for the link. My board provides the needed signals for a parallel keyboard (8 + 4). So for my design the AVR or similar controller needs at least 12 I/O pins available, next to the pins needed for PS/2.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Tue, 03 Jul 2018 17:17:18 GMT View Forum Message <> Reply to Message As a quick update. I managed to make some headway with MSX2 support. It now shows the MSX2 bootlogo (with green foreground colour due to missing RTC) but does not go to BASIC.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Wed, 04 Jul 2018 17:16:10 GMT View Forum Message <> Reply to Message If anyone has any examples for audio opamp circuits with line level output for the PSG (YM2419). I am busy with the MSX PSG/Joystick part but the audio amplication bit is totally out of my realm of expertise. I'd prefer to use only a single power supply (so no negative 12v/5v).

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Sat, 07 Jul 2018 11:06:51 GMT View Forum Message <> Reply to Message Small update: managed to get MSX2 BIOS and I am now struggling to get the keyboard running ... so far no luck...

Subject: Re: MSX2 Compatible Computer Project Posted by b1ackmai1er on Sat, 07 Jul 2018 11:50:13 GMT View Forum Message <> Reply to Message lintweaker wrote on Wed, 04 July 2018 10:16If anyone has any examples for audio opamp circuits with line level output for the PSG (YM2419).

Maybe compatible audio output?

https://www.986-studio.com/2015/05/07/update-on-ay-3-8910-sc hematic/ https://github.com/electrified/rc2014-ym2149

Page 22 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Sun, 08 Jul 2018 13:56:21 GMT View Forum Message <> Reply to Message b1ackmai1er wrote on Sat, 07 July 2018 04:50lintweaker wrote on Wed, 04 July 2018 10:16If anyone has any examples for audio opamp circuits with line level output for the PSG (YM2419).

Maybe compatible audio output?

https://www.986-studio.com/2015/05/07/update-on-ay-3-8910-sc hematic/ https://github.com/electrified/rc2014-ym2149

Thanks, it looks like most AY-3-8910/YM2149 schematics I've seen do not use amplication. I'll build a version on a breadboard first to test with.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Sat, 14 Jul 2018 16:09:29 GMT View Forum Message <> Reply to Message Progress update: keyboard now mostly working (PS/2 to MSX parallel keyboard). I have issues with a few SHIFT versions of keys e.g. '1' not giving '!' with SHIFT held. It's starting to get to a workable MSX2.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Thu, 23 Aug 2018 18:24:07 GMT View Forum Message <> Reply to Message As it seems I am the only one left posting here, I final update. After fixing a silly issue in one of my PLDs the memory mapper and cartridge slots are working like a charm. The full 1Mbyte can be accessed and the system is now a fully working MSX2+.

Subject: Re: MSX2 Compatible Computer Project Posted by ajacocks on Thu, 23 Aug 2018 18:26:15 GMT View Forum Message <> Reply to Message You're definitely not the only one interested, though.

I'd love to build a clone of your board.

- Alex

Page 23 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by b1ackmai1er on Fri, 24 Aug 2018 07:38:23 GMT View Forum Message <> Reply to Message Yes keep the updates coming. I don't have the skills to contribute but am facinated by the opportunity to build a system with a commercial software base.

As much fun as CP/M is, I'm not likely to complete the Zork Trilogy

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Fri, 24 Aug 2018 08:28:44 GMT View Forum Message <> Reply to Message Good to see some interested people I'll keep posting whenever there is an update.

TODO's: - respin current SBC board: add missing /M1 wait circuit (currently added via breadboard). Needed to avoid screen corruption and full MSX compatibility add missing pullup on data bus so reading unused IO ports gives 0ffh back (currently added via breadboard) find a (fully) working solution for PS/2->parallel MSX keyboard converter. Current version (mostly) works okay in BASIC and MSXDOS(2) but has trouble in games [option] add 2 extra sockets for SRAM for max 2Mbyte support

- add 'bottom' board with (in v1): Ricoh RP5-C01 (RTC) YM2149 SSG/PSG with joystick ports and audio out 0f4h IO port, bit 7 (MSX2+ do not show logo on softboot) video circuitry (V9958) - probably on v2

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Fri, 24 Aug 2018 13:19:42 GMT View Forum Message <> Reply to Message Hi lintweaker, I'm interested too. I'm not sure if I have enough skills but let me know any way I can help you or just suggest your needs. Jordi Solis.

Subject: Re: MSX2 Compatible Computer Project

Page 24 of 148 ---- Generated from RetroBrew Computers Forum Posted by lintweaker on Fri, 24 Aug 2018 18:59:26 GMT View Forum Message <> Reply to Message Thanks for the support. I am currently trying to get a,solid fully working, keyboard controller solution. Current direction is asserting /WAIT when the MSX is setting the keyboard row to scan. This will hopefully give the AVR uC the needed time to respond.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Sat, 06 Oct 2018 13:53:41 GMT View Forum Message <> Reply to Message at last a new update. Just sent rev 2 of my design to jlpcb. This time a 4 layer job (my first 4-layer board). Changes/additions from my rev1: - support for 4Mbit flash, via dip switches selectable in 4x 1Mbit for MSX1/MSX2/MSX2+/other boot option - extended memory mapper to 2Mbyte (was 1Mbyte) - added 1284p AVR for PS2->MSX keyboard conversion - added F4 IO port (MSX2+) for soft reboot option - added Ricoh RP5C01 RTC - added pullups on data lines - added /M1 WAIT circuit - extra /WAIT signal for keyboard controller - +12V en -12V power supply for future sound support - cartridge slots with the correct spacing

I am also working on a Z280 CPU module based on plasmo's ZZ80RC

Subject: Re: MSX2 Compatible Computer Project Posted by ajacocks on Sat, 06 Oct 2018 17:22:36 GMT View Forum Message <> Reply to Message Very cool. I'd love to build one of these, as soon as you stabilize the design.

Great work! - Alex

Subject: Re: MSX2 Compatible Computer Project Posted by etchedpixels on Thu, 11 Oct 2018 12:29:20 GMT View Forum Message <> Reply to Message

Page 25 of 148 ---- Generated from RetroBrew Computers Forum nice - you found a solution to the keyboard problem then ?

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Fri, 12 Oct 2018 06:10:55 GMT View Forum Message <> Reply to Message The keyboard solution is not yet 100% but very usable. I am open for suggestions

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Sat, 20 Oct 2018 10:09:19 GMT View Forum Message <> Reply to Message Rev 2 of my board is alive! Still waiting for some parts to show up to complete the build (clockchip, some caps). I also made a Z280 board but I am having issues with it. It seems to get hot quite fast and sometimes it causes issues with the powersupply.

New Rev 2 board:

The top cartridge slot is not usable due to space issues so a least one new board revision is needed...

Z280 module:

Subject: Re: MSX2 Compatible Computer Project Posted by plasmo on Sat, 20 Oct 2018 13:15:57 GMT View Forum Message <> Reply to Message Z280 shouldn't get hot even after long operation. It may feel warm to the touch. A basic Z280 board with low-power RAM and HC TTL logic draws around 150mA@5V with 24MHz clock. Bill

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Sat, 20 Oct 2018 14:55:40 GMT View Forum Message <> Reply to Message plasmo wrote on Sat, 20 October 2018 06:15Z280 shouldn't get hot even after long operation. It may feel warm to the touch. A basic Z280 board with low-power RAM and HC TTL logic draws around 150mA@5V with 24MHz clock.

Page 26 of 148 ---- Generated from RetroBrew Computers Forum Bill Thanks, I figured as much. I have attached the schematic. Can you check to see if I did not make any silly errors? (there is at least one: X2 nc pin connected to GND :/ File Attachments 1) z280.pdf, downloaded 222 times

Subject: Re: MSX2 Compatible Computer Project Posted by plasmo on Sun, 21 Oct 2018 01:03:10 GMT View Forum Message <> Reply to Message A few questions regarding the schematic: * There should be four ground pins: 1, 35,51,53. Your schematic only show two (1,53). * Z280 VCC & GND pins are not connected on the schematic. I assume they are in fact connected? * Z280 CLK is not connected. It is a fairly important signal that serves as the reference for timing such as nWAIT generation. Bill

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Sun, 21 Oct 2018 06:41:30 GMT View Forum Message <> Reply to Message plasmo wrote on Sat, 20 October 2018 18:03A few questions regarding the schematic: * There should be four ground pins: 1, 35,51,53. Your schematic only show two (1,53). * Z280 VCC & GND pins are not connected on the schematic. I assume they are in fact connected? * Z280 CLK is not connected. It is a fairly important signal that serves as the reference for timing such as nWAIT generation. Bill

Thanks for looking into it. You are onto something wrt those ground pins! Pin 35 and 51 are currently not connected, fixing that will hopefully resolve 'the heating problem' All other VCC and GND pins are connected to VCC/+5V and GND respectively, not very clear in the schematic.

I am not using the Z280 CLK output as the rest of the board runs on the CLK (3.58MHz) coming from the VDP (V9958). Maybe in a next revision I'll make the Z280 CLK signal usable with a 7474. Thanks!

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Mon, 22 Oct 2018 14:41:48 GMT View Forum Message <> Reply to Message

Page 27 of 148 ---- Generated from RetroBrew Computers Forum Small update: after properly connecting all GND pins the Z280 no longer runs hot. Thanks again Bill! The MPU started to show some healthy signals but does not boot my current ROMs. Waiting for a breakout board to connect my LA to.

Subject: Re: MSX2 Compatible Computer Project Posted by plasmo on Mon, 22 Oct 2018 16:09:36 GMT View Forum Message <> Reply to Message Have you tried UART bootstrap? If you can change the RAM address map to 0x0 or wire a RAM to the 2x22 connector, you should be able to load a small file loader via the serial port and bootstrap up. I have a small fileloader if you want to try that. Bill

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Mon, 22 Oct 2018 16:26:40 GMT View Forum Message <> Reply to Message plasmo wrote on Mon, 22 October 2018 09:09Have you tried UART bootstrap? If you can change the RAM address map to 0x0 or wire a RAM to the 2x22 connector, you should be able to load a small file loader via the serial port and bootstrap up. I have a small fileloader if you want to try that. Bill Have not tried UART bootstrap yet, I am not sure if the bootstrap settings even work. Once I can (more easily) hookup my LA I can verify if the Z280 is executing code or not.

BTW does the Z280 send out data when doing a UART boot?

Subject: Re: MSX2 Compatible Computer Project Posted by plasmo on Mon, 22 Oct 2018 17:55:26 GMT View Forum Message <> Reply to Message During UART bootstrap Z280 is offline and the UART is strictly in receive mode, whatever it received over the serial port is written to RAM starting from 0x0 to 0xFF. When the 256th bytes is received, Z280 wakes up and start execution from location 0x0, just like a regular reset. What Z280 does is up to the 256-byte program. My program, TinyLoad, clears memory, signs on with a message, and waits for Intel Hex load file or a 'go' command. It is an easy way to explore Z280 because you are starting from the reset condition with clear set of memory. Bill

Subject: Re: MSX2 Compatible Computer Project

Page 28 of 148 ---- Generated from RetroBrew Computers Forum Posted by lintweaker on Thu, 25 Oct 2018 16:23:56 GMT View Forum Message <> Reply to Message Yeeeh, managed to get MSX1 booting with the Z280! It currently takes some fiddling to get the Z280 running. Needs some more investigation. MSX1 speed looks quite fast. My current PS2->MSX keyboard solution cannot keep up...more work...

MSX2+ does currently not boot on the Z280...needs more investigation as well...

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 29 Oct 2018 17:34:14 GMT View Forum Message <> Reply to Message The summer fun is mostly over here in Oregon, and now I have a bit more time to work on the projects. It looks that Jurgen made quite a progress on his MSX compatible project. I am quite excited to see it. Meanwhile I spent some time working on MSX keyboard. The keyboard uses Cherry MX switches, and standard MX keycaps. The board layout assumes that the keyboard will be mounted on the top of the main board, and to that either using a ribbon cable or a socket / header mounted directly to the PCB The Caps and optional Kana LEDs are integrated into respective keys. The schematic and the board layout are attached. I'd appreciate your feedback.

File Attachments 1) Omega-Keyboard-Schematic-0.8.pdf, downloaded 215 times 2) Omega-Keyboard-Board-0.8.pdf, downloaded 216 times

Subject: Re: MSX2 Compatible Computer Project Posted by etchedpixels on Mon, 29 Oct 2018 17:52:03 GMT View Forum Message <> Reply to Message While I am not interested in it for MSX a decent matrix keyboard for retro projects would be wonderful. I would certainly want to build one and hook it to a Z80 PIO for my RC2014 systems. Whilst there is a 40 key keyboard design for the RC2014 it's a bit too toy computer for me.

Alan

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Mon, 29 Oct 2018 18:56:51 GMT View Forum Message <> Reply to Message

Page 29 of 148 ---- Generated from RetroBrew Computers Forum @Sergey, nice keyboard! My current solution does not cut it when using a Z280. It is just not fast enough. Your keyboard would be a great option.

Small update as well, got the Ricoh RP5C01 RTC chips and got it working today. Small error on the PCB but it was fixable with a little wire.

WRT my Z280 upgrade board, with some test code I found out it is not picking up the bootstrap settings at startup. Too bad, now I cannot test with 4x speed...

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 29 Oct 2018 22:04:59 GMT View Forum Message <> Reply to Message @lintweaker: You've made a great progress, so I don't really see a need to do my own MSX2 design. Yet, depending on your design choices, I might need to change the layout a bit. Ideally, I'd like to have a system with a typical 80's MSX2 form factor - a single unit with a built-in keyboard. And so I'll need to match the main board and keyboard dimensions, and the mounting holes of the main board and the keyboard. If needed, I can modify the keyboard PCB layout. Or, if you're interested, I can post the KiCad files for the keyboard, and you can either suggest the changes to the keyboard layout, or modify the main board accordingly.

Now, I have a few questions and comments (my own opinion on the questions) regarding your project:

1. Most importantly - do you plan to release the project as an open source? Any plans to make the schematic and the PCB design available? I am interested in reviewing the schematic, and if needed modifying the PCB layout as I stated above.

2. What form factor do you envision for your project? Is it a stand-alone case with a separate keyboard, late 70-s/80-s home computer style - a single unit with a built-in keyboard, or something else?

3. Do you plan to integrate the V9938 or V9958 MSX Video on the main board, or keep it as a separate board? Both approaches have their advantages. The integrated video might be cheaper (less PCBs), and more compact. The separate card is more upgradeable - for example it might be a choice between TMS9918, V9938, or V9958, and perhaps that would be easier to troubleshoot. In case of a separate card, it might be preferable to mount it parallel to the main board - either on top or on the left size of the board.

4. Do you plan to keep the Z280 as an upgrade board, or integrate it in the main board? I personally like the upgrade option better. While it is an interesting upgrade, yet very little original MSX2/MSX2+ software would benefit from it, as it was designed for Z80 running at 3.58 MHz. Again, in case of an upgrade board, it would be nice to mount it parallel to the main board.

5. I don't see the PSG yet, although you've mentioned it in an earlier comment. Is it still in works?

Page 30 of 148 ---- Generated from RetroBrew Computers Forum 6. Do you have any plans for an integrated floppy disk controller? A WD37C65C based controller would be very straight forward to implement - only a single IC and a connector, assuming that you have an available chip select output and and some Flash ROM space.

7. Any particular reason for using the Z80 CPU and the 8255 in PLCC packages? Historically DIP-40 package seems to be more common and somewhat easier to work with. Although I can understand that for the brand new components it might be easier to purchase PLCC parts.

8. Do you plan to implement the MSX printer port and the cassette port? I am not sure if there is any interest in these ports, but when they are not that difficult to implement. So if the PCB space allows, I'd rather have them.

Thanks, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Sat, 03 Nov 2018 07:38:48 GMT View Forum Message <> Reply to Message @Sergey, To answer your questions. 1. Yes, as soon as development is stabilized I can share the KiCAD files. Currently the schematic is a bit a of mess, everything in one very big sheet (a combination of many previous seperate boards). I can release the schematic sooner if needed 2. Not really thought of any permanent housing. It is still work in progress 3. My plan is to build a top or bottom board (depending on size needed) for the video and audio part. A simple next step could be to lay the current video board flat and make a simple board with the appropriate connector I am sticking with a V9958 as I have a few of those and are backwards compatible (software) with V9938 en TMS9918/28. 4. Z280 is just a side project in an attempt to see if it's possible to get Turbo-R like performance. I looking promising but there are some (odd) issues which need to be resolved to make it really workable. The speed is nice for MSX-DOS(2) and assembling / editing etc. Ideally Z280 and Z80 should be switchable while running or at least at cold boot. 5. PSG + joystick port are next on my agenda. Hardest part (for me) is to get/figure out a proper amplification solution combining sound from PSG, key click and the cartridge connectors and future OPL chip Maybe I'll start with a 'simple' addon cart with PSG + Joystick ports and headers for audio 6. Yes, I would be nice to have a real floppy controller on board (although I do have a number of original MSX external floppy drives and current SD/uSD/CF solutions). When I am going to build it, the 3765 will be my first choice 7. I started out with a DIP40 Z80 but wanted to try PLCC. After a successful try with the Z80 in PLCC44 I also got a few 8255's in PLCC44. I'll stick with PLCC's. 8. A MSX printer port is not on the list, although easy to implement I do not have any use for it. A cassette port could be nice to play with cassette emulation but as mentioned I do have plenty modern disk options

Page 31 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Fri, 09 Nov 2018 15:53:47 GMT View Forum Message <> Reply to Message I have uploaded the schematics for my current Rev 2 board to my github page. https://github.com/lintweaker/z8ty The current version is a combination of lots of separate boards I created/build earlier put together in one big schematic (so a bit messy). Comments, questions and suggestions are welcome!

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Thu, 29 Nov 2018 01:56:01 GMT View Forum Message <> Reply to Message Attached is the schematic for my variant of MSX2 compatible system. It is based on lintweaker's work, on MSX datapack specs, as well as on multiple other sources.

A few notes:

- I plan to use a CPU supervisor circuit - ADM693/MAX693. This IC would generate proper reset signals and provide the battery power and chip select signals to the RTC (replacing a few transistors and several passive components)

- I tried to implement a flexible slot selection: * The extended slot can be set to either slot 0 or slot 3 * The RAM can be either set to slot 3 or sub slot 2 (so it will be either slot 3, slot 0-2, or slot 3-2). * The ROM is divided into four 64 KiB chunks, each one can be mapped to a different slot or sub slot. The intention is that the first chunk will be used for the Main MSX ROM, and the second for the Sub ROM, while 2 more are available for future extensions (e.g. Disk ROM). Now, I didn't do anything to prevent any part of the 64 KiB chunk to be mapped to the CPU. For example the 0x8000-0xFFFF area of the 64 KiB chunk containing Main ROM can be mapped, although it is not normally used by MSX. My assumption is that MSX BIOS and applications will not do that (and even if they do, it shouldn't be any harm... but please correct me if I am wrong).

- The default VDP for the system is v9938, but I've added a jumper that should make v9958 work as well. The video output is connected to an AD724 NTSC/PAL encoder with Composite and S-Video outputs. The encoder is set for NTSC timing (modern TVs are multi-system anyway, unless you're in US where they are NTSC). The RGB+Sync signals are available on the headers in case a different video output is desired. In my own opinion S-Video should provide a good enough quality, and if needed there are inexpensive S-Video to HDMI converters available. I'd appreciate though if someone will review the video output part of the schematic.

- I used a single supply op amp for the low pass filter for the PSG. Again, I'd appreciate if someone with analog electronics knowledge would check that part of the schematic

Thanks, Sergey

Page 32 of 148 ---- Generated from RetroBrew Computers Forum File Attachments 1) Omega-Mainboard-Schematic-0.4.pdf, downloaded 407 times

Subject: Re: MSX2 Compatible Computer Project Posted by ajacocks on Fri, 30 Nov 2018 16:17:06 GMT View Forum Message <> Reply to Message Looks great, as always, Sergei!

I'd love to build one, when it gets that far.

- Alex

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Fri, 30 Nov 2018 16:57:55 GMT View Forum Message <> Reply to Message Yes, nice schematic Sergey!

I am waiting for my 'Duo Sound' boards to arrive (YM2149 and YM2413) so I can finally have sound (and joystick ports). Today I finished my floppy board (WD37C65), it starting to get fairly complete.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Sun, 02 Dec 2018 15:23:05 GMT View Forum Message <> Reply to Message Made some good progress today. 'Duo Sound' board is up and running! Both joystick and sound work but the sound is distorted, probably due to over-amplification. Hopefully fixable by changing some resistor values. Floppy board is already on its way...

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Tue, 11 Dec 2018 19:06:31 GMT View Forum Message <> Reply to Message Meanwhile, I did some updates to my schematic. I've replaced multiple discrete logic ICs in slot select logic, slot data bus direction logic, and wait logic with a couple of SPLDs. Hopefully shouldn't be much problem, since the system already uses an SPLD for I/O address decode.

Page 33 of 148 ---- Generated from RetroBrew Computers Forum File Attachments 1) Omega-Mainboard-Schematic-0.5.pdf, downloaded 367 times

Subject: Re: MSX2 Compatible Computer Project Posted by ajacocks on Tue, 11 Dec 2018 19:08:56 GMT View Forum Message <> Reply to Message You both have got my excitement going. The MSX was one of those machines that I heard about, back in the early 90s, but never saw, so it was somehow unreal.

I'd truly love to build one.

- Alex

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Tue, 11 Dec 2018 19:18:25 GMT View Forum Message <> Reply to Message Nice, I'll give the schematic a thorough look!

Meanwhile I've got the my 'Duo Sound' audio board working nicely after modifying the opamp resistors. The first revision floppy board is working but I already got rev 2 back from the pcb fab in China (3 day turnaround!.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Tue, 11 Dec 2018 19:20:49 GMT View Forum Message <> Reply to Message lintweaker - I am glad to hear about your progress! Would you please share you sound output schematic (or compare it vs. mine)? Also, what do you do for the video output? Do you have any buffers/transistors on the VDP RGB/Sync outputs, or you feed them directly to the VGA?

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Tue, 11 Dec 2018 19:27:31 GMT View Forum Message <> Reply to Message @Sergey, quick reply: I am using dual 4558 opamps based on the 'Expert3' schematic. Somehow the amplification was way too high (+10/-10V output instead of more like +2/-2V). I'll post the schematic later. for video I am using a Sony CXA1645. It needs a lot of external components but gets my SVIDEO,

Page 34 of 148 ---- Generated from RetroBrew Computers Forum CVBS and RGB. I am planning on using a Sony V7040 as well for a future genlock/superimpose option but it needs some un-optanium 180ns delay line and a band pass filter.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Fri, 18 Jan 2019 03:48:29 GMT View Forum Message <> Reply to Message My MSX compatible keyboard PCBs have arrived. I built one, and my son tested it using a USB HID firmware he wrote for an Arduino Micro.

In case someone wants to build one, I have several PCBs available for $20 + shipping. I hope I'll find large enough envelopes to send these PCBs File Attachments 1) Omega_Keyboard-PCB.jpg, downloaded 467 times 2) Omega_Keyboard-Building.jpg, downloaded 413 times 3) Omega_Keyboard-Complete.jpg, downloaded 472 times 4) Omega-Keyboard-Schematic-1.0.pdf, downloaded 364 times

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Fri, 18 Jan 2019 07:26:22 GMT View Forum Message <> Reply to Message Sergey wrote on Thu, 17 January 2019 19:48My MSX compatible keyboard PCBs have arrived. I built one, and my son tested it using a USB HID firmware he wrote for an Arduino Micro.

In case someone wants to build one, I have several PCBs available for $20 + shipping. I hope I'll find large enough envelopes to send these PCBs

Nice! I would not mind building one! What is a good source for the switches and keys?

Subject: Re: MSX2 Compatible Computer Project Posted by pbirkel on Fri, 18 Jan 2019 08:25:15 GMT View Forum Message <> Reply to Message Sergey wrote on Thu, 17 January 2019 19:48My MSX compatible keyboard PCBs have arrived. I built one, and my son tested it using a USB HID firmware he wrote for an Arduino Micro.

In case someone wants to build one, I have several PCBs available for $20 + shipping. I hope I'll find large enough envelopes to send these PCBs

I'd like one please. Also info about the switches and keycaps. Looks really nice :-}.

Page 35 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by ajacocks on Fri, 18 Jan 2019 08:27:10 GMT View Forum Message <> Reply to Message I'd like one, as well.

- Alex

Subject: Re: MSX2 Compatible Computer Project Posted by gkaufman on Fri, 18 Jan 2019 09:56:06 GMT View Forum Message <> Reply to Message If there's a spare PCB I'd like one as well.

- Gary

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Fri, 18 Jan 2019 21:43:18 GMT View Forum Message <> Reply to Message I published the BOM for the keyboard here here: https://github.com/skiselev/omega/blob/master/Keyboard.md The keyboard uses Cherry MX switches. The BOM includes linear (non-clicky) switches... they are better for games But feel free to get another type of Cherry MX switches if you like to. I've used a cheap set of Cherry MX compatible keycaps of the Amazon (about $12). There is quite a selection of these available on Amazon and other places. Note that the keyboard uses a rectangular Enter/Return key.

There are a few minor issues you should be aware of: 1. Pull up resistors are missing on COLUMN_0, COLUMN_2, and COLUMN_4 outputs. Add a 4.7k or so pull-up when using this keyboard. 2. The polarity of LEDs integrated in Caps Lock and Kana keys doesn't seem to match the marking on the MX key. Then assembling the keyboard, please verify that the LEDs are connected properly. 3. 1.6 mm PCB feels a bit flimsy. This probably will be less of an issue when the PCB is mounted on a rigid panel. Or alternatively it is possible make a metal plate and mount MX switches on that plate.

I am still figuring out the shipping details. I'll update this thread soon with the shipping prices and information.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Sat, 19 Jan 2019 09:25:43 GMT

Page 36 of 148 ---- Generated from RetroBrew Computers Forum View Forum Message <> Reply to Message Thanks for the BOM, keycaps are on order from Amazon. Hopefully I can find a japanese layout later to better match my Japanese BIOS ROMs.

Subject: Re: MSX2 Compatible Computer Project Posted by andrii_kutepov on Sun, 20 Jan 2019 14:10:15 GMT View Forum Message <> Reply to Message I'd like one pcb, as well.

Subject: Re: MSX2 Compatible Computer Project Posted by etchedpixels on Sun, 20 Jan 2019 14:15:08 GMT View Forum Message <> Reply to Message Also interested in the keyboards if you have any left.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Sun, 20 Jan 2019 22:30:15 GMT View Forum Message <> Reply to Message Hello Sergey, Add me in the list for another keyboard PCB when they are available. The item is not yet in the inventory. J. S.

Subject: Re: MSX2 Compatible Computer Project Posted by ABurrows on Mon, 21 Jan 2019 22:49:50 GMT View Forum Message <> Reply to Message Hi Sergey,

What is the status of this project?

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 23 Jan 2019 00:20:46 GMT View Forum Message <> Reply to Message I appreciate all the interest. I am traveling this week, so I am not able to mail any PCBs. I'll be ready to send them early next week. I'll post a reply here at that time.

Page 37 of 148 ---- Generated from RetroBrew Computers Forum I have 18 PCBs available, so it should be enough for anyone who had been interested so far.

Thanks!

Subject: Re: MSX2 Compatible Computer Project Posted by ABurrows on Wed, 23 Jan 2019 00:37:58 GMT View Forum Message <> Reply to Message can you please put me down for one board Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 30 Jan 2019 18:15:37 GMT View Forum Message <> Reply to Message I apologize for the delay. I am ready to ship the Keyboard PCBs now. I've updated the inventory page accordingly. The price for the PCB is $15. The shipping for a single PCB is $6 in the US, and $15 anywhere else in the world. (Note, it is a fairly big board 334 mm x 125 mm, and it will be shipped in a big 15" x 11" mailer)

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Wed, 30 Jan 2019 18:20:42 GMT View Forum Message <> Reply to Message Sergey wrote on Wed, 30 January 2019 10:15I apologize for the delay. I am ready to ship the Keyboard PCBs now. I've updated the inventory page accordingly. The price for the PCB is $15. The shipping for a single PCB is $6 in the US, and $15 anywhere else in the world. (Note, it is a fairly big board 334 mm x 125 mm, and it will be shipped in a big 15" x 11" mailer) Great! Count me 1 for one, shipping to Europe.

Subject: Re: MSX2 Compatible Computer Project Posted by pbirkel on Wed, 30 Jan 2019 18:40:22 GMT View Forum Message <> Reply to Message Sergey wrote on Wed, 30 January 2019 10:15I apologize for the delay. I am ready to ship the Keyboard PCBs now. I've updated the inventory page accordingly. The price for the PCB is $15. The shipping for a single PCB is $6 in the US, and $15 anywhere else in the world. (Note, it is a fairly big board 334 mm x 125 mm, and it will be shipped in a big 15" x 11" mailer)

Funds sent!

Page 38 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Wed, 30 Jan 2019 18:43:58 GMT View Forum Message <> Reply to Message I think I am missing something. How is the ordering suppose to work? edit: e-mail sent

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Sat, 09 Feb 2019 16:18:28 GMT View Forum Message <> Reply to Message Got the Omega keyboard PCB today, thanks Sergey!

The keys with support are a bit of a hassle. They have a bit less travel than the normal keys. But I am a happy camper, the keyboard works beautifully on my DIY MSX(2+)!

Now I need to convert my MSX1,2 and 2+ BIOS to ones with a international keyboard instead of Japanese (I've been searching for the correct Japanese keycaps but so far did not find any)

Subject: Re: MSX2 Compatible Computer Project Posted by ajacocks on Tue, 04 Jun 2019 13:47:00 GMT View Forum Message <> Reply to Message I just wanted to check in, and see if Sergey had made any more progress on the MSX2. I have all the parts for the keyboard, but haven't built it, yet.

- Alex

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Tue, 04 Jun 2019 14:11:34 GMT View Forum Message <> Reply to Message Actually, I was working on the PCB routing just over the last weekend. There are still about 80 nets to route. It takes time.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Tue, 04 Jun 2019 15:04:44 GMT View Forum Message <> Reply to Message Nice!

Page 39 of 148 ---- Generated from RetroBrew Computers Forum Thanks for the update. Come on!, I can not wait to have mine.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Thu, 06 Jun 2019 17:17:14 GMT View Forum Message <> Reply to Message Good to see you're still working on it. Looking forward seeing the results!

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 09 Sep 2019 22:12:50 GMT View Forum Message <> Reply to Message Hi,

I am done with the main board PCB layout, and I am doing the final review. I'll be ordering the PCBs soon, hopefully later this week. The current schematic and PCB layout are attached here. They are also available at the project's GitHub repo: https://github.com/skiselev/omega (under Mainboard directory).

Please take a look. Let me know if you see any issues.

Thanks, Sergey File Attachments 1) Omega-Mainboard-Board-0.9.pdf, downloaded 169 times 2) Omega-Mainboard-Schematic-0.9.pdf, downloaded 202 times

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Tue, 10 Sep 2019 00:09:20 GMT View Forum Message <> Reply to Message Looking good Sergey! I'm really looking forward to this build. Once it's ready for a real run I could probably even design a case for it, for 3D printing. Below is an example of the last one that I did, for the Harlequin clone. But your board will be a little more fun, with openings and brackets for the keyboard. What are you board dimensions right now? I'm limited to 200x200x200mm, but I'm getting ready to upgrade to a larger machine. In either case, I could also design it to print in halves or thirds.

Page 40 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by ajacocks on Tue, 10 Sep 2019 00:33:48 GMT View Forum Message <> Reply to Message Woohoo! It's great to see your project on this machine.

- Alex

Subject: Re: MSX2 Compatible Computer Project Posted by b1ackmai1er on Tue, 10 Sep 2019 11:20:57 GMT View Forum Message <> Reply to Message Hi Doug,

Love the keyboard enclosure and the keycaps. Have you considered taking the enclosure up to the base of the keycaps?

How long does it make? Does it require a lot of "finishing"? Wondering how this would look in a hammertone paint finish.

Regards Phil.

Subject: Re: MSX2 Compatible Computer Project Posted by b1ackmai1er on Tue, 10 Sep 2019 12:42:45 GMT View Forum Message <> Reply to Message Hi Sergey,

This looks so good.

While admiring your routing I noticed you could straighten out traces A4 & RESET between P6 and P5 of the 82C55.

Can this be switched between NTSC/PAL or do you have to select at component level i.e. crystal selection and video chip.

Was wondering if VCC to the cartridges was sufficient since it is right at the end of the trace line and homebrewers may be plugging all sorts of customer cartidges in.

Regards Phil

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Tue, 10 Sep 2019 16:36:24 GMT View Forum Message <> Reply to Message

Page 41 of 148 ---- Generated from RetroBrew Computers Forum b1ackmai1er wrote on Tue, 10 September 2019 04:20Hi Doug,

Love the keyboard enclosure and the keycaps. Have you considered taking the enclosure up to the base of the keycaps?

How long does it make? Does it require a lot of "finishing"? Wondering how this would look in a hammertone paint finish.

Regards Phil. Phil,

With this particular design it wasn't practical, since the case is the keyboard, the switches are hand wired. But on something like the omega, having a keyboard PCB allows for recessing the switches. And that is how I would design it.

Concerning fit and finish, it didn't require any more than any other painted project. Since the parts are 3D printed, it really comes down to the capabilities of your machine. But I heat welded the halves, filled and sanded, primed, then painted with a semi gloss enamel. The more you do the better it will look. Although I can't speculate on the hammertone, I'm not familiar with that finish.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Tue, 10 Sep 2019 23:32:26 GMT View Forum Message <> Reply to Message Hi Phil,

Thank you for your feedback! b1ackmai1er wrote on Tue, 10 September 2019 05:42I noticed you could straighten out traces A4 & RESET between P6 and P5 of the 82C55.

Fixed! b1ackmai1er wrote on Tue, 10 September 2019 05:42Can this be switched between NTSC/PAL or do you have to select at component level i.e. crystal selection and video chip.

It has to be selected using jumpers/wire links - JP4 and JP5 particularly. Also while NTSC uses the clock generated by VDP, PAL requires a separate clock generated using an additional crystal Y3 and U43. b1ackmai1er wrote on Tue, 10 September 2019 05:42Was wondering if VCC to the cartridges was sufficient since it is right at the end of the trace line and homebrewers may be plugging all sorts of customer cartidges in.

I've increased VCC trace width twofold - from 1 mm to 2mm. Hopefully that would suffice...

Best regards,

Page 42 of 148 ---- Generated from RetroBrew Computers Forum Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Tue, 10 Sep 2019 23:38:16 GMT View Forum Message <> Reply to Message Hi Doug,

Nice case... I've initially 3D printed case for my own Harlequin build. It took more than 24 hours if I recall correctly. Unfortunately in my case I had some wrapping on the edges, and it didn't look too good. So eventually I've purchased an injection molded case with the membrane keyboard. I bet the mechanical keyboard feels nicer and works better than my membrane keyboard :)

The mainboard size is 150 mm x 330 mm. Perhaps it could be printed in two halves.

Thanks, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Tue, 10 Sep 2019 23:58:13 GMT View Forum Message <> Reply to Message Hi,

I've made a few small changes to the design and ordered 10 PCBs. Next, once I have the PCBs, I'll gradually build and test the board. As usual, the updated design is in the project's GitHub repo: https://github.com/skiselev/omega

Thanks, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Wed, 11 Sep 2019 00:16:51 GMT View Forum Message <> Reply to Message Sergey wrote on Tue, 10 September 2019 16:38Hi Doug,

The mainboard size is 150 mm x 330 mm. Perhaps it could be printed in two halves.

Page 43 of 148 ---- Generated from RetroBrew Computers Forum Thanks, Sergey

Sergey,

I followed your build when you did the Harlequin. And saw that you had printed a case, but I don't remember you mentioning the warping. It is a real problem when using abs. This case was printed in PLA. So warping wasn't an issue. However, I do need to finish a bed upgrade on my bed. I started a MK2 upgrade on my Da Vinci Pro. But the supports I printed are not holding up to the bed temp I'd like to maintain. So once that is fixed I plan on trying with ABS.

As for the bed size vs case size, it sounds doable. It'll be a tight fit in halves, but I guess about 150x175 print size would be a ballpark estimate. The case should be fairly easy depending on layout. I'll have to wait until you have boards ready before I could really start drawing anything up. So I'll wait on you to verify it before committing, since you may need to make some changes to layout.

As for the Harlequin keys, they're great! But I don't have any real reference for the speccy, only the ZX81 (more precisely the TS1000). Touch typing is a bit awkward due to the layout of the keyboard. But it's not too terrible. I plan on a slight redesign adding holes for a reset switch and a bank switch for the ROM's A14 line. But other than that, I've very happy with it. I can share the STLs if you're interested. But I'll stop there, as I'm getting pretty far off topic of the thread, and it's only meant as a reference to the fact I enjoy creating things like that.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Thu, 26 Sep 2019 16:32:45 GMT View Forum Message <> Reply to Message Hi,

Here is the project status update:

I've received the PCBs. I've compiled a preliminary Bill of Materials I've soldered most of the components, or in case of ICs - sockets, that are required for minimal test configuration. I am waiting for some components from Mouser, as it turned out I haven't ordered everything I need for this project just yet :) The next steps are to complete that minimal configuration - VDP, Z80, memory, PPI, slot/paging logic, SPLDs, timing logic, keyboard, and test and debug that configuration. Once it is working, I'll gradually add other components: Video circuitry, PSG, slots' buffers, printer control, cassette tape recorder support, and so on. So far I've found a few issues, all related to the silkscreen, they are documented in Known Issues section.

Here is the photo of the board so far:

Page 44 of 148 ---- Generated from RetroBrew Computers Forum Cheers, Sergey File Attachments 1) Omega-Mainboard-Half_Built.jpg, downloaded 1405 times

Subject: Re: MSX2 Compatible Computer Project Posted by ajacocks on Thu, 26 Sep 2019 16:48:16 GMT View Forum Message <> Reply to Message Looks fantastic, Sergei!

I can't wait to build this machine.

- Alex

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Thu, 26 Sep 2019 18:17:22 GMT View Forum Message <> Reply to Message Hi,

Looks very nice! good luck with testing!

Subject: Re: MSX2 Compatible Computer Project Posted by andrii_kutepov on Fri, 27 Sep 2019 08:14:04 GMT View Forum Message <> Reply to Message It's perfect, like everything Sergey does. I'm looking forward to the end of the tests. Already bought a timer and VDP chip on ebay

Subject: Re: MSX2 Compatible Computer Project Posted by etchedpixels on Fri, 27 Sep 2019 09:18:18 GMT View Forum Message <> Reply to Message Awesome, definitely interested.

And I'm going to have to go finish the MSX1 Fuzix port 8)

Page 45 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by andrii_kutepov on Sat, 28 Sep 2019 12:19:05 GMT View Forum Message <> Reply to Message Sergey, Please correct the link to the project on the mouser. Project Access ID:ffffffffff is not correct.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Sun, 29 Sep 2019 20:34:33 GMT View Forum Message <> Reply to Message Andrii,

The BoM is still changing as I am testing and debugging the board. Please wait until I have it working :)

Thanks, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 30 Sep 2019 17:00:44 GMT View Forum Message <> Reply to Message Hi,

I've spent some a few hours this weekend trying to debug the main board. The process somewhat complicated due to lack of a "printf" output device. So I had to connect a TIL311 to the printer port instead :)

I found some (really beginner's) mistakes in the schematic:

74*32 pinout was incorrect... well, not exactly incorrect. It was correct for "De Morgan" normal symbol (positive logic OR), but incorrect for "De Morgan" convert symbol (negative logic / NAND with inverted inputs). As the result there's 11 OR gates that have 22 incorrect connections. I had to patch my system, cutting multiple traces and soldering a bunch of wires. The funny thing is that I am using a custom library exactly because while ago KiCad library had some pinout issues. Swapped /RD and /WR lines in the subslot register read/write decoder. "Fortunately" the fix didn't require cutting additional traces... the traces were already cut while fixing the previous issue. I just had to re-solder a couple of wires.

Page 46 of 148 ---- Generated from RetroBrew Computers Forum After fixing these issues the system seems to get stuck at enumerating expanded slots. That's the next thing to debug.

Also, the right angle keyboard header seems to interfere with printer port latch. Gotta use straight header instead...

Thanks, Sergey File Attachments 1) Omega-Mainboard-POST.jpg, downloaded 1357 times 2) Omega-Mainboard-Rework.jpg, downloaded 1353 times

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Mon, 30 Sep 2019 18:43:53 GMT View Forum Message <> Reply to Message Nice progress, do/did you use a logic analyzer? I found it a very useful tool debugging where the system gets stuck and seeing the board actually executing Z80 code.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 30 Sep 2019 22:52:11 GMT View Forum Message <> Reply to Message I do have a mixed signal oscilloscope. I didn't have to use the logic analyzer on this board just yet. Oscilloscope on the other hand was quite useful in the initial troubleshooting. Now the board is fetching and running the code from ROM. I still have to determine if the issue that I am seeing now is related to RAM access. The RAM implementation in MSX2 is quite complex - it involves two slot decoders (primary and expanded) and paging.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Tue, 01 Oct 2019 17:52:00 GMT View Forum Message <> Reply to Message Found another silly issue... Apparently V9938 VDP /INT output is an open drain output, but I don't have a pull-up on it. As the result it reads as "LOW", which causes an interrupt right after the first EI instruction. That's why it was getting stuck at, or rather at the end of enumerating expanded slots subroutine.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Tue, 01 Oct 2019 18:20:58 GMT

Page 47 of 148 ---- Generated from RetroBrew Computers Forum View Forum Message <> Reply to Message Ha! good catch! My board has a pullup on the /INT line on the Z80 end so I never encountered that issue (your design allows for a seperate /INT from the slots as it should, my design omits the feature) Does slot enumeration now work? It sounds like your getting close on MSX bootup...You can always try to boot MSX1 which is a bit simpler

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Tue, 01 Oct 2019 18:30:51 GMT View Forum Message <> Reply to Message Yes, the slot enumeration seems to work. It worked before too. It just there is an EI at the end of the slot enumeration. Frankly, I am not quite sure why check_expanded subroutine in C-BIOS has an DI/EI around it. The interrupts are disabled anyway at reset. The first instruction of C-BIOS is DI. And they get enabled later on. And check_expanded is only called during the initialization. They could have saved two bytes on these DI/EI! :)

I'll connect a pull-up to VDP later today, and will continue working on debugging the board.

On an unrelated note, I am wondering how useful the printer port is... Perhaps I should replace it with a WD37C65 FDC?

Subject: Re: MSX2 Compatible Computer Project Posted by martin8bity on Tue, 01 Oct 2019 19:24:26 GMT View Forum Message <> Reply to Message Great to see, that it becomes alive. I think the FDC could be more useful than a printer port, if it will fit on board.

Subject: Re: MSX2 Compatible Computer Project Posted by etchedpixels on Tue, 01 Oct 2019 21:58:11 GMT View Forum Message <> Reply to Message The FDC on an MSX machine normally goes in a cartridge. It's usually memory mapped at 0x4000 with the cartridge 16K space holding the MSXDOS and the MMIO for it just to ensure that combined with subslots it's as painful as possible to program - like all MSX it was designed by a sadist who hated programmers ;)

Alan

Page 48 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Tue, 01 Oct 2019 22:30:22 GMT View Forum Message <> Reply to Message Right... potentially it is possible to map the FDC itself to the I/O space (instead of memory), and use one of the subslots for the Disk ROM. My design allows mapping Flash ROM to any subslot. More work though, as I'll need to disassemble one of these WD37C64 Disk ROMs and replace all the MMIO LDs with IN/OUT.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 02 Oct 2019 02:57:51 GMT View Forum Message <> Reply to Message Good news are that after connecting a pull-up to VDP /INT the system no longer getting stuck at EI. In fact according to my POST display it boots all the way and gets stuck not finding any ROMs to boot from. The not so good news are that I still don't have any display. Nothing on V9938 VDP RGB and VIDEO pins. There's ~127 kHz signal on CSYNC and HSYNC instead of expected ~14.59 kHz. Also the /INT frequency is about 250 Hz instead of expected 60 Hz. I am wondering if C-BIOS doesn't initialize VDP correctly (e.g. skips initializing some essential registers)? I've checked the VDP wiring, compared it to other designs and I haven't find any issues. I also checked that chip select is generated, and in fact I can even see VDP writing to VRAM, apparently when BIOS is clearing the screen.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Thu, 03 Oct 2019 18:52:21 GMT View Forum Message <> Reply to Message It boots!

Well, kind of. It appears that VDP does get configured properly once in a while (every 5th attempt or so). I still haven't figured out why it doesn't get configured properly other times. I had a suspicion that /RESET gets asserted for too short time. Although, according to ADM693 datasheet the reset is active for 200 ms, and according to V9938 datasheet it needs only 10 ms reset pulse. I've also tried connecting VDP /RESET to the RS flip-flop that deactivates slot selection at power on, which gets reset the first time PPI is accessed. That didn't seem to help. So it might not be the RESET after all. Another suspicion is power supply. I use 5 V / 2.5 A regulated wall type power supply. It might be that the voltage drop is too big.... Anyway, that's the next thing I am going to check.

Page 49 of 148 ---- Generated from RetroBrew Computers Forum I'd appreciate any ideas on this VDP issue.

Other than that I've spent some time ironing out the SYNC signal generation. On V9938 CSYNC is a "three level" signal. This actually means that the logic low is about 2.8V and logic high is about 4.8V. CXA1645 encoder expects TTL level sync signal. So I had to re-purpose Q2 and use one of optional 74HCT04 gates to generate the proper SYNC signal.

For the folks that want to use RGB output. Any idea what HSYNC level in this case should be? It appears that VGA has a TTL level sync. If that's true, I can just output the SYNCIN to the RGB connector...

Cheers, Sergey

File Attachments 1) CSYNC.png, downloaded 1198 times 2) Omega-First_Boot.jpg, downloaded 1248 times

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Fri, 04 Oct 2019 07:21:48 GMT View Forum Message <> Reply to Message Good to see that familiar screen! I am not sure if the V9958 is different wrt CSYNC. I am also using the CX1645, I did not encounter issues with SYNC.

Excerpt from my video board:

File Attachments 1) v9958-cx1645p-excerpt.png, downloaded 139 times

Subject: Re: MSX2 Compatible Computer Project Posted by martin8bity on Fri, 04 Oct 2019 07:48:00 GMT View Forum Message <> Reply to Message Try different 9938/9958. I do not know the source, but there is a lot of the second quality ICs on eBay, that have peculiar problems.

Subject: Re: MSX2 Compatible Computer Project

Page 50 of 148 ---- Generated from RetroBrew Computers Forum Posted by Sergey on Fri, 04 Oct 2019 13:41:16 GMT View Forum Message <> Reply to Message Jurgen: My CSYNC level shifter works just fine. I assume it will also work with V9958, although in this case it is possible to bypass it. I am wondering if you're outputting the sync signal(s). And if so, what signals and voltage levels (e.g. VGA needs both VSYNC and HSYNC in TTL levels, SCART uses composite sync at 0.7V or so level, but apparently it can get sync from composite video too)

Martin: I've tried 3 VDPs. I believe I bought them in three different opportunities from different sellers. I also think that I bought them from US and not China. All behave similarly.

Some other updates: - The boot success rate is better than I thought. So I can "reliably" boot the system from the second or the third try... Might be a power thing, although I haven't tested that just yet. - I found yet another silly error. This time in PSG clock divider... I've got /CLK and D inputs swapped on a 74HCT74 - And yet another (not so silly) PSG issue... I've used a single power supply op amp for the filter, and it needs a virtual ground (2.5V signal). I've connected a real ground instead. The sound output is not working as the result. - The slots work! At least that Vampire Killer cartridge that I have plays nicely :) - It had been brought to my attention that the slot connectors need to be rotated 180 degrees. That would require some considerable board rerouting.

That's all for this morning. Have a great weekend! - Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Fri, 04 Oct 2019 15:05:32 GMT View Forum Message <> Reply to Message Sergey wrote on Fri, 04 October 2019 15:41 Jurgen: My CSYNC level shifter works just fine. I assume it will also work with V9958, although in this case it is possible to bypass it. I am wondering if you're outputting the sync signal(s). And if so, what signals and voltage levels (e.g. VGA needs both VSYNC and HSYNC in TTL levels, SCART uses composite sync at 0.7V or so level, but apparently it can get sync from composite video too)

I am not using a 'real' VGA output. I do not have a VGA monitor that still works with a 15kHz signal, although I use a VGA connector for output with RGB and COMP as sync signal. I can switch COMP between composite video and VDP csync. With the VGA connector I am using a VGA-to-SCART cable which has an additional USB connector for the switch signal. This then goes to a cheap SCART to HDMI converter. An other

Page 51 of 148 ---- Generated from RetroBrew Computers Forum option is a VGA 'scan doubler'.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Sat, 05 Oct 2019 04:16:21 GMT View Forum Message <> Reply to Message https://youtu.be/P6nD6vv4WaA

Jurgen: I have an 8 pin Mini DIN connector for everything video and audio. I suppose I'll add composite video there along with RGB.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Thu, 10 Oct 2019 00:23:28 GMT View Forum Message <> Reply to Message Yet another update. I've fixed the issues I found so far, and I rerouted the PCB to rotate cartridge slots 180 degrees. This actually also simplified the routing, as I didn't have to route the data bus all the way to the right side of the board. Other changes include swapping DB25 printer connector to MSX standard Micro Ribbon 14-pin connector (aka Centronics).

I would really appreciate if few of you would take a look at the schematic and the PCB design, and report any issues you'll find.

Latest updates are on GitHub: https://github.com/skiselev/omega/blob/master/Mainboard.md

I'll also will do a few more checks, and also test the joystick and cassette recorder functionality on my v1.0. And then I'll order another set of PCBs.

Thanks, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by martin8bity on Thu, 10 Oct 2019 13:48:15 GMT View Forum Message <> Reply to Message Did you find the "boot success rate" or "VDP initialization" issue reason?

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Thu, 10 Oct 2019 16:13:05 GMT

Page 52 of 148 ---- Generated from RetroBrew Computers Forum View Forum Message <> Reply to Message martin8bity wrote on Thu, 10 October 2019 06:48Did you find the "boot success rate" or "VDP initialization" issue reason? Kind of. It is definitely power related. First of all it seems that 5 x 47 uF bypass capacitors on 5V rail is a bit too much. This causes the voltage to ramp-up slowly, especially given that I use a 5V "wall wart" type of power supply with a fairly long cable. I've removed all these capacitors, except the one closest to the power jack. Now board boots almost 100% of the time. And if it doesn't a short off/on fixes the situation. Next, the power supervisor which I am using (ADM693) has a typical reset voltage of 4.4 V, while VDP shows minimal voltage of 4.75 V. I've ordered ADM691 instead, which has a higher reset voltage of 4.65 V. The 0.1 V difference hopefully is not a big issue, since there is a delay between power reaching 4.65 V and reset signal.

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Wed, 30 Oct 2019 07:56:39 GMT View Forum Message <> Reply to Message Very excited to build this project when everything is finalized. I've got boards for an N8 and a Harlequin 128 to build in the meantime, but an MSX2 has been a holy grail computer for me for a long time.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 30 Oct 2019 16:46:20 GMT View Forum Message <> Reply to Message One more update. Yesterday I went ahead and ordered version 1.1 PCBs. This version fixes all the known issues found so far, and hopefully it won't introduce any new ones :) The GitHub repository has been updated with the new design files. I also have updated the documentation. Of course it can use more work, as for example it doesn't really describe how to generate Flash ROM images.

I'll build and test the board once I get the PCBs - probably some time next week.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Fri, 01 Nov 2019 09:16:43 GMT View Forum Message <> Reply to Message Nice! You've been busy :)

I am busy with my very first MSX cartridge, if it works it could make a nice companion for the Omega. The cartridge can be used as a (virtual) disk drive using a Rasperry Pi Zero as master. The boards just arrived yesterday, I'll put one together this weekend...fingers crossed it works...

Page 53 of 148 ---- Generated from RetroBrew Computers Forum BTW the project is based on smbaker's "Raspberry Pi Virtual Floppy for ISA (PC XT/AT) Computers"

Added a picture of the current state:

File Attachments 1) msx-vdisk-pi-zero-no-flash-640.jpg, downloaded 836 times

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Fri, 08 Nov 2019 08:17:40 GMT View Forum Message <> Reply to Message I was just poking around on ebay checking the prices on 9938s, and for some reason they're significantly more expensive than 9958s. The 9958 isn't pin compatible but the modification is apparently relatively simple (it's an extremely common upgrade), but I was wondering why you chose the 9938 over the 9958?

Of course, it is entirely possible that we've created a small price bubble in anticipation of building this board. :d

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Fri, 08 Nov 2019 20:16:27 GMT View Forum Message <> Reply to Message Quote:I was just poking around on ebay checking the prices on 9938s, and for some reason they're significantly more expensive than 9958s. The 9958 isn't pin compatible but the modification is apparently relatively simple (it's an extremely common upgrade), but I was wondering why you chose the 9938 over the 9958? The Omega board actually supports both V9958 and V9938 VDPs. And I personally would recommend V9958 over V9938 because it provides better video quality, and has some additional (MSX2+) features.

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Sat, 09 Nov 2019 11:08:27 GMT View Forum Message <> Reply to Message Another question: Given that the owner of the MSX standard has agreed that it's all freely available, and said that you owe a $1 debt to Microsoft for using MSX basic (i defy you to find someone in microsoft who would not turn around and say 'we don't need your dollar'), what obstacle is there for you for providing a generic compatible MSX2+ bios? Just don't brand it with the MSX logo.

Page 54 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Sun, 10 Nov 2019 00:04:56 GMT View Forum Message <> Reply to Message Quote:what obstacle is there for you for providing a generic compatible MSX2+ bios? I don't really feel like getting into a legal hurdle with Microsoft and whoever owns the MSX stuff now. So I don't plan to distribute MSX2 BIOS or BASIC. The open source alternative (C-BIOS) is available. Also there are plenty of places on the internet one can get MSX2 ROMs. I plan to provide a script to create the ROM image using either one of these options.

Quote:Given that the owner of the MSX standard has agreed that it's all freely available In an interview to someone? There is no official statement. There's no place where MSX binaries or source code had been officially released.

Quote:you owe a $1 debt to Microsoft for using MSX basic Where do I put that dollar? But seriously. I personally don't feel like I owe anything for using 30+ old piece of software for recreational and non profit purposes, that hasn't been a money maker for the company for at least 25 last years. Yet, it is quite possible that some patent troll representing MSX will go after me, just because there is "MSX" string somewhere in the binaries.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Sun, 10 Nov 2019 00:31:17 GMT View Forum Message <> Reply to Message I have some good news: I've built and tested Omega Mainboard v1.1, and it is working properly.

I made many updates to the documentation, including the bill of materials. Please read it, and the next "Configuration options" session carefully before ordering parts. Let me know if you have any questions or comments.

For those of you who expressed an interest in building Omega, I have a dozen extra PCBs available for $20 each. With that being said I am traveling next week and I won't be able to mail anything. So please hold on your orders until I am back (November 16th).

File Attachments 1) Omega-Mainboard-1.1-Stacked.jpg, downloaded 835 times 2) Omega-Mainboard-1.1-Back.jpg, downloaded 804 times 3) Omega-Keyboard_and_Mainboard-1.1.jpg, downloaded 819 times

Subject: Re: MSX2 Compatible Computer Project

Page 55 of 148 ---- Generated from RetroBrew Computers Forum Posted by jdgabbard on Sun, 10 Nov 2019 01:13:12 GMT View Forum Message <> Reply to Message Sergey,

That looks great! Looks like I have something to build in the not too distant future!

Subject: Re: MSX2 Compatible Computer Project Posted by pbirkel on Sun, 10 Nov 2019 06:10:38 GMT View Forum Message <> Reply to Message Very nice! PM sent with my PCB request, when you return :-}.

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Sun, 10 Nov 2019 08:49:06 GMT View Forum Message <> Reply to Message Quote:Quote:Given that the owner of the MSX standard has agreed that it's all freely available In an interview to someone? There is no official statement. There's no place where MSX binaries or source code had been officially released. Given that this project is 'build-your-own' and in theory teaches people how the various parts work with each other, you should drop a line to the man who did the interview and try to get in touch with Nishi-san himself. I think this project would tickle his fancy.

Frankly, we should let him know about all of what retrobrew does, I think he'd appreciate the existence of a place like this, a community of old school hackers.

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Sun, 10 Nov 2019 09:00:48 GMT View Forum Message <> Reply to Message now I want to call microsoft and ask them where i can send my dollar

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Mon, 11 Nov 2019 12:53:44 GMT View Forum Message <> Reply to Message Hi people. there's another MSX project witch you can buy to Eugeny Brychkov who includes MSX official license. maybe you can ask him. here you are the project: http://www.gr8bit.ru/what-is-gr8bit.htm

Page 56 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Mon, 11 Nov 2019 16:28:02 GMT View Forum Message <> Reply to Message Sergey,

I've been looking over the schematic on your GitHub page. But I'm having a problem in understanding where you're generating the 3.58mhz clock. Looks like you have an optional PAL clock. And that you generate the frequency for the VDP as well as the RTC. But I'm not seeing where on the schematic you are generating this signal from. I'm guessing that you're probably dividing the 21.477270mhz clock by 6. But I'm not actually seeing it on the schematic. What am I missing here? jordi.solis wrote on Mon, 11 November 2019 04:53Hi people. there's another MSX project witch you can buy to Eugeny Brychkov who includes MSX official license. maybe you can ask him. here you are the project: http://www.gr8bit.ru/what-is-gr8bit.htm I'm familiar with that project. But not sure how it's really relevant to this thread...other than they are both duplicating the MSX standard. I agree that it would be nice to have a sanctioned bios. But considering Sergey doesn't seem interested in jumping through the hoops required to try and obtain the licensing from ASCII or Microsoft, and there is another option (C-Bios), as well as two known compatible bios (Sanyo PHC-23J and Philips NMS 8250) according to the documentation, this is a moot point in my opinion. And while the gr8bit might be neat in that it can be shoved into a ATX computer case, whereas this currently doesn't have a case. But even this point is not a huge issue, as I am planning on designing a 3D-printable case for this computer and releasing the design files for any who wish to build it. Of course any number of others could also submit their own designs...it's nice to have options. Then there is the issue that with the amount of PCBs required to build the gr8bit, I hazard a guess that it would ultimately be a little more expensive to get up and running. (Just checked, $499 for the kit... Quite a bit more expensive) Not to mention it is at least partially emulating hardware with FPGAs. It just seems like that project has completely different goals to this one. What Sergey has done here is a clone that is faithful to the original in spirit and design.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Mon, 11 Nov 2019 16:56:07 GMT View Forum Message <> Reply to Message jdgabbard wrote on Mon, 11 November 2019 17:28Sergey,

Page 57 of 148 ---- Generated from RetroBrew Computers Forum The (CPU) clock signal is generated by the VDP from the 21.x MHz crystal.

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Mon, 11 Nov 2019 18:01:49 GMT View Forum Message <> Reply to Message gr8bit isn't too relevant to this project, but the fact that the man who is control of the MSX licensing and the BIOS for it is open minded to hobbyist projects is definitely relevant. If you get in touch with him I'm sure he'll give the green light to using the MSX BIOS. He's given the green light to far more expensive FPGA systems in the past.

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Mon, 11 Nov 2019 18:59:19 GMT View Forum Message <> Reply to Message lintweaker wrote on Mon, 11 November 2019 08:56jdgabbard wrote on Mon, 11 November 2019 17:28Sergey,

The (CPU) clock signal is generated by the VDP from the 21.x MHz crystal.

Ok, that makes a little more sense now.

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Mon, 11 Nov 2019 19:00:58 GMT View Forum Message <> Reply to Message And that begs the question of whether part of the cost is due to the licensing... While I doubt it, with all the "Mini" retro consoles coming out in the last few years, I can't help but think there may be a similar effort on the MSX front.

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Mon, 11 Nov 2019 19:55:11 GMT View Forum Message <> Reply to Message

Page 58 of 148 ---- Generated from RetroBrew Computers Forum Well, I shot an email over to [email protected] to see if I could persuade them to release the MSX-BASIC source like they did with the DOS 1 & 2 last year. If they will release the MSX-BASIC code, that is one hurdle. Not to mention how important it is for computer history in general. Maybe someone could track down the current contact information for the MSX Licensing Corp. and we could send a request to them as well. Last I heard, all efforts to recommercialize the MSX have been halted due to the failure of the One-Chip-MSX. So they may be willing to just release it into the wild.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Tue, 12 Nov 2019 08:27:02 GMT View Forum Message <> Reply to Message hello lintkeaker! How was your virtual floppy project? Did you get it to work? In your post you told "it can be used as a (virtual) disk drive", does it mean we could have more uses just by programming that Raspberry? something like a wifi network interface? J. S.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Wed, 13 Nov 2019 16:36:18 GMT View Forum Message <> Reply to Message jordi.solis wrote on Tue, 12 November 2019 09:27hello lintkeaker! How was your virtual floppy project? Did you get it to work? In your post you told "it can be used as a (virtual) disk drive", does it mean we could have more uses just by programming that Raspberry? something like a wifi network interface? J. S. I am busy writing the BIOS code for the MSX side so I will appear as (a) normal (large)floppy drive(s). Luckily on the Pi side the existing code is very usable and is already working. With the hardware there are lots more possibilities as long the required software will be created. A wireless network interface is an example.

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Wed, 13 Nov 2019 20:49:06 GMT View Forum Message <> Reply to Message Sergey,

Forgive me, as I'm not very acquainted with the MSX architecture. Concerning compatibility with the PHC-23J and the NMS-8250, are any features lost when using one or the other? Specifically concerning the memory. My understanding of the MSX bios is that it automatically looks for memory in each slot/sub. However I see the the PCH doesn't have a mapper, while the NMS does

Page 59 of 148 ---- Generated from RetroBrew Computers Forum have a 128k mapper. Any issue with reading the full range of memory with these BIOS's? I doubt it would, but you never can tell what companies do when changing the bios for their own purpose. The reason I ask, is that while C-Bios is open source, it currently lacks 100% compatibility, and doesn't have cassette routines from what I read. So that would make the preferred BIOS of choice the NMS in my opinion.

Second question, as I understand it, most mappers allow you to control each 16k page in a Slot. But from what I'm reading in your documentation it would appear that you mapped this to a single 64k page in slot 3-2. Is that correct?

Subject: Re: MSX2 Compatible Computer Project Posted by etchedpixels on Wed, 13 Nov 2019 23:53:11 GMT View Forum Message <> Reply to Message MSX has three layers of memory management. It's the most broken, catastrophic fail of a design in that respect and that's why even many games don't work on every MSX.

In the beginning (pre MSX) each 16K bank could be one of four slots. Two GPIO bits select which. Almost nice and simple.

MSX1 extended this with a crazy hack that uses memory address 0xFFFF in each bank to further change which of four subslot chunks appear in each 16K slot. That's a nightmare because you then have to get 0xFFFF in the relevant slot mapped to change the subslot and do it without unmapping something you need. The ROM can do it for some banks only. To add to the excitement MSX1 didn't do the sane thing and decide where the RAM goes, so your RAM might be slot, subslot or smeared around several. That was apparently not painful enough so the disks and other I/O devices also use slots and subslots so that trying to copy data from 0x4000 in subslot 2 of slot 3 to an SD card with MMIO at 0x4000 in subslot 1 of slot 1 is a barrel of laughs.

MSX2 then puts a third layer (an actual vaguely sane banking system) for the RAM only on top of it all. It has to be back compatible so couldn't presumably replace the original misdesign. Thus you map the RAM (once you find it) into the right places and the mapper then determines vaguely sanely what you see through that window.

In practice that usually means that except for I/O (which is still terminally broken) you map the RAM over most of your address space, leave it as is and use the mapper.

Alan

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 13 Nov 2019 23:56:29 GMT View Forum Message <> Reply to Message jdgabbard wrote on Wed, 13 November 2019 12:49

Page 60 of 148 ---- Generated from RetroBrew Computers Forum Concerning compatibility with the PHC-23J and the NMS-8250, are any features lost when using one or the other?

The only reason I picked these machines, is that they seem to be good enough generic MSX2 systems with the slot configuration similar to Omega. PHC-23J BIOS configures VDP for NTSC video output (60 Hz refresh rate) and NMS-8250 BIOS configures VDP for PAL video output (50 Hz refresh). That's pretty much all the differences that I know of.

Quote: Specifically concerning the memory. My understanding of the MSX bios is that it automatically looks for memory in each slot/sub. However I see the the PCH doesn't have a mapper, while the NMS does have a 128k mapper. Any issue with reading the full range of memory with these BIOS's?

While it is possible that MSX2 BIOS automatically checks slots for memory/ROM extensions, it appears that it still expects to find RAM at the standard location. At least if I move RAM mapper to a different slot, MSX2 BIOS will no longer boot... C-BIOS actually auto-detects RAM location, and will boot as long as the RAM is available. As far as I know all MSX2 machines had a memory mapper. I actually haven't checked if these MSX2 ROMs detect the whole 512 KiB of memory... I should check that.

Quote: The reason I ask, is that while C-Bios is open source, it currently lacks 100% compatibility, and doesn't have cassette routines from what I read. So that would make the preferred BIOS of choice the NMS in my opinion.

C-BIOS functionality is pretty much limited to running software (games?!) from ROM cartridges. NMS is not the best option, since your TV is probably NTSC, also being originally a Japanese platform, most games expect 60 Hz refresh (and retrace interrupt), and will run somewhat slower on PAL system.

Quote: Second question, as I understand it, most mappers allow you to control each 16k page in a Slot. But from what I'm reading in your documentation it would appear that you mapped this to a single 64k page in slot 3-2. Is that correct? In MSX slots and memory pager are two different things ;-) It is a bit confusing, but basically, it works in three layers: Layer 1 & 2 - Primary and Expanded slots. There are 4 primary slots, each one can have an extended slot behind it. In case of Omega, only slot 3 is expanded. Although it is possible to install slot expanders in the external cartridge slots. Each slot can have 4 x 16 KiB memory blocks, starting at 0x0000, 0x4000, 0x8000, and 0xC000. The slot mechanism allows choosing which one of these memory blocks gets mapped to the CPU memory space. But it does not allow mapping these blocks at different addresses. For example, you can map slot 0 0x0000-0x3FFF to the CPU memory space 0x0000-0x3FFF. Now, the memory pager occupies an entire slot (3-2 in case of Omega), and it allows mapping any one of 16 KiB RAM pages to any one of these 4 memory blocks. RAM mapping looks something like this: [CPU]->[Slot 3]->[Sub-Slot 2]->[Memory Pager]->[SRAM]

Page 61 of 148 ---- Generated from RetroBrew Computers Forum Other than RAM memory pagers, there are also so called MegaROM cartridges. These are normally used for MSX2 games, that use 128 KiB (1 megabit) or bigger ROMs. In this case the mapper is usually somewhat simpler, and maps only two 16 KiB pages of ROM to the slot.

Hope this helps ;-) Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Thu, 14 Nov 2019 02:10:54 GMT View Forum Message <> Reply to Message Hehe... Alan beat me to it, and probably explained the MSX2 memory architecture a bit better ;-) But now you can compile both replies together, and get even more complete picture...

Subject: Re: MSX2 Compatible Computer Project Posted by etchedpixels on Thu, 14 Nov 2019 14:36:44 GMT View Forum Message <> Reply to Message The only other bits worth noting is that there are also MegaRAM boards that sort of work like the MegaROM and were used particularly in Brazil on MSX1 to get usable banked memory (and primarily to pirate cartridges...). It's also possible to add a mapper to an MSX1 machine, or a VDP9938 to an MSX1 machine or both, just to maximise confusion 8)

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Thu, 14 Nov 2019 15:27:10 GMT View Forum Message <> Reply to Message Sergey wrote on Wed, 13 November 2019 15:56 C-BIOS functionality is pretty much limited to running software (games?!) from ROM cartridges. NMS is not the best option, since your TV is probably NTSC, also being originally a Japanese platform, most games expect 60 Hz refresh (and retrace interrupt), and will run somewhat slower on PAL system.

I'm somewhat familiar with mappers and the IO/Addresses that they use. I do have an MSX1, along with a mega ram cart (SD-512). So I understand the gist of how they generally work. My question was more towards the specific hardware of the Omega, and the BIOS. Mostly whether it was capable of banking in the ram in 16k chunks, in the random order. Thanks for addressing that part. Now it seems that the question of whether those BIOS's recognize the entire memory area. Since one only has 64k of memory that it would normally see in that Sub, and the other has a Mapper capable of addressing the 128k. That is something I can't answer at the moment.

As for the above quote, it seems that NMS would still be the best option, though it would just

Page 62 of 148 ---- Generated from RetroBrew Computers Forum require a patch. Again, I'm not completely familiar with the MSX Bios, but my understanding is that it should come down to correcting a couple of values in ROM that are written to the registers. One would need to disassemble the bios into a listing and compare it with the available documentation to figure out which bytes to patch. But that may still be an option. My only other fear is that PHC-23J bios will not see the additional memory. Not all MSX2 computers had a mapper. And the PHC-23J is specifically one that DOES NOT, it only has a total of 64k of memory, according to the MSX.org page. So the question is, does the PHC-23J recognize the extra available memory. And if not, it may be useful to have a patched BIOS for the NMS, or potentially find another MSX2 bios that is comparable.

I'll take a look and see if I can track down another machine that may work.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Thu, 14 Nov 2019 15:38:29 GMT View Forum Message <> Reply to Message Regarding the PHC-23J, the one with the Yamaha S1985 as engine has a memory mapper. Not sure if the PHC-23J without memory mapper still has a BIOS with memory mapper code (I think it has).

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Thu, 14 Nov 2019 16:38:48 GMT View Forum Message <> Reply to Message lintweaker wrote on Thu, 14 November 2019 07:38Regarding the PHC-23J, the one with the Yamaha S1985 as engine has a memory mapper. Not sure if the PHC-23J without memory mapper still has a BIOS with memory mapper code (I think it has).

I stand corrected. It looks like the PHC-23J uses either the S1985 or the S3527, both of which have mappers according the the datasheets. So this is a non-issue. And looks like the PHC-23J BIOS should be a good fit.

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Fri, 15 Nov 2019 01:29:04 GMT View Forum Message <> Reply to Message jdgabbard wrote on Thu, 14 November 2019 08:38lintweaker wrote on Thu, 14 November 2019 07:38Regarding the PHC-23J, the one with the Yamaha S1985 as engine has a memory mapper. Not sure if the PHC-23J without memory mapper still has a BIOS with memory mapper code (I think it has).

I stand corrected. It looks like the PHC-23J uses either the S1985 or the S3527, both of which have mappers according the the datasheets. So this is a non-issue. And looks like the PHC-23J

Page 63 of 148 ---- Generated from RetroBrew Computers Forum BIOS should be a good fit. Glad this was resolved, but curiously when I was looking at the NMS-8250 page on the MSX wiki, I saw that it was a badge-engineered Sanyo Wavy25, which was an MSX2 with only 64k as well. The NMS (and a few other badge engineered models) got 128k.

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Fri, 15 Nov 2019 07:04:17 GMT View Forum Message <> Reply to Message Only for completeness: the S3527 does not have a mapper function (see datasheet, IO ports for the mapper are missing). It was more of a engine for MSX1.

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Fri, 15 Nov 2019 16:10:36 GMT View Forum Message <> Reply to Message lintweaker wrote on Thu, 14 November 2019 23:04Only for completeness: the S3527 does not have a mapper function (see datasheet, IO ports for the mapper are missing). It was more of a engine for MSX1.

Yeah, looks like you're right. The S3527 does have an expanded SLOT 3 (as well as SLOT 0), but it doesn't have a mapper to bank in the memory. I imagine the BIOS is still the same unless there was a revision. So it probably is still capable of detecting the memory on the Omega.

File Attachments 1) Capture.JPG, downloaded 1184 times

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Mon, 18 Nov 2019 16:29:14 GMT View Forum Message <> Reply to Message Sergey,

Any idea what type of power consumption this uses? I'm guessing it would be sub-2A. But that is just a guess.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 18 Nov 2019 19:48:24 GMT View Forum Message <> Reply to Message

Page 64 of 148 ---- Generated from RetroBrew Computers Forum Hi Doug,

If I recall correctly, I've measured about 750mA. So 5V / 2A power supply should be plenty. Note, that if you connect cartridges, they will consume some power too. Also note that with 5V power supply the board will not supply +12V / -12V voltages to cartridge slots. If you're planning to use cartridges that use 12V/-12V, you'll have to use a power supply that can provide all three voltages, and connect it to the connector J10.

Thanks, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Mon, 18 Nov 2019 21:01:04 GMT View Forum Message <> Reply to Message The reason I ask is, mentioned before, I plan on designing a case for this. And integrating a PSU is something I have in mind. I'm throwing together a small 12-5-/12 PSU design to connect through an IEC connector for testing. And just need to have an idea as the the current draw.

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Mon, 18 Nov 2019 21:34:14 GMT View Forum Message <> Reply to Message A 5v 2a psu is USB level power, that seems wrong. It's definitely easy to find a suitable supply but I don't know about anyone else, I can't solder a USB plug. Please don't make it more difficult than it needs to be, I can do the 5v power plug from the easyz80 i built, but frankly a 9 volt center negative would be ideal.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 18 Nov 2019 21:39:41 GMT View Forum Message <> Reply to Message There are two options for 5V/12V/-12V power supplies:

1. Power supply module that goes inside the case, for example Mean Well RT-50B (https://www.mouser.com/ProductDetail/709-RT50B) or Mean Well RT-65B (https://www.mouser.com/ProductDetail/709-RT65B). 2. Power brick and a cable to connect that power brick to the on-board 8-pin power connector. For example Mean Well GP25B13D-R1B (https://www.mouser.com/ProductDetail/709-GP25B13D-R1B) with 5 pin DIN panel mount connector (https://www.mouser.com/ProductDetail/161-0005-E). The DIN power connector can be soldered directly to the main board using short pieces of wire, or it is possible to make a short cable with 8-pin connector on the other end for more modular construction.

Page 65 of 148 ---- Generated from RetroBrew Computers Forum If you go with the second option, it might be possible to use the same case design for both 5V and 5V/12V/-12V options, with just a little modification for the power jack hole.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 18 Nov 2019 21:43:42 GMT View Forum Message <> Reply to Message bifo wrote on Mon, 18 November 2019 13:34A 5v 2a psu is USB level power, that seems wrong. It's definitely easy to find a suitable supply but I don't know about anyone else, I can't solder a USB plug. Please don't make it more difficult than it needs to be, I can do the 5v power plug from the easyz80 i built, but frankly a 9 volt center negative would be ideal. Omega uses the same 5V DC jack used in Easy Z80. 9V won't work, as the main board does not include voltage regulator (you must supply regulated 5V). USB chargers that supply 5V/2V should work just fine, given that a suitable USB Type A to DC barrel cable is used (e.g. https://www.amazon.com/Onite-5-5x2-1mm-Positive-Electronic-O rganorgan/dp/B01MZ0FWSK)

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Mon, 18 Nov 2019 22:02:16 GMT View Forum Message <> Reply to Message About this. I personally would prefer a box prepared to house a 3.5 "floppy disk drive before integrating the power supply.

Although I have no idea of the consumption in + 12v and -12v that MSX cartridges may need, you can take advantage of the circuit attached. This was among the old retrobrew files. It is an interface for MSX cartridges that is part of the N8VEM computer, which is powered only by 5v. This circuit contains some ICs that provide the required voltages.

To power the disk drive that I mention would require more power in that PSU. It would be necessary to review how the old MSX2 solved it. Well, I hope my find helps.

Jordi Solis File Attachments 1) Printing MSXCartReader-sch.pdf, downloaded 150 times

Page 66 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 18 Nov 2019 22:24:00 GMT View Forum Message <> Reply to Message jordi.solis wrote on Mon, 18 November 2019 14:02 To power the disk drive that I mention would require more power in that PSU. It would be necessary to review how the old MSX2 solved it.

3.5" drives only use 5V power supply. So unless you really need +12V/-12V, a powerful enough 5V supply will do. Thankfully the technology had advanced since mid-80's and fairly compact and inexpensive 5V/4A (and even 5V/6A) switching power supplies are now available.

Old MSX/MSX2 systems used linear power supplies with multiple secondary windings to produce the required voltages. Bulky, expensive, noisy, and inefficient...

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 18 Nov 2019 22:25:16 GMT View Forum Message <> Reply to Message Sergey wrote on Mon, 18 November 2019 14:24jordi.solis wrote on Mon, 18 November 2019 14:02 To power the disk drive that I mention would require more power in that PSU. It would be necessary to review how the old MSX2 solved it.

Old MSX/MSX2 systems used linear power supplies utilizing transformers with multiple secondary windings to produce the required voltages. Bulky, expensive, noisy, and inefficient...

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Mon, 18 Nov 2019 22:30:06 GMT View Forum Message <> Reply to Message ups! my answer was too late. I bet for the power brick.

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Tue, 19 Nov 2019 15:28:47 GMT View Forum Message <> Reply to Message

Page 67 of 148 ---- Generated from RetroBrew Computers Forum Sergey wrote on Mon, 18 November 2019 13:39There are two options for 5V/12V/-12V power supplies:

If you go with the second option, it might be possible to use the same case design for both 5V and 5V/12V/-12V options, with just a little modification for the power jack hole.

Both of those options are rather large to fit into a case and still have it aesthetically pleasing. I was thinking about something much smaller. Even the Pico-ATX PSUs that you can buy cheap on ebay for $10-20 are only 53x37mm, and provide 12v @ 8A, -12v @ 0.1A, 5v @ 8A (+1.5A Standby). Now granted you'd need a 12v Power Brick rated high enough to supply the Pico PSU. But realistically, that would likely only need to be in the area of 4 Amps. But this might also be a better solution to those who do not want to mess around with mains power.

I might go ahead and order one of these Pico PSUs to test with. I'm mostly concerned with how hot the PSU may get, as it doesn't have any mounting holes. Meaning I'd need to figure out how to secure it in the case. But being a switch mode supply I doubt it would be getting too hot. Either way, it seems like a valid solution, and I'm guessing has an integrated PS_On signal (I just looked at the manual, and verified this signal is present). Meaning that it may be as simple as using a Molex cable adapter and running the PS_On and a GND to the back of the case for a power switch.

Mind you, I'm still playing with this in my head, and it might be easy to just use a 12v Brick, with a small board to regulate a 5v supply, and a charge pump circuit to get the -12v reference. I'm just not sure how much current a cartridge that needs -12v would use.

Edited for update.

-Doug.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Tue, 19 Nov 2019 15:49:45 GMT View Forum Message <> Reply to Message Doug,

Maybe I wasn't clear on the second option. You don't need to fit the power supply in this case.

Page 68 of 148 ---- Generated from RetroBrew Computers Forum Just a DIN connector and a few wires.

Although, your idea with using a small board and 12V input voltage should work too. To get 5V from 12V it is possible to use a high efficiency DC-DC converter, e.g. https://www.mouser.com/ProductDetail/580-OKI78SR5-1.5W36C. For -12V, it might be possible to use LT1054 based charge pump converter. See the schematic Jordi shared above.

- SK

Subject: Re: MSX2 Compatible Computer Project Posted by andrii_kutepov on Sun, 24 Nov 2019 13:21:05 GMT View Forum Message <> Reply to Message Sergey,

As you know i collect part for Omega build. On githab i can read:

"V9958 VDP Support The Omega Main Baord can be configured to support either V9958 VDP (recommended) or V9938 VDP. To support V9958 VDP the board should be configured as follows:

Do not install the following components: Transistor: Q2 Capacitor: C43.."

Where C43 are Worth ?

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Sun, 24 Nov 2019 18:21:07 GMT View Forum Message <> Reply to Message C43 is a bypass capacitor for U43. If you'd like to have PAL support, you'll want to have U43 and C43. It doesn't hurt to have it installed anyway, even if you don't want to have PAL or V9938 support.

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Wed, 27 Nov 2019 04:56:27 GMT

Page 69 of 148 ---- Generated from RetroBrew Computers Forum View Forum Message <> Reply to Message Sergey,

I was going over the BOM, and noticed an error. For R27-33 you have listed 6 - 1k resistors. And at first, it didn't appear there was a R29, which would make the BOM correct. However, on v1.1 you do have an R29, which connects to pin 8 of U42 and VCC. That said, I'm assuming this is also a 1k value. But I didn't notice it mentioned on the BOM, or in any of the optional instructions. I'm thinking this just needs the BOM updated to note 7 - 1k resistors instead of the 6.

-Doug.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 27 Nov 2019 05:35:05 GMT View Forum Message <> Reply to Message jdgabbard wrote on Tue, 26 November 2019 20:56 I'm thinking this just needs the BOM updated to note 7 - 1k resistors instead of the 6.

Yes it should be 7 x 1k resistors. I've updated the Bill of Materials. Thank you for your feedback!

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Thu, 28 Nov 2019 15:58:15 GMT View Forum Message <> Reply to Message Sergey,

Another correction for you. Under the Mainboard Building Instructions document, in the Optional Components Section, you state "8087 math co-processor U1 is completely optional". I'm assuming this is a remnant from using the Xi-8088 version as a template.

-Doug.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Thu, 28 Nov 2019 16:59:55 GMT View Forum Message <> Reply to Message Doug,

Thanks again. That document is kind of work in progress. It is very likely it will contain a lot of errors. I removed that reference to 8087 and some other non-relevant stuff. I need to find time to edit in the actually

Page 70 of 148 ---- Generated from RetroBrew Computers Forum relevant content.

- SK

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Mon, 02 Dec 2019 10:41:14 GMT View Forum Message <> Reply to Message Hi guys, I have some Obsonet 1.0 bare boards available, this will let you build an MSX network card with developed drivers for MSX-DOS and NEXTOR. you can see all the projetct details here: http://obsonet.blogspot.com/ If you like I can send you one board at 5$ + shipment. Let me know Jordi Solis

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 04 Dec 2019 19:08:49 GMT View Forum Message <> Reply to Message Speaking about MSX hardware expansion, Xavirompe was kind enough to send me his Rookie Drive NX. I've tested it with Omega and it works perfectly :) I guess that resolves "we need an FDC interface" issue ;-)

- SK

File Attachments 1) Omega_with_Rookie_Drive_NX.jpg, downloaded 876 times

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Wed, 04 Dec 2019 22:12:14 GMT View Forum Message <> Reply to Message hi Sergey, all I saw that U15-18 are 74HC on the bom but 74HCT on the silkscreen. So I looked for its differences on the internet. It seems like they are equivalents, but even better 74HCT are level compatible with 74LS. I'm getting hard to find some of them specially AHCT, so... Could I just mix hct with LS or replace the AHCT by 74F or 74ALS? I don't think you were specified most of them as HCT but some as 74F if that wasn't a matter.

Page 71 of 148 ---- Generated from RetroBrew Computers Forum Just consider include this (HC vs HCT) as an issue. J. S.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 04 Dec 2019 22:32:57 GMT View Forum Message <> Reply to Message Jordi,

It shouldn't be any issues with using 74HC670 as long as the other ICs you're using are CMOS. Particularly Z84C00 CPU and U37 74AHCT32. The reason I mention 74HC670 in the BOM is that it is four times cheaper than 74HCT670 at Mouser ($1.69 vs. $6.90). I have no idea why a simple CMOS logic IC would cost that much... Omega uses a fairly low clock, so you can use 74HCT instead of 74AHCT. Low power TTL ICs (74ALS, 74F) should work too. Just do not mix them together with 74HC parts. Also if you're installing U43 (e.g. for PAL clock), it must be a CMOS part. Even 74LS should do... but if you use them throughout the board the power consumption will go up. The MSX standard specifies that the MSX cartridge interface should use TTL levels, and that is the reason for using 74F there. I presume 74HCT would work just as well...

Thanks, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Sun, 08 Dec 2019 15:19:11 GMT View Forum Message <> Reply to Message hi Sergey, in your documentation about NTSC: Do not install the following components (they are required for PAL support only):

Crystal Oscillator: Y3 Capacitors: C43, C90, C93 Resistors: R1, R3; Integrated Circuit: U43 Note: C43 and U43 also used for V9938 VDP CSYNC level converer. They must be installed if V9938 VDP is used

Is there possible you mean R30 and not R3? Another question, I would like to test NTSC and PAL. Is actually needed to plug those components out? let me know. regards.

Page 72 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Tue, 10 Dec 2019 00:41:01 GMT View Forum Message <> Reply to Message jordi.solis wrote on Sun, 08 December 2019 07:19 Is there possible you mean R30 and not R3?

You're absolutely correct. I'll fix the documentation. jordi.solis wrote on Sun, 08 December 2019 07:19 Another question, I would like to test NTSC and PAL. Is actually needed to plug those components out? let me know.

You can keep these components for NTSC. Just move the JP5 and JP6 jumpers. Although, for a longer term use, if you decide to stay with NTSC (and you're not using V9938 VDP), I would recommend to remove U43, so that it doesn't generate extra noise.

Note that the recommended values of R9 and C91 differ between NTSC and PAL. With that being said NTSC values worked for me with PAL frequencies, but perhaps I'd get better video quality when using the recommended PAL values (I haven't tested that).

Thanks, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Fri, 13 Dec 2019 20:35:02 GMT View Forum Message <> Reply to Message Hi guys, I build some MSX-Pi bare boards. this will let you access OS on SD card, wifi internet access. Includes MSX-DOS and NEXTOR disk images and is compatible with all MSX versions (even MSX1 througt BASIC CALL instructions). You can see all the projetct details here: https://github.com/costarc/MSXPi I also have some prototype cartridge spare boards. https://github.com/Wierzbowsky/MSX_Breadboard_Large If someone likes it just send me $10 by board (+shipment). Let me know Jordi Solis

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Sun, 15 Dec 2019 10:51:26 GMT View Forum Message <> Reply to Message Hi sergey,

Page 73 of 148 ---- Generated from RetroBrew Computers Forum I got an error message trying to burn the BIOS, like the size on the omega_msx2_ntsc.bin and memory size doesn't fit.

$ minipro -p SST39SF040 -w omega_msx2_ntsc.bin -c code -e Found TL866II+ 04.2.109 (0x26d) Chip ID OK: 0xBFB7 Incorrect file size: 475136 (needed 524288)

Question: I'm using the V9958 chip, shouldn't I burn an MSX2+ BIOS?

If someone can help me. I would also try replacing the needed files to get a commercial version of the bios. Thank you for giving me support. Jordi Solis.

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Sun, 15 Dec 2019 19:42:02 GMT View Forum Message <> Reply to Message Are these keys compatible with the keyboard PCB pin placements? They don't appear to be from the PCB layout but there are no pictures of the unpopulated board.

https://www.ebay.com/itm/Mechanical-Switch-Keyboard-Blue-Bro wn-Black-Red-Replacement-for-Cherry-MX-Ki-RAC/153590352132?s sPageName=STRK%3AMEBIDX%3AIT&var=453610981985&_trksi d=p2060353.m2749.l2649

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 16 Dec 2019 03:02:15 GMT View Forum Message <> Reply to Message jordi.solis wrote on Sun, 15 December 2019 02:51 I got an error message trying to burn the BIOS, like the size on the omega_msx2_ntsc.bin and memory size doesn't fit.

$ minipro -p SST39SF040 -w omega_msx2_ntsc.bin -c code -e Found TL866II+ 04.2.109 (0x26d) Chip ID OK: 0xBFB7 Incorrect file size: 475136 (needed 524288)

It appears that you're missing some of the input ROM images. Check the make_rom.sh script for the ROM file names and locations. Also check its output for errors. jordi.solis wrote on Sun, 15 December 2019 02:51 Question: I'm using the V9958 chip, shouldn't I burn an MSX2+ BIOS?

V9958 works perfectly with MSX2 BIOS. Omega might work with MSX2+ C-BIOS, but I haven't

Page 74 of 148 ---- Generated from RetroBrew Computers Forum tested it yet.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 16 Dec 2019 03:12:17 GMT View Forum Message <> Reply to Message bifo wrote on Sun, 15 December 2019 11:42Are these keys compatible with the keyboard PCB pin placements? They don't appear to be from the PCB layout but there are no pictures of the unpopulated board.

https://www.ebay.com/itm/Mechanical-Switch-Keyboard-Blue-Bro wn-Black-Red-Replacement-for-Cherry-MX-Ki-RAC/153590352132?s sPageName=STRK%3AMEBIDX%3AIT&var=453610981985&_trksi d=p2060353.m2749.l2649 They do look similar to the original Cherry MX switches. But obviously I can't guarantee that they have exactly the same footprint.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Tue, 17 Dec 2019 20:06:25 GMT View Forum Message <> Reply to Message For the folks building the Omega Home Computer, I've added some troubleshooting tips here

Please do not be shy to ask any questions. The system might be a bit tricky to debug, since it doesn't really provide any indication of system activity until it actually boots up :)

My general advice is to use C-BIOS (instead of MSX2 BIOS) for initial power-on and debugging. C-BIOS will boot even with non-functioning RAM and RTC, while MSX2 BIOS won't.

- Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Wed, 18 Dec 2019 16:17:53 GMT View Forum Message <> Reply to Message Sergey, Thank you for your support, it has helped me a lot. As I told you I had problems finding inductances of that type and installed another encapsulation. As it did not fit properly, a weld was not well connected. Also I had not installed the battery. Finally it works. Unfortunately, the MSXPi cartridge does not work with OMEGA. It works well with ARTEMISA (MSX1) but not with OMEGA. (It is tested with other commercial MSX2). It may be a problem on my card, I will continue testing.

Page 75 of 148 ---- Generated from RetroBrew Computers Forum Thanks again. Jordi Solis

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 18 Dec 2019 17:04:59 GMT View Forum Message <> Reply to Message Hi Jordi,

I am happy to hear that you've got your Omega to work! jordi.solis wrote on Wed, 18 December 2019 08:17 Unfortunately, the MSXPi cartridge does not work with OMEGA. It works well with ARTEMISA (MSX1) but not with OMEGA. (It is tested with other commercial MSX2).

It would be interesting to test it with other cartridges. My system works with all the cartridges I've tried so far. The only issue I had is C-BIOS rebooting with Metal Gear cartridge. MSX2 BIOS works fine with it though...

- Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Thu, 02 Jan 2020 18:58:31 GMT View Forum Message <> Reply to Message bifo wrote on Sun, 15 December 2019 11:42Are these keys compatible with the keyboard PCB pin placements? They don't appear to be from the PCB layout but there are no pictures of the unpopulated board.

https://www.ebay.com/itm/Mechanical-Switch-Keyboard-Blue-Bro wn-Black-Red-Replacement-for-Cherry-MX-Ki-RAC/153590352132?s sPageName=STRK%3AMEBIDX%3AIT&var=453610981985&_trksi d=p2060353.m2749.l2649 Update on this, I received my Omega boards today and they do fit. Total cost for 80 switches ran me about $14.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Fri, 10 Jan 2020 16:39:44 GMT View Forum Message <> Reply to Message Hi, I would like to use better versions of ROMBIOS and BASIC. Even for msx2 there are several updates for BASIC 2.x that we could try. On the other hand I have tried some MSX2 + game that has worked, so I think there is already partial compatibility and could be expanded by updating the bios.

Page 76 of 148 ---- Generated from RetroBrew Computers Forum I found a page showing how to update a Phillips NMS 8245, which is a model very similar to the NMS 8250 (or so I think). I hope someone helps me update the current omega bios. This is the page mentioned: https://www.msxinfo.net/tag/plus/

I failed to get PAL video for SCART and I will retest via RGB to SCART. Is it expected that the video quality will be better when connected by RGB?

Greetings.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Fri, 10 Jan 2020 19:45:02 GMT View Forum Message <> Reply to Message jordi.solis wrote on Fri, 10 January 2020 08:39 I think there is already partial compatibility and could be expanded by updating the bios. I found a page showing how to update a Phillips NMS 8245, which is a model very similar to the NMS 8250 (or so I think). I hope someone helps me update the current omega bios. This is the page mentioned: https://www.msxinfo.net/tag/plus/

Of course all the V9958 VDP stuff described on the page is irrelevant, since it is possible to install V9958 directly in Omega. I think the easiest route would be grabbing an existing MSX2+ BIOS, and trying to run it on Omega. There are several possible issues with such approach: 1. All MSX2+ machines have memory (RAM) mapper in Slot 3-0, Omega has it in slot 3-2. It should be possible to slightly modify U13 SPLD code to change the mapping. 2. MSX2+ machines have 0xF4 I/O port, one of the purposes is to indicate hard or soft reset. I am not exactly sure what MSX2+ BIOS would do if it can't read back this port. It might be possible to patch the BIOS to ignore it :) 3. MSX2+ normally have MSX-MUSIC (OPLL), it is not a part of the MSX2+ standard, but perhaps the lack of it will confuse the BIOS.

For starters we can try MSX2+ C-BIOS, it shouldn't be sensitive for any of the issues above

Quote: I failed to get PAL video for SCART and I will retest via RGB to SCART. Is it expected that the video quality will be better when connected by RGB?

Yes, I'd expect a better video quality using SCART/RGB. I don't have a TV set with SCART, so I can't really test. But, I've tested PAL timing (note, it requires PAL-specific MSX BIOS), and obviously RGB signals are properly produced, otherwise CXA1645 wouldn't work.

Page 77 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Fri, 10 Jan 2020 20:40:48 GMT View Forum Message <> Reply to Message I've updated the schematic and the PCBs for both the keyboard and the main board. Updates are: - Keyboard now uses a SIP-6 resistor array instead of SIP-10. Basically, with the previous version some keyboard column signals had two pull-up resistors (one on the keyboard PCB another one on the main board, now they have only one each. - Main board - fixed a resistor and inductors' values on the silk screen I've reordered the PCBs, and I have some on hands if someone would like to purchase them.

Thanks, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Sat, 11 Jan 2020 07:09:32 GMT View Forum Message <> Reply to Message Wrt MSX2+ BIOS: - you should be able to 'build' a ROM set for MSX2+ without MSX-MUSIC ROM. Works just fine - MSX2+ without the 0xf4 IO port, depending on the BIOS version, it will either never show the MSX2+ bootscreen (soft reset) or it will always show it (hard reset). This depends on the presents or absence of 'CPL' Z80 instruction in that routine in the BIOS - Memory in slot 3-2: MSX BIOS code will search for RAM on bootup. My guess is it will find it (as it will also find RAM in cartridges and other subslots)

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Mon, 13 Jan 2020 16:14:47 GMT View Forum Message <> Reply to Message Sergey,

I think these cartridge connectors are a little more correct. They're pretty expensive through Mouser, but about the same price as the ones you list on the BOM through Digikey.

https://www.digikey.com/products/en?keywords=395-050-520-202 %E2%80%8E

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Wed, 12 Feb 2020 23:11:17 GMT View Forum Message <> Reply to Message Hi, I have a technical question.

Page 78 of 148 ---- Generated from RetroBrew Computers Forum I would like to build a simple font for Omega MSX similar to a pc source. I would like to mount an elegant system similar to a peak-psu but of less power. The problem is that I don't locate a complete scheme. It occurs to me that it should be easy to build a pico-psu source by fitting several step-down or step-up modules. Can anybody help me? regards.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 12 Feb 2020 23:32:03 GMT View Forum Message <> Reply to Message Hi Jordi,

You have two options to go about it: 1. Build your own DC-DC converter. There are a few IC controllers for DC-DC converters, e.g. MC34063. This is fairly old IC, and there are newer and better ones in existence now. You'll also need a couple of inductors, diodes, and a few capacitors and resistors. 2. Use a ready-made DC-DC converter module. You don't need a lot of power, even a +/-40mA converter should be enough. Martin Lukasek had designed a PCB to use with TRACO Power TDR 3-0522 module: https://oshpark.com/shared_projects/RI2qnxel Check the availability of DC-DC converters first. I couldn't find this one at Mouser :)

Thanks, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Fri, 14 Feb 2020 18:36:30 GMT View Forum Message <> Reply to Message Hi, thanks. I finally found what I didn't know but existed. A buck boost positive-negative module. so, with just one module like this https:// es.aliexpress.com/item/32789671683.html?spm=a2g0s.9042311.0. 0.157963c01IXSVJ, I think it would be enough.

You may be interested to know this information about energy consumption in the MSX. 1.5.4 Cartridge Power Capacity +5v 300mA/Slot +12v 50mA -12v 50mA

Page 79 of 148 ---- Generated from RetroBrew Computers Forum regards.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Fri, 14 Feb 2020 18:47:40 GMT View Forum Message <> Reply to Message Hi Jordi,

I've ordered this one from Mouser: https://www.mouser.com/ProductDetail/495-TBA2-0522 It looks that it should work just fine, it supplies 80mA on +/-12 V outputs. I'll give it a try during the weekend and report back.

Cheers, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by b1ackmai1er on Mon, 17 Feb 2020 10:14:19 GMT View Forum Message <> Reply to Message Great to see some photo's, more please :)

I didnt realize to keyboard sat on top :)

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Mon, 17 Feb 2020 11:38:20 GMT View Forum Message <> Reply to Message sorry, please share more pictures.

PD: Did you build an Omega Phillip?

Subject: Re: MSX2 Compatible Computer Project Posted by martin8bity on Fri, 06 Mar 2020 09:36:05 GMT View Forum Message <> Reply to Message I created small module

http://www.8bity.cz/2020/power-module-12v-for-omega-home-com puter

Page 80 of 148 ---- Generated from RetroBrew Computers Forum based on TRACO POWER TDR 3-0522 (Mouser 495-TDR3-0522). It is a bit expensive, but with sufficient power and fits perfect to the available space.

Eagle sources attached, shared project with Gerber is on OSHPARK https://oshpark.com/shared_projects/RI2qnxel.

File Attachments 1) Omega_DCDC12V_in-Omega-front-top-left.jpg, downloaded 1724 times 2) Omega_DCDC12V_top.jpg, downloaded 122 times 3) Omega_DCDC12V_in-Omega-back.jpg, downloaded 115 times 4) Omega_DCDC12V_in-Omega-side.jpg, downloaded 108 times 5) Omega_PSU_Lite.zip, downloaded 122 times

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Fri, 06 Mar 2020 10:08:24 GMT View Forum Message <> Reply to Message Nicely done!

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Fri, 06 Mar 2020 12:43:49 GMT View Forum Message <> Reply to Message Martin, What a nice job! I was working on the same way, however I'm always looking for a cheaper solution. My solutions are still prototype, not so professional as yours. I shared them on Instagram, sorry for wont be sharing them here before. Here you are some linked pictures. https:// www.instagram.com/p/B9ZHctKIOHN/?utm_source=ig_web_copy_link https:// www.instagram.com/p/B9ZHKDAIefm/?utm_source=ig_web_copy_link

It looks like I don't have permissions to upload pictures to this forum.

Kind regards.

Page 81 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by borutk on Sat, 07 Mar 2020 19:57:09 GMT View Forum Message <> Reply to Message Hi,

I have built an Omega with a version 1.1 PCB. It's not functioning properly, so i have some questions if anyone has some ideas what could be wrong. It works with CBIOS, but not with other MSX2 bios. I guess my RTC arrived crappy from ebay and i have ordered a new one. Even with the CBIOS it doesn't work with any of the couple of cartridges that i have. Cartridges seem to be ok, they work in a Toshiba MX-10 and they are both simple 32k rom carts. But the worst is that it will randomly destroy RAM, it might work for a while but on next switch on the screen is blank and when i test the RAM it's faulty. Any ideas why? Also, what should i change to use 128K RAMs instead of 512K? I am waiting on a new set of RAMs but 128K RAM is much cheaper until i find the problem. And last question, would it be possible to use MSX1 CBIOS or does the system require MSX2?

Best regards, bo/

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Sat, 07 Mar 2020 20:06:28 GMT View Forum Message <> Reply to Message Hi Borutk Is there possible that from the beginning RAM chip was wrong? If works with C-BIOS problem must be on RTC chip or RAM chip. Maybe your RAM chip was randomly destroyed before you get it. There's any warm chip (I mean actually hot). Do you have any other AS6C4008 to replace it? What if you insert the RTC but not the RAM, Then you have any difference with C-BIOS?

Regards. Jordi Solis MsxMakers

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Sat, 07 Mar 2020 20:12:45 GMT View Forum Message <> Reply to Message Additionally, 1) To try with another kind of RAM chip, check they have the same connections on datasheet, I don't think this could be possible with a low capacity chip. I think you would only use a 128K chip

Page 82 of 148 ---- Generated from RetroBrew Computers Forum with a board adaptor or some wire connections. 2) of course you need a MSX2 or 2+ CBIOS to work with Omega, sorry, mainly they have different video chips or RAM distribution. regards Jordi Solis MsxMakers

Subject: Re: MSX2 Compatible Computer Project Posted by borutk on Sat, 07 Mar 2020 20:57:06 GMT View Forum Message <> Reply to Message RAM was good from the start, at the moment i am at my third AS6c4008, they were first tested with TL866 eprom programmer which has RAM test mode. Then they for a while worked in Omega, and finally they stopped. Also i found out by trial and error that Omega is a bit finicky with 8255, i have a few 8255s which work fine as PPI-IDE in Sergey's Zeta but don't work in an Omega. With this 8255s i get the ERROR: MEMORY NOT FOUND message from CBIOS. The difference between 512K RAM and 128K ram is that pin1 (A18) is NC and pin30 (A17) is CE, so it has to be 1. But if CBIOS scans the whole memory space, it should find a contiguous block of 128K which should be enough for it to work. I'll try bending pin 30 and connecting it to Vcc tomorrow.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Sat, 07 Mar 2020 21:38:19 GMT View Forum Message <> Reply to Message Hi, If at first they worked but they stopped doing it, three times, I would not try another chip until locate the fault. Check all the tracks on that chip until you find a scratch, a cold weld or something making contact between its pins. If you can't find it, try turning it on without that chip and observe its pins with an oscilloscope. Check that no chip heats up, and all voltage levels. If your power supply has +12 and -12 try connecting only + 5v Check for anything inside the slot connectors, clean it with a brush. If you have a cooling spray, spray on the circuit and power on to locate something with an abnormal temperature. It is also possible that after checking the circuit you have a CI in an inverted position or with one of its bent pin. Without further testing, I would not insert another memory chip, which has broken a third chip, breaks a fourth. You can also replace all the chips you have with others, eliminate all that are optional, or change positions that are the same to find any changes. Nothing changes if you don't change anything.

Page 83 of 148 ---- Generated from RetroBrew Computers Forum To have a different result, try a different source.

I hope this helps. J S

Subject: Re: MSX2 Compatible Computer Project Posted by martin8bity on Sun, 08 Mar 2020 09:50:05 GMT View Forum Message <> Reply to Message Faulty RTC causes MSX2 BIOS to stuck at black screen. CBIOS works OK. I had also faulty RTC from eBay and the symptom was stucked MSX2 BIOS, while CBIOS and cartridge games working OK.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Sun, 08 Mar 2020 19:16:42 GMT View Forum Message <> Reply to Message Hi Borut,

What type/manufacturer of the 8255 you are using? I've been using Intersil CP82C55A, and I am wondering if using an older NMOS part would create any issue... It shouldn't. It only used to control the keyboard and primary slot selection. Both are not time-sensitive and either one should work fine if you are using 74HCT/74AHCT/74LS logic. There potentially might be an issue if you're using NMOS 8255A with 74HC or 74AHC logic. The computer should not destroy SRAMs... I personally suspect power supply issue. Try using a different power supply 5V 3A or so. I recommend against using cheap USB chargers. They don't filter the output...

128K or 512K should work fine with the modifications you've mentioned. I don't think MSX1 BIOS will boot. The VDP initialization is a bit different, and, possibly MSX1 will not work with paged memory (C-BIOS actually might support that). What is the reason for using the MSX1 BIOS? Cartridges - again, if you're are using 74HC or 74AHC for the buffers/transceivers, that might cause issues, especially if the cartridge uses older NMOS ROM or TTL logic.

Thanks, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by jcoffman on Sun, 08 Mar 2020 19:43:18 GMT View Forum Message <> Reply to Message The NEC 71055 is a compatible chip to the 82C55A. I have used them several times.

Page 84 of 148 ---- Generated from RetroBrew Computers Forum --John

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Mon, 09 Mar 2020 16:17:37 GMT View Forum Message <> Reply to Message [quote] I don't think MSX1 BIOS will boot. The VDP initialization is a bit different, and, possibly MSX1 will not work with paged memory (C-BIOS actually might support that). What is the reason for using the MSX1 BIOS? /quote]

The MSX1 BIOS works just fine with the MSX2/2+ VDP. I does not however initialize the memory mapper. A small patch to the BIOS will fix that (I needed I have such version ready).

Subject: Re: MSX2 Compatible Computer Project Posted by tangent on Mon, 16 Mar 2020 18:23:09 GMT View Forum Message <> Reply to Message I had a great time building this!

I used the parts on the BoM, but had to separately acquire a "6.5u" Cherry stabilizer bar for the space bar. It's running well enough with the Sanyo MSX2 BIOS configured as NTSC with a V9958, but cartridge compatibility is a bit spotty. I tried replacing the U15-U18 74HC670's with HCT's but unfortunately didn't notice much of an improvement, at least on these carts:

Nemesis: Boot loop to green screen. This one surprised me - can anyone verify function of this common cart on their system? Warroid: Green screen Bosconian HAL Hole in One

Most of my utility cartridges are working, so I am able to load these games to MegaFlashROM and play them if I want, but I'm curious if there is anything else I can try to improve compatibility. :)

Edit: This was fixed by Jordi's fix for the Slot Direction SPLD! Thanks Jordi!

Subject: Re: MSX2 Compatible Computer Project Posted by borutk on Mon, 16 Mar 2020 18:54:46 GMT View Forum Message <> Reply to Message Hi guys,

Page 85 of 148 ---- Generated from RetroBrew Computers Forum It seems Sergey was right, the power supply gives a nasty spike at start up and then settles to 5V. It actually isn't a cheap wall wart, we use these supplies at work, but modern SoCs don't use 5V so there is at least one more regulator on board. At the moment i still use the same supply, but i connect it to the board after switching it on, and it seems to work, but i'll have to replace it with a new one. After replacing the RTC both BIOSes work most of the time, i suspect there is a bad connection somewhere because booting would sometimes fail.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 16 Mar 2020 19:01:08 GMT View Forum Message <> Reply to Message Hi Nicholas,

Thanks for sharing the photo of your build! I like the keycaps, they look very 80's :)

The type of 74HC670's shouldn't matter, as long as your CPU and U37 (74HCT32) are CMOS. They don't have much to do with cartridge's operation anyhow.

I don't have these particular cartridges, I do have Metal Gear, Vampire Killer, USAS, and Aleste, and all are working fine. The only issue I observe is with Metal Gear and C-BIOS, for whatever reason this combination, makes Omega reboot. But it works just fine with MSX2 BIOS.

I am wondering if any of these cartridges require +/-12V? Another simple thing to try is replacing the power supply, check if you have 5V/3A or so power supply around that you can use.

Cheers, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Mon, 16 Mar 2020 22:36:13 GMT View Forum Message <> Reply to Message Hi everyone, I have another problem. When I use the NTSC configuration I can connect a composite video TV to SCART or super video to SCART. The video signal is not perfect but you can see something on the screen. I can also connect DIN-8 to scart and then the signal is wonderful. On the other hand, if I configure the board in PAL mode, I can only get a video signal using the DIN-8 connector because with the other connectors I don't receive a video signal. Also, for some reason, some games (or all) cannot be loaded with PAL settings (or perhaps I would say with PAL BIOS). For example Galaga restarts constantly, while with NTSC it always works).

Page 86 of 148 ---- Generated from RetroBrew Computers Forum Does it make sense not to get PAL composite video signal through SCART? Finally, the best thing about the PAL BIOS is to have a keyboard configuration that matches the

I will try to make an msx2 + BIOS with PAL character map.

Kind regards. Jordi Solis.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 16 Mar 2020 23:59:24 GMT View Forum Message <> Reply to Message jordi.solis wrote on Mon, 16 March 2020 15:36Hi everyone, I have another problem. When I use the NTSC configuration I can connect a composite video TV to SCART or super video to SCART. The video signal is not perfect but you can see something on the screen. I can also connect DIN-8 to scart and then the signal is wonderful. On the other hand, if I configure the board in PAL mode, I can only get a video signal using the DIN-8 connector because with the other connectors I don't receive a video signal.

DIN-8/SCART uses Composite for sync, so if Composite doesn't work, RGB will not work either. I suspect something if wrong with the SCART adapter (I suspect you are using one to connect S-Video or Composite to your TV). Can you try using a different input on the TV (e.g. use RCA connectors, or S-Video instead of SCART with an adapter), or a different monitor / TV?

With that being said, I've tested S-Video and Composite in both PAL and NTSC modes. I don't have an RGB/SCART input, so I haven't tested that. By the way, if you switch between NTSC and PAL, CXA1645 would need slightly different values of R9 and C91. PAL worked for me with NTSC component values, but the video quality wasn't that great.

Quote: Also, for some reason, some games (or all) cannot be loaded with PAL settings (or perhaps I would say with PAL BIOS). For example Galaga restarts constantly, while with NTSC it always works).

Games are normally written for either NTSC or PAL, but not both. That is because the periodic interrupt frequency is different (60 Hz vs. 50 Hz), and games commonly use this interrupt for timing. I don't think it would make a program or a game fail, but the timing might be off, e.g. the game will feel "slower".

Quote: Finally, the best thing about the PAL BIOS is to have a keyboard configuration that matches the

I will try to make an msx2 + BIOS with PAL character map.

Not 100% sure, but perhaps just change the value of bits 0-3 at address #002C in the BIOS

Page 87 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by tangent on Tue, 17 Mar 2020 19:54:20 GMT View Forum Message <> Reply to Message Sergey wrote on Mon, 16 March 2020 12:01I am wondering if any of these cartridges require +/-12V? Another simple thing to try is replacing the power supply, check if you have 5V/3A or so power supply around that you can use. Unfortunately I didn't notice an improvement using a 5V/3A power supply. I think the only cartridge I have which requires +/-12V is an ASCII MSX-Serial 232 which seems to be working perfectly. :)

the character map is located, I will try to make an msx2 + BIOS with PAL character map. I'd be very interested in this!

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Wed, 18 Mar 2020 06:44:43 GMT View Forum Message <> Reply to Message tangent wrote on Tue, 17 March 2020 20:54Sergey wrote on Mon, 16 March 2020 12:01I am wondering if any of these cartridges require +/-12V? Another simple thing to try is replacing the power supply, check if you have 5V/3A or so power supply around that you can use. Unfortunately I didn't notice an improvement using a 5V/3A power supply. I think the only cartridge I have which requires +/-12V is an ASCII MSX-Serial 232 which seems to be working perfectly. :)

the character map is located, I will try to make an msx2 + BIOS with PAL character map. I'd be very interested in this! There is no such thing as a 'PAL' character map :p . Unfortunately the supported character map is hard baked into the BIOS so changing the language bits does not help. Potential keyboard layouts: KEYTYP keyboard layout 0 = Japanese 1 = International (QWERTY/other) 2 = French (AZERTY) 3 = English 4 = German (DIN) 5 = USSR 6 = Spanish 7 = Swedish ??

What version do you need? Most variants are available on the net.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Wed, 18 Mar 2020 17:32:10 GMT

Page 88 of 148 ---- Generated from RetroBrew Computers Forum View Forum Message <> Reply to Message Hi Guys, Maybe the default chartset map differs from NTSC to PAL BIOS What refers to my preferences, the only thing that I want is fitting the current omega keyboard with it's keycaps, let me explain: with the NTSC BIOS version, when I push on 2@ key I obtain the number 2 or " simbol, but with the PAL version of the BIOS all keycaps fit with their symbols. So that, I will try with international or english, and if I get an spanish set of keycaps maybe that. kind regards.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Wed, 18 Mar 2020 18:55:22 GMT View Forum Message <> Reply to Message Hi Sergey,

If bit 0-3 on byte #002C sets the keyboard language... What does it do the JP2 jumper?

Let me know

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 18 Mar 2020 18:59:08 GMT View Forum Message <> Reply to Message jordi.solis wrote on Wed, 18 March 2020 11:55If bit 0-3 on byte #002C sets the keyboard language... What does it do the JP2 jumper?

It selects the Japanese keyboard type/layout. It is MSX specs, so I thought I should implement that. Probably it is useless for European/US layouts :)

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Fri, 20 Mar 2020 15:18:50 GMT View Forum Message <> Reply to Message Hi Guys, thanks for helping me

I tried changing the contents of 2c memory and that is what I fount: both, MSX2 and MSX2+ NTSC BIOS had 00 on that memory location (corresponding to Japanese?) and this does not match with my keyboard at all, MSX2 PAL BIOS had 11 on that memory possition (what would mean qwerty international) and this works pretty good to me. the better I would dream would be Spanish layout working but I'm not sure if possible without

Page 89 of 148 ---- Generated from RetroBrew Computers Forum rebuilding the entire keyboard PCB because the shape of some keys (like ENTER key) are different but I would like to try and found what can and cannot be done.

So, I tested changing this byte on my BIOS but nothing happened. Neither with Japanese jumper.

"There is no such thing as a 'PAL' character map Razz . Unfortunately the supported character map is hard baked into the BIOS so changing the language bits does not help." That makes sense to my tests.

"What version do you need? Most variants are available on the net."

I would be happy if someone helpme to have any of those versions, international, Spanish and maybe some other like English.

Kind regards.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Fri, 20 Mar 2020 17:25:02 GMT View Forum Message <> Reply to Message Hi Jordi,

You can try using an MSX2 BIOS from an MSX2 machine of your choice on Omega. Preferably, the slot mapping should match that of Omega. But if needed, it is possible to modify the expanded slot mapping by reprogramming the respective SPLD. If in doubt you can test the BIOS in OpenMSX using a custom machine configuration.

Thanks, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Sat, 21 Mar 2020 11:58:05 GMT View Forum Message <> Reply to Message Hi, With this link you should be able to find 'systemroms.zip' which holds the roms for a lot of MSX machines. http://www.msxarchive.nl/pub/msx/emulator/openMSX/

Wrt slot order, I have found that the MSX(2/2+) BIOS is not that picky where it subroms are. It just looks from roms with start with 43h, 44h (normal program ROMs use 41/42h). On my homemade MSX (Z8TY) I have expanded slot 0 and most ROMS live in a slot 0 subslot, works just fine.

Page 90 of 148 ---- Generated from RetroBrew Computers Forum I think the same goes for RAM, it should not matter in what slot the RAM lives (maybe RAM in slot 0 subslots would not work). (otherwise e.g. RAM cartridges would not work)

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Sat, 21 Mar 2020 21:37:58 GMT View Forum Message <> Reply to Message lintweaker wrote on Sat, 21 March 2020 04:58Hi, With this link you should be able to find 'systemroms.zip' which holds the roms for a lot of MSX machines. http://www.msxarchive.nl/pub/msx/emulator/openMSX/

I think the same goes for RAM, it should not matter in what slot the RAM lives (maybe RAM in slot 0 subslots would not work). (otherwise e.g. RAM cartridges would not work) the problem isn't going to be 'can we make the thing function' it's going to be 'can we build a machine that msx hardware sees as being msx. my project slowed down because i purchased an old korean MSX2, 128k/128k, and it works fine for me to test software on. the memory structure is completely different. the MSX standard was brilliant in the time. that being said, the question is how flexible is the standard when we're bodging together a computer designed by a brilliant nerd on his down time. i mean, when wozniak was selling kits for the apple 1, how many were successfully built into machines you'd pay $10k for

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Sun, 22 Mar 2020 05:50:12 GMT View Forum Message <> Reply to Message Hi,

So I figured why MSX2+ BIOS was not booting with the logo... It was a rather silly mistake in the Slot Select SPLD (omega-slot_select.pld). Initially I programmed the SPLD so that only 16 KiB of Flash ROM are mapped to slot 3-0 0x0000-0x3FFF. Obviously, MSX2+ uses Kanji BASIC ROM to show the boot splash screen. It is located in slot 3-0 0x4000-0xBFFF. I did modify the SPLD to map that area to Flash ROM, but I neglected to modify the ROM address A16 logic...

Page 91 of 148 ---- Generated from RetroBrew Computers Forum Anyways, I've fixed the issue and posted the updated SPLD code on the GitHub. I've also updated the make_rom.sh to create ROMs for MSX2+.

--Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Sun, 22 Mar 2020 19:53:53 GMT View Forum Message <> Reply to Message Hello people, Someone very kind has sent me the corrected NTSC-BIOS files for the international keyboard.

My omega already works as an MSX2 +, it shows the logo and has the keyboard that corresponds to the characters you type.

I attach the file here temporally. https://drive.google.com/open?id=1heawxaSLOMHRaK2SyI1P-lILd5IxHykw

Kind Regards J. S. www.msxmakers.com

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Tue, 24 Mar 2020 19:21:32 GMT View Forum Message <> Reply to Message Guys, Maybe someone here would be interested on this thread. https://www.msx.org/forum/msx-talk/hardware/msx-usb?page=0

Regards.

J. S. http://www.msxmakers.com

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Thu, 26 Mar 2020 06:48:21 GMT View Forum Message <> Reply to Message Hi,

Page 92 of 148 ---- Generated from RetroBrew Computers Forum Using the BIOS image provided by Petr/Jordi, I've created a patch to update the keyboard layout of Japanese MSX2/MSX2+ BIOSes to international keyboard layout. The patch and the updated make_roms.sh script are available on project's GitHub. The script now also generates an MSX2/MSX2+ ROM image (omega_msx2_msx2+_ntsc.bin).

On my machine, I've connected an external switch to the JP1 header, so that I can switch between MSX2 and MSX2+ BIOSes if needed.

Thanks, Sergey

File Attachments 1) Omega_ROM_Switch.jpg, downloaded 867 times

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Tue, 31 Mar 2020 21:16:11 GMT View Forum Message <> Reply to Message Hi all. I wonder how Petr did it because even looking at the source Assembler files is hard to me imagine how.

Otherwise I fount a little problem and I would like get help also on this. All chars are now ok but the slashbar what is yen symbol. I think is a bit different issue because when the system should print a \ it prints a Y (yen money symbol) on its place. So... when the DOS begins shows anything like a:Y> and not like a:\> and when you would like to go root directory you should type cd Y (you will write the yen simbol with the \ key)

Everything works even that, but again, this is anything that looks correctly in PAL version. I wonder if anyone can find a solution to that problem. Maybe understanding what refers to BIOS source codes at BIOS.MAC and KEYINT.MAC

If someone can solve this, please let me know. Jordi Solis MSXmakers!

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Tue, 31 Mar 2020 21:30:19 GMT View Forum Message <> Reply to Message

Page 93 of 148 ---- Generated from RetroBrew Computers Forum jordi.solis wrote on Tue, 31 March 2020 14:16Hi all. Otherwise I fount a little problem and I would like get help also on this. All chars are now ok but the slashbar what is yen symbol. I think is a bit different issue because when the system should print a \ it prints a Y (yen money symbol) on its place. So... when the DOS begins shows anything like a:Y> and not like a:\> and when you would like to go root directory you should type cd Y (you will write the yen simbol with the \ key)

Jordi Solis MSXmakers!

So far as I know, that's standard behavior on Japanese MS-DOS based systems, and since MSX-DOS is derived from MS-DOS I wouldn't be worried about it. It should work and act as if it were a \

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Tue, 31 Mar 2020 23:31:39 GMT View Forum Message <> Reply to Message That is the expected behavior since Petr only modifed the keyboard mapping code. The font in the BIOS is still a Japanese one. If you look at the MSX fonts here https://www.msx.org/wiki/MSX_font, character 0x5C in the international font is "\", while in Japanese font it is yen sign. This can be fixed by modifying the font. I'll take a stab at that later.

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Thu, 02 Apr 2020 06:08:53 GMT View Forum Message <> Reply to Message Sergey wrote on Tue, 31 March 2020 16:31That is the expected behavior since Petr only modifed the keyboard mapping code. The font in the BIOS is still a Japanese one. If you look at the MSX fonts here https://www.msx.org/wiki/MSX_font, character 0x5C in the international font is "\", while in Japanese font it is yen sign. This can be fixed by modifying the font. I'll take a stab at that later. This raises an interesting question, have you shipped any boards to Japan? I wonder if the hobbyist culture over there is aware of this project.

MSX is a bit of a novelty for people in the US, and difficult to find in Europe and elsewhere, but it was mainstream there.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Thu, 02 Apr 2020 09:31:17 GMT

Page 94 of 148 ---- Generated from RetroBrew Computers Forum View Forum Message <> Reply to Message Hummm I wonder if their MSX DOS always looked like this... A:Y>

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Thu, 02 Apr 2020 09:49:52 GMT View Forum Message <> Reply to Message People, I fount anything who can help http:// www.msxarchive.nl/pub/msx/emulator/system_roms/nms8280-2plus -german-roms.zip Hans Oranje did a job on the MSX2+ BIOS and adapted it to german or international standards. I will try latter if it directly works with the OMEGA. ;-)

There's a big amount info to look at on https://hansotten.file-hunter.com/do-it-yourself/msx2-upgrades/

Jordi Solis.

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Thu, 02 Apr 2020 13:09:22 GMT View Forum Message <> Reply to Message jordi.solis wrote on Thu, 02 April 2020 02:31Hummm I wonder if their MSX DOS always looked like this... A:Y> It's been many years since I owned a PC-9801 laptop but as I recall, the built-in basic did, and so did the DOS version used. The lines through the Y made it obvious that it wasn't a normal capital Y though so you wouldn't really notice otherwise. It was CGA on a monochrome display so the resolution was probably the same.

Honestly, I don't really understand why or how this could be a problem? The system can't tell the difference, everything treats it the exact same way. The only difference is the visual representation.

EDIT: Come to think of it, $ was a prompt for many operating systems in the past, so why would anyone find ¥ surprising is beyond me to comprehend.

Subject: Re: MSX2 Compatible Computer Project Posted by tangent on Thu, 02 Apr 2020 17:20:51 GMT

Page 95 of 148 ---- Generated from RetroBrew Computers Forum View Forum Message <> Reply to Message It has been this way since a Japanese electronic character set was first standardized: https://en.wikipedia.org/wiki/JIS_X_0201

You can even see this in Win10 if you change your command prompt font to MS Gothic :)

Subject: Re: MSX2 Compatible Computer Project Posted by andrii_kutepov on Mon, 06 Apr 2020 10:30:52 GMT View Forum Message <> Reply to Message Hello everyone, how do you think such a device will work with Omega? https://www.msx.org/wiki/Carnivore2 https://github.com/RBSC/Carnivore2

Subject: Re: MSX2 Compatible Computer Project Posted by martin8bity on Tue, 07 Apr 2020 13:43:29 GMT View Forum Message <> Reply to Message andrii_kutepov wrote on Mon, 06 April 2020 12:30Hello everyone, how do you think such a device will work with Omega? https://www.msx.org/wiki/Carnivore2 https://github.com/RBSC/Carnivore2 Sure, it does http://www.8bity.cz/2020/carnivore2-compact-flash-vce-pameti -a-lep-zvuk-pro-msx/. For audio to work you must have +/-12V power supply or another solution, such as http://www.8bity.cz/2020/power-module-12v-for-omega-home-com puter/.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Wed, 08 Apr 2020 13:40:36 GMT View Forum Message <> Reply to Message Thanks Martin ;-) What about those PCBs:

https://www.msx.org/forum/msx-talk/hardware/1024kb-memory-up grade-yamaha-msx2-yis503?page=0 https://github.com/RBSC/F4-FMPAC

Does anybody tested them with the Omega Home Computer? thanks.

Page 96 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 08 Apr 2020 15:13:39 GMT View Forum Message <> Reply to Message jordi.solis wrote on Wed, 08 April 2020 06:40 https://www.msx.org/forum/msx-talk/hardware/1024kb-memory-up grade-yamaha-msx2-yis503?page=0

This one is designed specifically for Yamaha YIS503. Also, Omega already provides 512KiB RAM. If that is not enough, it can be easily extended up to 4 MiB using the connector on the right side. The schematic and the PCB would be really simple. Just connect the signals to up to 7 512 KiB SRAM ICs. All the logic is already implemented on the main board.

Quote: https://github.com/RBSC/F4-FMPAC

This probably will work. Although it can be significantly simplified: Omega would not need a ROM for FMPAC, there's plenty of space in system flash ROM. F4 port - I am still confused as for why one would need it (maybe for Mega RAM loaders, so they can reset the system without erasing RAM content?!). But if needed all the port F4 decode logic can be made into an ATF16F8 SPLD. The same SPLD can be also used for YM2413, a.k.a. OPLL. The sound output can be fed back to Omega, so that the analog / opamp part can be omitted as well. Unless you want stereo sound.

Let me know if you're interested in either one of the options. I can help with the design.

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Thu, 09 Apr 2020 13:23:31 GMT View Forum Message <> Reply to Message I don't know whether the Carnivore cart will work with the omega, it overrides memory mapping and most of it really isn't necessary when you can get a Sunrise IDE cart for a third of the price and that gives you a CF card interface.

Frankly the biggest problem with the omega is the lack of a floppy drive interface, because connecting a floppy (or equivalent usb-floppy drive emulator) is the only way of actually loading any software onto the system at all. AFAIK both the sunrise and the carnivore require a floppy drive to format the CF or SD cards you'd use and you'd need to install NEXTOR/MSX-DOS on them in order to do something with them. Then you'd have to load all of the software you wanted to use on the cards via your PC.

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Thu, 09 Apr 2020 13:36:09 GMT View Forum Message <> Reply to Message

Page 97 of 148 ---- Generated from RetroBrew Computers Forum Sergey wrote on Wed, 08 April 2020 08:13jordi.solis wrote on Wed, 08 April 2020 06:40 Quote: https://github.com/RBSC/F4-FMPAC

Let me know if you're interested in either one of the options. I can help with the design.

I mean, it's your design man, and I'm crap at all of this stuff, but a place to plug in a floppy drive and an FM chip onboard would make this possibly the best MSX clone anyone has ever actually created. what i would wonder about is the memory mapping with regards to the FMPAC. it might require some redirects?

Subject: Re: MSX2 Compatible Computer Project Posted by borutk on Thu, 09 Apr 2020 14:19:41 GMT View Forum Message <> Reply to Message I really like the idea behind https://github.com/S0urceror/MSX-USB. Similar to Rookiedrive, but open source. You can even attach USB floppy drive if you want. I haven't tried it yet, pcbs are still being made in China. bo/

Subject: Re: MSX2 Compatible Computer Project Posted by lintweaker on Mon, 13 Apr 2020 09:48:52 GMT View Forum Message <> Reply to Message borutk wrote on Thu, 09 April 2020 16:19I really like the idea behind https://github.com/S0urceror/MSX-USB. Similar to Rookiedrive, but open source. You can even attach USB floppy drive if you want. I haven't tried it yet, pcbs are still being made in China. bo/ I've also made a MSX cartridge for it:

Page 98 of 148 ---- Generated from RetroBrew Computers Forum Working with S0urcerer to get my board going sw wise

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Mon, 13 Apr 2020 13:39:55 GMT View Forum Message <> Reply to Message lintweaker wrote on Mon, 13 April 2020 11:48 Working with S0urcerer to get my board going sw wise Good! Don't forget to work also in a Symbos driver, Rookie Drive does not have compatible driver for it yet.

Regards

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Mon, 13 Apr 2020 14:08:17 GMT View Forum Message <> Reply to Message bifo wrote on Thu, 09 April 2020 15:23 AFAIK both the sunrise and the carnivore require a floppy drive to format the CF or SD cards you'd use and you'd need to install NEXTOR/MSX-DOS on them in order to do something with them. Then you'd have to load all of the software you wanted to use on the cards via your PC. Hi, I have all the Carnivore components but it's still in my to do list. I'm not sure about Carnivore but with the rookie drive was easier as formatting it with windows 7 and copy all the files. Even the best way was start on BASIC with the cartridge ROM inside and "call fdisk". I don't know if carnivore has similar functionality but it should.

I will let you know as far as I get it working.

MSXmakers

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Mon, 13 Apr 2020 14:17:54 GMT View Forum Message <> Reply to Message [quote title=Sergey wrote on Wed, 08 April 2020 17:13] This one is designed specifically for Yamaha YIS503. Also, Omega already provides 512KiB RAM. If that is not enough, it can be easily extended up to 4 MiB using the connector on the right side. The schematic and the PCB would be really simple. Just connect the signals to up to 7 512 KiB SRAM ICs. All the logic is already implemented on the main board.

I took a look on your connector signals right know. I just thought you made this connector for

Page 99 of 148 ---- Generated from RetroBrew Computers Forum previous maiden board and so I didn't imagine you implemented all the logic on the main board.

I think you mean a design like this. Thank you to double check it. (I'm not so confident with my skills).

MSXmakers File Attachments 1) omega-ramexpansion.pdf, downloaded 119 times

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 13 Apr 2020 15:20:52 GMT View Forum Message <> Reply to Message jordi.solis wrote on Mon, 13 April 2020 07:17 I took a look on your connector signals right know. I just thought you made this connector for previous maiden board and so I didn't imagine you implemented all the logic on the main board.

I think you mean a design like this. Thank you to double check it. (I'm not so confident with my skills).

This looks good! When you design the PCB, it would be convenient if it can be connected on the right side of the main board (instead of going on the top). But it is really up to you. Do whatever fits better in your enclosure!

The only thing I can recommend adding, is buffering on /RD and /WR signals... That is probably not really required, but won't hurt. You can use a non-inverting logic gate to buffer these. Eg. 74AHCT32, 74HCT08 connecting both inputs of an OR/AND gate together. 74AHCT244 would work too, but it is a bigger package.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Mon, 13 Apr 2020 15:51:09 GMT View Forum Message <> Reply to Message Sergey wrote F4-FMPAC This probably will work. I ordered few F4-FMPAC boards to be built, so I will be able to test at all if it's working or not.

Quote: Although it can be significantly simplified: Omega would not need a ROM for FMPAC, there's plenty of space in system flash ROM. I will try to glue it myself. :roll: Quote: F4 port - If needed all the port F4 decode logic can be made into an ATF16F8 SPLD. A hint to do

Page 100 of 148 ---- Generated from RetroBrew Computers Forum it by myself would be good, It's easy to program a SPLD as replacement for a sequential logic (74LS74D)? Maybe I should consider the clock on the karnaugh's table? Quote: The same SPLD can be also used for YM2413, a.k.a. OPLL. I will need to check it's datasheet, I wonder it was so simple. Quote: The sound output can be fed back to Omega, so that the analog/opamp part can be omitted as well. So all that can be replaced by an SPLD and reprogramming the ROM? Quote: Unless you want stereo sound. I think it would be nice even some jumpers to select it. The worst thing is RGB connector has not spare pins for adding the stereo sound. :d

Quote: I can help with the design. I would be glad to get your help

Thanks. MSXmakers

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Mon, 13 Apr 2020 19:22:00 GMT View Forum Message <> Reply to Message As comented on the following web page: https://hansotten.file-hunter.com/do-it-yourself/msx2-upgrades/Quote: Add the F4 register required by Basic 3.0 Maybe we fount the only use for this F4 register Kind regards. MSXmakers

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 13 Apr 2020 19:43:05 GMT View Forum Message <> Reply to Message jordi.solis wrote on Mon, 13 April 2020 08:51 I ordered few F4-FMPAC boards to be built, so I will be able to test at all if it's working or not.

Keep us posted!

Quote:Quote:F4 port - If needed all the port F4 decode logic can be made into an ATF16F8 SPLD. A hint to do it by myself would be good, It's easy to program a SPLD as replacement for a sequential logic (74LS74D)? Maybe I should consider the clock on the karnaugh's table?

Page 101 of 148 ---- Generated from RetroBrew Computers Forum Well, you'll still need to use an external 74*74 flip-flop. While it is possible to implement registered logic in the SPLD, there is no way to reset it at power on. Something like this should work (equations for GALasm):

; FM chip select; FM I/O ports - 0x7C and 0x7D /FMCS = /IORQ * M1 * /A7 * A6 * A5 * A4 * A3 * A2 * A1 ; F4 port write - 0xF4 (connect to 74*74 CLK) /F4WR = /IORQ * M1 * A7 * A6 * A5 * A5 * /A3 * A2 * /A1 * A0 * /WR ; FM port read - 0xF4 (connect to SPLD OE pin 11) /F4RD = /IORQ * M1 * A7 * A6 * A5 * A5 * /A3 * A2 * /A1 * A0 * /RD ; F4 register output (connect D7 to D7 of cartridge, connect F4_Q to 74*74 Q output) D7.T = /F4RD * F4_Q

Quote:Quote:The same SPLD can be also used for YM2413, a.k.a. OPLL. I will need to check it's datasheet, I wonder it was so simple.

I didn't mean to implement the Y2413 in the SPLD, but just to implement the chip select logic - a replacement for IC2 and IC3 on the schematic. See equations above.

Quote:The sound output can be fed back to Omega, so that the analog/opamp part can be omitted as well. Just connect the SLT signal (see F4-FMPAC) schematic to slot pin #49, or through an RC (10 uF capacitor + 4.7 kOhm resistor) to pin 2 of U48 op amp on Omega. In this case single op amp can be used (the second op amp is used to buffer the signal for connecting external amplifier)

Quote:Quote: Unless you want stereo sound. I think it would be nice even some jumpers to select it. The worst thing is RGB connector has not spare pins for adding the stereo sound. :d

Actually OPLL produce mono output... so this is not relevant

Quote:Quote:I can help with the design. I would be glad to get your help I need to find a couple of hours. How about making a cartridge with F4 and FM-PAC, and perhaps a WD37C65 floppy controller?!

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 13 Apr 2020 19:49:11 GMT View Forum Message <> Reply to Message jordi.solis wrote on Mon, 13 April 2020 12:22As comented on the following web page: https://hansotten.file-hunter.com/do-it-yourself/msx2-upgrad es/Quote: Add the F4 register required by Basic 3.0 Maybe we fount the only use for this F4 register

It is not required by BASIC 3.0. It would work regardless. I've tried ;-) The only benefit seems to be the ability of warm resetting the system without clearing the memory

Page 102 of 148 ---- Generated from RetroBrew Computers Forum content. Which might be used by RAM mapper to launch the emulated mega ROM? maybe? Don't know...

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Tue, 14 Apr 2020 00:36:50 GMT View Forum Message <> Reply to Message Hi, I will start working on this tomorrow.

Sergey wrote on Mon, 13 April 2020 21:43 Actually OPLL produce mono output... so this is not relevant

I'm pretty sure YM2149 can produce stereo sound as shown in the N8 or SCGS schematics. Is a circuit quite similar to the one attached by me. If I'm not wrong CN10 is an stereo output jack, connected to the YM2413 outputs.

Quote: How about making a cartridge with F4 and FM-PAC, and perhaps a WD37C65 floppy controller?!

Sounds good. I have also pending to build a Multicontroller board. But my own goal is to have a long hat over the mainboard, like a 2nd floor with a turbo speed button selection, a WD35C65 floppy & IDE controller, an F4-FMPACK sound improvement, and seven AS6C4008 to extend the RAM. Of course all through hole. My case was design to fit a floppy drive from the beginning.

MSXmakers.

File Attachments 1) FM - Audio.pdf, downloaded 96 times 2) PSG - Impressora.pdf, downloaded 106 times

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 15 Apr 2020 06:00:28 GMT View Forum Message <> Reply to Message I've updated the make_roms.sh in the GitHub repository. Now it includes the patch to replace the yen sign with the backslash. It also includes the patch for the ROM flags (locations 0x2B and 0x2C) to indicate International rather than Japanese ROM. This can be useful in some cases, but harmful in others. For example some Konami games use these flags to switch between Japanese and English (Vampire Killer, The Treasure Of Usas), while others will not work on non Japanese-machine (Metal Gear).

Page 103 of 148 ---- Generated from RetroBrew Computers Forum Here is the list of the currently produced ROM images:

omega_msx2_ntsc.bin - MSX2 ROM based on Sanyo PHC-23J, international keyboard, patched backslash; and US/NTSC MSX2 C-BIOS omega_msx2_pal.bin - MSX2 ROM based on Philips NMS 8250; and EU/PAL MSX2 C-BIOS omega_msx2+_ntsc.bin - MSX2+ ROM based on Sanyo PHC-35J, international keyboard, patched backslash; and US/NTSC MSX2+ C-BIOS omega_msx2_int_ntsc.bin - MSX2 ROM based on Sanyo PHC-23J, international keyboard, patched backslash; and the same BIOS with "international" flags set omega_msx2_msx2+_ntsc.bin - MSX2+ ROM based on Sanyo PHC-35J, international keyboard, patched backslash; and the same BIOS with "international" flags set omega_msx2+_int_ntsc.bin - MSX2 ROM based on Sanyo PHC-23J, international keyboard, patched backslash, with "international" flags set; and MSX2+ ROM based on Sanyo PHC-35J, international keyboard, patched backslash

I personally run the last image on my machine, as it provides multiple combinations: MSX2 and MSX2+, Japanese vs. International. It should be fairly easy to modify the make_roms.sh script to generate whatever image variety you'd like. If you don't have Linux machine, I presume the script should be working in Cygwin environment. Otherwise feel free to PM me for a binary image.

Cheers, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Thu, 16 Apr 2020 03:36:46 GMT View Forum Message <> Reply to Message jordi.solis wrote on Mon, 13 April 2020 07:08bifo wrote on Thu, 09 April 2020 15:23 AFAIK both the sunrise and the carnivore require a floppy drive to format the CF or SD cards you'd use and you'd need to install NEXTOR/MSX-DOS on them in order to do something with them. Then you'd have to load all of the software you wanted to use on the cards via your PC. Hi, I have all the Carnivore components but it's still in my to do list. I'm not sure about Carnivore but with the rookie drive was easier as formatting it with windows 7 and copy all the files. Even the best way was start on BASIC with the cartridge ROM inside and "call fdisk". I don't know if carnivore has similar functionality but it should.

I will let you know as far as I get it working.

MSXmakers That's great news, thanks. My Sunrise CF adapter finally arrived and doesn't fit the slot in my old MSX2, so I'm kind of at a loss on how to move forward. I'll hopefully finish the Omega by the end of this month and can experiment with that. Either that, or remove the front of my old MSX2. The

Page 104 of 148 ---- Generated from RetroBrew Computers Forum slot would fit the cartridge fine, but the design of the Sunrise is frustratingly off-center.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Thu, 16 Apr 2020 06:06:31 GMT View Forum Message <> Reply to Message bifo wrote on Thu, 16 April 2020 05:36 That's great news, thanks. My Sunrise CF adapter finally arrived and doesn't fit the slot in my old MSX2, so I'm kind of at a loss on how to move forward. I'll hopefully finish the Omega by the end of this month and can experiment with that. Either that, or remove the front of my old MSX2. The slot would fit the cartridge fine, but the design of the Sunrise is frustratingly off-center. Hello, I guess you know, but be careful not to insert the cartridge on the opposite (reverse) side. It is strange that it does not enter your MSX slot as you say. On this page it says how to format the compact flash drive considering that you have a floppy drive. https://www.msx.org/wiki/Sunrise_Compact_Flash_Card_Interface If not, below, describe how this can also be done by formatting in FAT16 <32M. I think Windows 7 would do well by formatting a 30Mb partition on FAT16 (for example), but you can also change the partition type using a GNU-Linux computer. I'm not sure but maybe the CALL FORMAT command is integrated in the NEXTOR BIOS and in that case you could run it from BASIC. More information in: https:// www.konamiman.com/msx/nextor/docs/Nextor%202.0%20Getting%20S tarted%20Guide.pdf Here it mentions to use a Nextor kernel with Sunrise IDE driver. It also describes how to install it with an emulator, I think you can also install Nextor in the emulator and then simply dump the disk image onto the compact flash card (with some specific software for it).

I hope this helps

MSXmakers

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Thu, 16 Apr 2020 10:26:01 GMT View Forum Message <> Reply to Message jordi.solis wrote on Wed, 15 April 2020 23:06bifo wrote on Thu, 16 April 2020 05:36 That's great news, thanks. My Sunrise CF adapter finally arrived and doesn't fit the slot in my old MSX2, so I'm kind of at a loss on how to move forward. I'll hopefully finish the Omega by the end of this month and can experiment with that. Either that, or remove the front of my old MSX2. The slot would fit the cartridge fine, but the design of the Sunrise is frustratingly off-center. Hello, I guess you know, but be careful not to insert the cartridge on the opposite (reverse) side. It is

Page 105 of 148 ---- Generated from RetroBrew Computers Forum strange that it does not enter your MSX slot as you say. On this page it says how to format the compact flash drive considering that you have a floppy drive. https://www.msx.org/wiki/Sunrise_Compact_Flash_Card_Interfac e If not, below, describe how this can also be done by formatting in FAT16 <32M. I think Windows 7 would do well by formatting a 30Mb partition on FAT16 (for example), but you can also change the partition type using a GNU-Linux computer. I'm not sure but maybe the CALL FORMAT command is integrated in the NEXTOR BIOS and in that case you could run it from BASIC. More information in: https:// www.konamiman.com/msx/nextor/docs/Nextor%202.0%20Getting%20S tarted%20Guide.pdf Here it mentions to use a Nextor kernel with Sunrise IDE driver. It also describes how to install it with an emulator, I think you can also install Nextor in the emulator and then simply dump the disk image onto the compact flash card (with some specific software for it).

I hope this helps

MSXmakers The MSX2 form factor of my machine is a desktop with detached keyboard, and the cartridge slot is a bit deeper than the normal all-in-one keyboard models. The cartridge is a later revision from the russian groups which has both an IDE port and a CF port, you can see the specifications and pictures here. The left hand side is offset outwards to accommodate a portion of the logic. It should work perfectly in the Omega though, so it isn't without it's uses.

That model MSX2 also has only one cartridge slot, the secondary interface was used for a proprietary expansion port on the back. Once people have finished their Omegas, it might be useful to have some cartridge expander boards/kits available, various designs exist and allow one cartridge port to accommodate 4 carts and given that we'll need FDC, probably CF or SD interface, and FMPACs (possibly also the network cartridge as well) those cartridge slots run out quick.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Thu, 16 Apr 2020 17:49:34 GMT View Forum Message <> Reply to Message bifo wrote on Thu, 16 April 2020 12:26 ... the secondary interface was used for a proprietary expansion port on the back. Ok, is not propietary but some manufacturers did it (like my SVI 728). you just need a cable built with... 1 CCE50S-ND slot to ribbon connector 1 50 wires ribbon cable 1 1-1658527-5 standard ribbon header (female).

And so you will have a secondary slot.

Page 106 of 148 ---- Generated from RetroBrew Computers Forum MSXmakers ;-)

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Fri, 17 Apr 2020 06:54:01 GMT View Forum Message <> Reply to Message jordi.solis wrote on Thu, 16 April 2020 10:49bifo wrote on Thu, 16 April 2020 12:26 ... the secondary interface was used for a proprietary expansion port on the back. Ok, is not propietary but some manufacturers did it (like my SVI 728). you just need a cable built with... 1 CCE50S-ND slot to ribbon connector 1 50 wires ribbon cable 1 1-1658527-5 standard ribbon header (female).

And so you will have a secondary slot.

MSXmakers ;-) Thanks very much, but according to this page the even <-> odd pins are swapped around. I'm not sure what effect that would have on the slot pinout, if it would just flip it? I was searching for plans on slot expansions a while back and virtually all of them warned strongly that if you got a slot pinout wrong it was very possible to zap your MSX.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Fri, 17 Apr 2020 17:14:07 GMT View Forum Message <> Reply to Message bifo wrote on Fri, 17 April 2020 08:54 Thanks very much, but according to this page the even <-> odd pins are swapped around. I'm not sure what effect that would have on the slot pinout, if it would just flip it? I was searching for plans on slot expansions a while back and virtually all of them warned strongly that if you got a slot pinout wrong it was very possible to zap your MSX.

EDIT it would appear that the digikey parts 89150-0001 and C1EXS-5036G would be the best combination for mine, since the expansion port guides aren't in the center, in case anyone finds this. The CPC-400 has two guides. Thanks for checking twice my suggestion, please do not follow it. if pins are swaped you may fix it or you probably burn your msx. :d regards. MSXmakers

Page 107 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Sat, 18 Apr 2020 22:13:05 GMT View Forum Message <> Reply to Message Sergey wrote on Wed, 15 April 2020 08:00I I've updated the make_roms.sh in the GitHub repository. Now it includes the patch to replace the yen sign with the backslash. It also includes the patch for the ROM flags (locations 0x2B and 0x2C) to indicate International rather than Japanese ROM. This can be useful in some cases, but harmful in others. For example some Konami games use these flags to switch between Japanese and English (Vampire Killer, The Treasure Of Usas), while others will not work on non Japanese-machine (Metal Gear).

Hi, Using the attached script we can have both versions of MSX2+ BIOS and we just can change the language with the same BIOS version. we can add a switch to do it on the fly. I have tested it with "the treasure of usas" or "Vampire Killer" on the fly and it works, they change their language chars as soon as the screen is refreshed. Of course without rebooting :d :d :d

I think it could be a good choice to be able to play all games without changing the firmware chip.

MSXmakers. File Attachments 1) make_roms2.sh, downloaded 149 times

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Tue, 28 Apr 2020 13:51:08 GMT View Forum Message <> Reply to Message Hi Guys, It seems like the bill of materials for the Omega keyboard has an issue. the 1x8 leveling kit for the space bar, is longer than should. I'm talking about the following p/n: Mouser 540-G99-0226 Anyobody knows the correct cherry part number for the 6.25 long bar? thank for helping me.

J. S.

Subject: Re: MSX2 Compatible Computer Project Posted by martin8bity on Tue, 28 Apr 2020 14:32:00 GMT View Forum Message <> Reply to Message I do not know if better part exists, but it was quite easy to straighten the bar and make the angle in

Page 108 of 148 ---- Generated from RetroBrew Computers Forum correct place.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Tue, 28 Apr 2020 15:22:32 GMT View Forum Message <> Reply to Message I don't think Cherry made 6.25U spacebar stabilizers, at least I can't find the part. They did make 7U ones, but Mouser doesn't have them. Just as Martin mentioned, it is not difficult to bend and shorten a 8U stabilizer. If I recall correctly the distance between the bends is 100 mm For my own builds I used a third-party stabilizers from eBay, but that seller doesn't have them any more.

Subject: Re: MSX2 Compatible Computer Project Posted by borutk on Wed, 29 Apr 2020 06:19:07 GMT View Forum Message <> Reply to Message I used these and they work great: https://www.ebay.com/itm/4-2x-1-6-25x-Plate-PCB-Mechanical-K eyboard-Cap-Stabilizer-For-Cherry-MX-Switch/173770800977?ssP ageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 It just took a while for the packet to get here from China.

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Wed, 29 Apr 2020 15:08:48 GMT View Forum Message <> Reply to Message borutk wrote on Tue, 28 April 2020 23:19I used these and they work great: https://www.ebay.com/itm/4-2x-1-6-25x-Plate-PCB-Mechanical-K eyboard-Cap-Stabilizer-For-Cherry-MX-Switch/173770800977?ssP ageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 It just took a while for the packet to get here from China. I bought both stabilizer kits linked in the BOM and the spacebar one was completely useless, but luckily the one for the various other keys which need it (enter, shift, backspace, etc) came with two extra stablizer-things which lock to the board at the end of the spacebar and the other keys through the holes designed into the board.

I do not know what the metal is for, but otherwise the spacebar leveler should probably be removed from the BOM, the metal doesn't fit the spacebar on the keyboard on the ANSI layout at all and the feet don't come with the bottom parts to attach it to the board at all. It's a total waste of money.

Page 109 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Sun, 03 May 2020 17:23:05 GMT View Forum Message <> Reply to Message Sergey wrote on Mon, 13 April 2020 21:43jordi.solis wrote on Mon, 13 April 2020 08:51 I ordered few F4-FMPAC boards to be built, so I will be able to test at all if it's working or not.

Keep us posted!

I am building the F4-FMPAC As I currently don't have the 27c256 chip, I understand that I can add this program to the current OMEGA's firmware chip. But I don't know how to do it. I don't understand the current memory structure inside the firmware chip very well, to know in which order I have to add this binary file to the current script. I only see that the script joins some files and also it leaves some blank spaces but I don't know where I will insert this file so that it matches the original location of an msx2. (How those 256k fits with the full slot/subslot addressable capacity)

Along with this question, also... , you mentioned that you could change the GAL mapper so that the memory expansion would be in slot 3-0 instead of 3-2. How could I do it?

Again with the FMPAC board, it requires me to take several signals from an empty cartridge. Is that so? This it the only way to use this board? The signals it requires are SLTSEL and CS1 from an unused slot (connected to CE and OE pins), and also some other signals such as SNDIN, +12, -12, GND that, although they are not required from a slot, are also available there.

Why do I have to lose a slot to have FMPAC? What is the difference using this board with the computers motherboards that already have included it?

Connecting the SLT output to the pin 2 of the opamp (U48) is a possibility. What if I connect there or to soundin? ok, I think you mentioned this to save some components like the op amp on the current FMPAC board.

I have also finished a design for the expanded memory card but I do not quite understand how you would like to connect it. Maybe you mean through a right angle header? As if it were a side extension module?

Thanks for your support. Regards.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Mon, 04 May 2020 11:22:30 GMT View Forum Message <> Reply to Message jordi.solis wrote on Sun, 03 May 2020 19:23

Page 110 of 148 ---- Generated from RetroBrew Computers Forum Again with the FMPAC board, it requires me to take several signals from an empty cartridge. Is that so? This it the only way to use this board? The signals it requires are SLTSEL and CS1 from an unused slot (connected to CE and OE pins), and also some other signals such as SNDIN, +12, -12, GND that, although they are not required from a slot, are also available there. Why do I have to lose a slot to have FMPAC? What is the difference using this board with the computers motherboards that already have included it?

Ok, I've got my answer. tThey are only needed for the EEPROM chip operation.

Thanks for helping me on the rest of questions. kind regards.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Wed, 06 May 2020 16:47:13 GMT View Forum Message <> Reply to Message Hi again, pending for components I'm working on modifying the BIOS SPLD as I think is needed. I have programed the expanded RAM on Subslot 3-0 like most of the msx2+ computers. Also modified the BIOS files to include the FMMUSIC ROM. It would be very kind of you (anyone) double checking what I did on the attached files to verify if that should work or letting me know what's wrong. Best regards.

Jordi Solis MSXmakers!

File Attachments 1) make_roms_fmpac.sh, downloaded 80 times 2) omega-slot_select_mod.pld, downloaded 91 times

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Sat, 09 May 2020 01:18:04 GMT View Forum Message <> Reply to Message I mentioned this a while back, but really just started working on it. I don't have a working Omega at this time, but based on the KiCad files, I have been doing some measurements and planning. This is still a work in progress, and I really just started. But hope to have it ready for a test print in the next few weeks since I'm working in my spare (limited) time. This is nowhere near ready, as it still needs some work on the back for the various ports, and come cosmetic alterations for aesthetics. But I've ironed out the general shape that I was going for, I still need to contour the

Page 111 of 148 ---- Generated from RetroBrew Computers Forum design... The idea was to emulate a true MSX style case. Critics are welcome share input.

The cone shaped standoffs are designed that way to improve the rigidity of the design. This is a large case (350mm x 230mm x 49mm). Not to mention they provide a little stronger mount for the PCB. I'm designing them for 4mm x 5mm M3 brass inserts. The idea is that the main board will mount in the lower shell, and the keyboard in the upper. It would be nice if there were keyboard plates that would fit this, as it would simplify not only the mounting of the keyboard, but would serve to remove any flex the PCB may end up having.

That said, even my new Core XY printer with a build volume of 330x330x400 is going to need to print these in half. And I'll need to weld them together (I have a plastic filament pen).

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Sat, 09 May 2020 01:47:15 GMT View Forum Message <> Reply to Message Hi Doug,

That looks really nice. I think the opening for the joystick ports on the front should be higher up. Since you'll be splitting the print, it would be nice if the case could be printed on 200 mm x 200 mm bed. You can refer to my DXF files for dimensions here: https://github.com/skiselev/omega/tree/master/Enclosure Although the diameter of S-Video opening could be 2 mm larger...

Thanks, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Sat, 09 May 2020 02:13:22 GMT View Forum Message <> Reply to Message Sergey,

Thanks for the input. I plan on posting the files both split, as well as complete, in case anyone wants to modify the design. I'll take a look at the dxf files when I get a moment.

As for joystick ports, there is a cutout underneath to accommodate the ports. The slot you're seeing in the front is minimal to allow the cables to rest underneath. So it won't necessitate a

Page 112 of 148 ---- Generated from RetroBrew Computers Forum larger opening.

I'm also considering a rotating cover for the cartridge ports, similar to the Casio MX-10, to keep dust out.

It's a work in progress. But I hope to have it a little more refined soon.

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Sat, 09 May 2020 22:03:30 GMT View Forum Message <> Reply to Message Making some additional progress on the case today. Thought I would post some pictures. I'm badge could be painted a different color, then snapped into place...

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Tue, 12 May 2020 00:43:13 GMT View Forum Message <> Reply to Message A little more work, and a few more renderings to see how it's coming along.

I'm planning on uploading two basic versions of this case. One to fit the stock boards. The second will remove the hole for the DC jack, and add a round hole and a square hole for a flush seated screw in DC jack (Lumberg 1614 10) and a rocker switch (11x45mm) for a power switch. This second version will also have mounting brackets for a small PSU (This version is for guys like me that would prefer to have a DC jack in something other than 5v: I'm scared to death of killing a board by plugging in a 12v PSU). Both versions will have a 11x45mm cutout for a rocker switch above the printer port for the ROM select switch. Though, this feature can always be extruded shut if it is not desired, or if you prefer something of a different footprint.

Currently, the standoffs for the keyboard are 8.5mm high, with a case thickness of 2.5mm. This makes the bottom of standard cherry style switch and cap about a hair below the top of the case. It's what sounded good to me, nearly flush with the bottom of the caps. But I'm game for accepting input. Let me know what you think.

Page 113 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Wed, 13 May 2020 23:28:05 GMT View Forum Message <> Reply to Message I've reached a point in case design that I'm ready to test print. I've verified all the hole locations for the PCB. So now it's time to see if I've made any bone head mistakes. I do not have enough PLA on hand to print the entire thing, so I've ordered some more. This shouldn't slow me down too much as these prints are going to take a while at the 30mm/s print speed that I'm using. Close to 20hrs a print for the shell halves. There are four of these. So, yeah...it's going to take a while. Individual print size is approximately 175mmx250mm. I've attached a few renderings of the nearly complete design below.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 13 May 2020 23:32:53 GMT View Forum Message <> Reply to Message Looks great! Good luck with printing!

Subject: Re: MSX2 Compatible Computer Project Posted by mikemac on Thu, 14 May 2020 01:09:39 GMT View Forum Message <> Reply to Message I may have missed the info: what are you using to design the case with? The results look very professional as if you've done this once or twice before.

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Thu, 14 May 2020 04:22:45 GMT View Forum Message <> Reply to Message mikemac wrote on Wed, 13 May 2020 18:09I may have missed the info: what are you using to

Page 114 of 148 ---- Generated from RetroBrew Computers Forum design the case with? The results look very professional as if you've done this once or twice before. Mike, I'm using 123D. As for printing I'm using a Tronxy X5SA, with a 330x330 build plate. Though, I plan on cutting the design files down to a reasonable 200x200 for those with smaller machines. As for having done it before, I have. But not quite this nice. A special machine deserves a special case to put it in. And I wanted this to look like a real MSX.

Also, if you go back through the previous pages of this thread, I posted some pictures of a ZX Spectrum case I did, that has a built in mechanical keyboard. It's not as nice as this, but was my take on what the spectrum might have been like with a mechanical keyboard.

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Thu, 14 May 2020 04:56:29 GMT View Forum Message <> Reply to Message That case looks fantastic, I especially like the door for the cartridge slots.

Subject: Re: MSX2 Compatible Computer Project Posted by mikemac on Thu, 14 May 2020 18:08:28 GMT View Forum Message <> Reply to Message jdgabbard wrote on Wed, 13 May 2020 21:22mikemac wrote on Wed, 13 May 2020 18:09I may have missed the info: what are you using to design the case with? The results look very professional as if you've done this once or twice before. Mike, I'm using 123D.

I wasn't clear but I was asking about the modeling/3D design SW. But I see 123D has been discontinued by Autodesk. So my search for a 3D design package continues.

Thanks for the info.

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Thu, 14 May 2020 22:22:27 GMT View Forum Message <> Reply to Message mikemac wrote on Thu, 14 May 2020 11:08jdgabbard wrote on Wed, 13 May 2020 21:22mikemac wrote on Wed, 13 May 2020 18:09I may have missed the info: what are you using to design the case with? The results look very professional as if you've done this once or twice before. Mike, I'm using 123D. I wasn't clear but I was asking about the modeling/3D design SW. But I see 123D has been discontinued by Autodesk. So my search for a 3D design package continues.

Thanks for the info.

Page 115 of 148 ---- Generated from RetroBrew Computers Forum Mike, 123D can still be downloaded. The online portion doesn't work though. So you lose that feature. It's still a powerful package though.

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Thu, 14 May 2020 22:24:17 GMT View Forum Message <> Reply to Message bifo wrote on Wed, 13 May 2020 21:56That case looks fantastic, I especially like the door for the cartridge slots.

Thanks! I should have the design verified as soon as I can finish printing. After that I'll share the STL files.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Mon, 18 May 2020 13:34:46 GMT View Forum Message <> Reply to Message Hi Guys, Look at what I fount on ebay: https:// www.ebay.es/itm/Omega-MSX2-Homebrew-Computer-IC-Kit/11410590 0693?hash=item1a913dde95:g:8O0AAOSw2bReP8n0 In theory is a kit with all chips for the omega at a good price, however, I'm not sure about them. some of the chips are replaced and, as I far as I know that 74LS can not be mixed with 74HC, I'm not sure about the rest: Is a AM29F040B a good substitute for the SST39SF040? what about the rest? Even if this is not a perfect solution can be a way to get it quite cheap. Do you agree? Let me know your comments.

Jordi from MsxMakers

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Mon, 18 May 2020 21:55:09 GMT View Forum Message <> Reply to Message As far as I know the only LS chips that are used in the Omega are the 2 for the 74LS07 which are behind HCT chips? I don't think mixing HC and LS will work? The CMOS vs TTL power requirements.

Page 116 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 18 May 2020 22:08:19 GMT View Forum Message <> Reply to Message bifo wrote on Mon, 18 May 2020 14:55As far as I know the only LS chips that are used in the Omega are the 2 for the 74LS07 which are behind HCT chips? I don't think mixing HC and LS will work? The CMOS vs TTL power requirements. It is usually OK to mix 74HCT (note the 'T' at the end, it means TTL-compatible) with 74LS. Mixing 74HC with 74LS might be problematic, particularly when connecting 74LS outputs to 74HC inputs.

Nothing to do with power requirements. The incompatibility is because the Vih (logic "high" input voltage) of 74HC (and CMOS in general, but not 74HCT/74AHCT/74ACT) is higher than the Voh (logic "high" output voltage) of the TTL ICs. Therefore when 74LS outputs logic "high", CMOS logic is not guaranteed to read it as "high"... It will be in a gray/invalid area, and sometimes CMOS will read it as "high", other times as "low". It might even oscillate... who knows ;-)

By the way, the recommended cartridge slot buffers are also TTL (74F, but 74LS/74ALS will work too). This is because MSX standard specifies that the cartridge interface should be TTL compatible. I suspect 74HCT/74AHCT would work just as well...

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Mon, 18 May 2020 22:33:22 GMT View Forum Message <> Reply to Message jordi.solis wrote on Mon, 18 May 2020 06:34Hi Guys, Look at what I fount on ebay: https:// www.ebay.es/itm/Omega-MSX2-Homebrew-Computer-IC-Kit/11410590 0693?hash=item1a913dde95:g:8O0AAOSw2bReP8n0 In theory is a kit with all chips for the omega at a good price, however, I'm not sure about them. some of the chips are replaced and, as I far as I know that 74LS can not be mixed with 74HC, I'm not sure about the rest: Is a AM29F040B a good substitute for the SST39SF040? what about the rest? Even if this is not a perfect solution can be a way to get it quite cheap. Do you agree? Let me know your comments.

Jordi from MsxMakers AM29F040B is a good replacement for SST39SF040. I think there is a sector size difference, but since we are not programming (yet) Flash ROM in system, it doesn't matter. If we ever support that, the Flash utility will need to take care of the chip differences (not difficult, I've done that for my 8088-based designs). Using 74HC instead of 74HCT/74AHCT (as the Omega design specifies) might be problematic.

Page 117 of 148 ---- Generated from RetroBrew Computers Forum I've seen such kits for other projects, including some of my designs. I assume someone in China scans the Internet for interesting designs, and offers "kits" that include whatever ICs they could find. Generally, I would recommend to avoid buying these kits, or any other components from China, unless these components cannot be purchased through legitimate channels (Mouser, Digikey, Avnet, etc), or local to your country/region suppliers. There are some philosophical and practical reasons behind this recommendation: - The components from China are frequently recycled, sometimes relabeled, sometimes faulty - I'd rather pay money to the original manufacturer. Some manufacturers are willing to help with component availability, e.g. back in 2012 when I designed Zeta SBC, Zilog didn't offer Z84C0020PEG (20MHz CMOS Z80 CPU) parts in single quantities. After buying a batch of the relabeled, and partially defective parts from China, I've contacted Zilog marketing, and they've worked with Mouser to offer the single quantities - I don't want to support Chinese chip counterfeiting/relabeling industry - I don't want to support not honest people. You do understand that "New: A brand-new, unused, unopened, undamaged item in the original package" and "Country / Region of Manufacture: Japan" description is a BS. Why not to be honest and specify, old/used/re-manufactured?

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Tue, 19 May 2020 03:20:12 GMT View Forum Message <> Reply to Message Making some headway on the case. I have the lower printed, and have begun using my 3d printing pen to "weld" it together. Printing the top half now. When this is done, I would highly suggest using rafts. I'm getting warping even with PLA due to the size and the fact that my Core-XY printer is not enclosed. Some eye candy for you.

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Tue, 19 May 2020 03:40:49 GMT View Forum Message <> Reply to Message Looks good. Is it more than 20 cm in depth? Also, I am wondering if it is possible to make some kind of joint between the plates (something like puzzle joints) so that they would fit better together, and it will be possible to glue them with a regular glue as opposed to the 3D printing pen?

Page 118 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Tue, 19 May 2020 04:32:52 GMT View Forum Message <> Reply to Message Hey, Sergey.

No, currently the largest size is about 175x190mm. It's going to be hard to make it any smaller without cutting it into a bunch of smaller pieces that are just going to be more difficult to put together and maintain proper alignment.

As for the joints, you could. But in my experience those puzzle type joints don't normally work out as well as a standard straight joint that has been properly epoxied, or "welded" together. I have tried it a few times, and they just don't slice properly, and cause misalignments.

Proper fusion can normally be achieved by screwing the board down to all of the pieces (to align it), then making small tacks with some spare filament and a dedicated soldering iron tip. Once these tacks are in place you can either weld it with a 3d pen, or use epoxy. Then sand smooth, primer, and paint.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Tue, 19 May 2020 13:40:29 GMT View Forum Message <> Reply to Message Sergey wrote on Tue, 19 May 2020 05:40 Looks good. Is it more than 20 cm in depth? Also, I am wondering if it is possible to make some kind of joint between the plates (something like puzzle joints) so that they would fit better together, and it will be possible to glue them with a regular glue as opposed to the 3D printing pen? I made it in a previous project. a modular s100 card cage. I just added a hole and a bar who was just 0.2mm less in its diammeter (Im not sure maybe twice) they just fit and was not possible to disjoint. you can check it at those files:

File Attachments 1) OpenSCAD.tar.7z, downloaded 82 times

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Tue, 19 May 2020 13:53:23 GMT View Forum Message <> Reply to Message jdgabbard wrote on Tue, 19 May 2020 06:32oard down to all of the pieces (to align it), then making small tacks with some spare filament and a dedicated soldering iron tip. Once these tacks are in place you can either weld it with a 3d pen, or use epoxy. Then sand smooth, primer, and

Page 119 of 148 ---- Generated from RetroBrew Computers Forum paint. Of course to me, this sounds more aligned, beauty result and clear plan. we can also my do my suggestion leaving more slack between the pieces, to permit alignment, then glue, sand and paint. Regards.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Tue, 19 May 2020 13:59:38 GMT View Forum Message <> Reply to Message jdgabbard wrote on Tue, 19 May 2020 06:32 Creator of the G80-S Micro Computer and 'Porter' of TinyBASIC 2.5g Hi, another issue. Is there possible to compile the tinyBASIC for MSX and load it once C-BIOS started? I know that N8 Home computer is not an MSX standard computer but he has C-BIOS and BASIC, It could be possible to do anything similar with the OMEGA HOME COMPUTER, when using a c-bios firmware? let me know. regards.

Subject: Re: MSX2 Compatible Computer Project Posted by andrii_kutepov on Wed, 20 May 2020 07:42:31 GMT View Forum Message <> Reply to Message I ask for help in one matter. I'm starting the build Omega and don't know if to collect nodes for PAL image output. I can't make PAL-NTSC modes flexible. Resistor R9 and Cap C91 must be different and soldered for different modes. How is it done with you?

Thanks Andrii

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 20 May 2020 19:00:15 GMT View Forum Message <> Reply to Message Hi Andrii,

The Omega Motherboard is designed to support either NTSC or PAL, but it is not designed to be easily switchable between two.

Page 120 of 148 ---- Generated from RetroBrew Computers Forum With that being said, I've used NTSC values for R9 and C91 (20 kOhm and 27 pF respectively) on one of my boards, and it still works with PAL, although NTSC values might negatively impact the output quality.

C91 and L1 are only used for Composite Video output, they should not impact the RGB or S-Video quality. But if you insists on using the right value you can either install a connector (e.g. use pins from machined sockets) for C91, so you can change it if needed, or solder a 18 pF capacitor on the board and when needed connect another 10 pF capacitor in parallel for NTSC operation (e.g. using a jumper or a socket).

For R9 you can use 16 kOhm and 4 kOhm resistors connected in series, so that the resulting resistance is 20 kOhm. For the PAL operation short-circuit the 4 kOhm resistor (e.g using a jumper connected in parallel with that resistor), which will give you 16 kOhm

Thanks, Sergey

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 20 May 2020 19:05:10 GMT View Forum Message <> Reply to Message jordi.solis wrote on Tue, 19 May 2020 06:59 Is there possible to compile the tinyBASIC for MSX and load it once C-BIOS started? I know that N8 Home computer is not an MSX standard computer but he has C-BIOS and BASIC, It could be possible to do anything similar with the OMEGA HOME COMPUTER, when using a c-bios firmware?

I suspect it is possible. But I don't have time or desire to do that at this point ;-)

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Wed, 20 May 2020 20:08:11 GMT View Forum Message <> Reply to Message jordi.solis wrote on Tue, 19 May 2020 06:59jdgabbard wrote on Tue, 19 May 2020 06:32 Creator of the G80-S Micro Computer and 'Porter' of TinyBASIC 2.5g Hi, another issue. Is there possible to compile the tinyBASIC for MSX and load it once C-BIOS started? I know that N8 Home computer is not an MSX standard computer but he has C-BIOS and BASIC, It could be possible to do anything similar with the OMEGA HOME COMPUTER, when using a c-bios firmware? let me know. regards.

Page 121 of 148 ---- Generated from RetroBrew Computers Forum It's very possible. Though TB 2.5g (my custom version of TB) is much less feature rich as MSX Basic. Given the capabilities of what the MSX has already, I'm not sure why you'd want to, unless it was to have more user space available. But even then, with the extra routines you'd need to make it useful to the MSX, you probably wouldn't gain much user space once you factored in the way you program TB versus MSX basic.

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Wed, 20 May 2020 20:13:14 GMT View Forum Message <> Reply to Message jordi.solis wrote on Tue, 19 May 2020 06:53jdgabbard wrote on Tue, 19 May 2020 06:32oard down to all of the pieces (to align it), then making small tacks with some spare filament and a dedicated soldering iron tip. Once these tacks are in place you can either weld it with a 3d pen, or use epoxy. Then sand smooth, primer, and paint. Of course to me, this sounds more aligned, beauty result and clear plan. we can also my do my suggestion leaving more slack between the pieces, to permit alignment, then glue, sand and paint. Regards. I don't normally add space between the parts, just sand them down to fit properly. But it can be done. I also sent to chamfer the edges with a 0.75mm edge to get a good weld. It's a lot like welding steel. It gives you a good strong bead that you can sand down flush with careful work of a Drexel.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Sat, 23 May 2020 10:56:13 GMT View Forum Message <> Reply to Message [quote title=jdgabbard wrote on Wed, 20 May 2020 22:08][quote title=jordi.solis wrote on Tue, 19 May 2020 06:59]jdgabbard wrote on Tue, 19 May 2020 06:32 It's very possible. Though TB 2.5g (my custom version of TB) is much less feature rich as MSX Basic. Given the capabilities of what the MSX has already, I'm not sure why you'd want to, unless it was to have more user space available. But even then, with the extra routines you'd need to make it useful to the MSX, you probably wouldn't gain much user space once you factored in the way you program TB versus MSX basic. my only purpose was to have anything useful to start with c-bios and also for testing purposes. I have not any game cartridge, and for any reason I cannot start nextor on my Rookie Drive with c-bios. I'm thinking on someone who has c-bios working but not MSXBIOS and he can run some out/poke comands.

What I should do to have it? just compile-link and add the file to the current firmware?

PS: use MSXBASIC cannot be legal at all and some like me bet for GPL as much as we can. 8) 8) regards

Page 122 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Sat, 23 May 2020 11:19:12 GMT View Forum Message <> Reply to Message If someone want to know it I added an F4/FMPAC to my Omega computer and now some games sound actually nice. As I would like to save the cartridge slots I didn't added the eprom chip to this board and just added the binary file to the current OMEGA firmware. It just need to connect +-12v power source to JP1 on FMPAC board, and AMP/GND connection to pin 2,4 of U48 in the Omega motherboard. Now Aleste sounds fantastic but a little bit low. I will try to decrease the value for resistor R4 on the FMPAC board and let you know (I discovered the schematic shows 4k7 but the silkscreen 2k2) regads J S

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Sat, 23 May 2020 11:47:30 GMT View Forum Message <> Reply to Message I hope someone can help me. I don't have a PAL monitor (neither a NTSC one). At the beginning I tested the Omega with NTSC configuration and a composite to SCART cable connected to a standard LED TV. Then I changed the configuration on the board and tested it with PAL, but nothing was displayed on TV. After that I knowed that the RGB connection was actually better image and built a cable from DIN-8 to SCART. Then I was able to display images even if PAL or NTSC configuration was implemented. following the Sergey instructions some components must be removed, replaced and some jumpers must be swapped. Ok, Now I would like to know how it works in deep, because even if I left JP3-JP4 in any possition, even if I left all the components like Y3 installed, and even if left R9 and C91 in old values, I can display images everytime on my TV and just the BIOS kind switches what is the working speed. With a PAL bios some games like IKARI are shown wrong and some like Aleste are slow even playing music. Does it mean the PAL circuit of my Omega runs as should but I don't have a PAL TV or maybe anything connected to RGB is not "PAL". To leave my building instructions as clear as possible I would prefer everyone soldering all the components what don't disturb. regards

Page 123 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by ls120nz on Tue, 26 May 2020 01:42:35 GMT View Forum Message <> Reply to Message how goes the case ?? any more pic's ?? thanks for your work on it..

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 27 May 2020 21:50:17 GMT View Forum Message <> Reply to Message jordi.solis wrote on Sat, 23 May 2020 04:47 With a PAL bios some games like IKARI are shown wrong and some like Aleste are slow even playing music. Does it mean the PAL circuit of my Omega runs as should but I don't have a PAL TV or maybe anything connected to RGB is not "PAL".

PAL BIOS configures VDP for 50 Hz refresh rate, while NTSC BIOS configures VDP for 60 Hz. This happens regardless of JP5 and JP6 jumper settings. These jumpers only switch the timing and the video output standard for the CXA1645 encoder, and I think they only impact the S-Video and composite video, not the RGB. (By the way, you wrote JP3 and JP4. I assume it is a mistake. These jumpers have nothing to do with PAL or NTSC. They select between V9938 and V9958 and must match the VDP, or bad things will happen). On each screen refresh VDP generates an interrupt, and that interrupt is commonly used for synchronization. So if you run a game designed to work with 60 Hz NTSC system, it will appear to be sluggish on 50 Hz PAL system. And vice versa, if you run PAL game on NTSC, it will appear to run faster.

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Thu, 28 May 2020 09:16:21 GMT View Forum Message <> Reply to Message jordi.solis wrote on Sat, 23 May 2020 04:47I hope someone can help me. I don't have a PAL monitor (neither a NTSC one). At the beginning I tested the Omega with NTSC configuration and a composite to SCART cable connected to a standard LED TV. Then I changed the configuration on the board and tested it with PAL, but nothing was displayed on TV. After that I knowed that the RGB connection was actually better image and built a cable from DIN-8 to SCART. Then I was able to display images even if PAL or NTSC configuration was implemented. following the Sergey instructions some components must be removed, replaced and some jumpers must be swapped. Ok,

Page 124 of 148 ---- Generated from RetroBrew Computers Forum Now I would like to know how it works in deep, because even if I left JP3-JP4 in any possition, even if I left all the components like Y3 installed, and even if left R9 and C91 in old values, I can display images everytime on my TV and just the BIOS kind switches what is the working speed. With a PAL bios some games like IKARI are shown wrong and some like Aleste are slow even playing music. Does it mean the PAL circuit of my Omega runs as should but I don't have a PAL TV or maybe anything connected to RGB is not "PAL". To leave my building instructions as clear as possible I would prefer everyone soldering all the components what don't disturb. regards I know that the little LCD screen I purchased a while ago for project work with composite input is auto-switching between PAL and NTSC frequencies, it's possible that the screen you're using isn't one that switches automatically? Or if the game's programming relies on timing from the NTSC side of things and setting the timing to PAL causes it to stumble, since they're both japanese (NTSC) games.

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Thu, 28 May 2020 09:58:16 GMT View Forum Message <> Reply to Message Question/suggestion for Jordi: which chip is superior, the https://en.wikipedia.org/wiki/Yamaha_YM2608 or the https://en.wikipedia.org/wiki/Yamaha_YMF278 from moonsound? The through-hole version of the YMF278 lost functionality, where on the YMF288 version of the YM2608 lost functionality, and the YM version is 64-pin through hole. It requires a support chip in the design, but I am not remotely knowledgeable enough to design anything with it. I'm also not sure whether they share similar address requirements and I don't know if the YM2608 could drop in as a replacement on a Moonsound clone, but i would think it would just require some slight re-routing in programming. Sort of like using a Roland D-110 in place of an MT-32.

Again, I have no idea of the complexity of this, but I do know that YM2608s are probably the most impressive chips of that era and they are through-hole 64-dip. Only a suggestion, since it's incredibly difficult to build a Moonsound at home.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Thu, 04 Jun 2020 08:42:32 GMT View Forum Message <> Reply to Message Sergey wrote on Wed, 27 May 2020 23:50 PAL BIOS configures VDP for 50 Hz refresh rate, while NTSC BIOS configures VDP for 60 Hz. This happens regardless of JP5 and JP6 jumper settings. These jumpers only switch the timing and the video output standard for the CXA1645 encoder, and I think they only impact the S-Video and composite video, not the RGB. (By the way, you wrote JP3 and JP4. I assume it is a mistake. These jumpers have nothing to do with PAL or NTSC. They select between V9938 and V9958 and must match the VDP, or bad things will happen).

Page 125 of 148 ---- Generated from RetroBrew Computers Forum On each screen refresh VDP generates an interrupt, and that interrupt is commonly used for synchronization. So if you run a game designed to work with 60 Hz NTSC system, it will appear to be sluggish on 50 Hz PAL system. And vice versa, if you run PAL game on NTSC, it will appear to run faster.

Thanks for your answer. For some reason I have stopped receiving response notifications to this forum in my email account, so until today I did not know that you responded to me.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Thu, 04 Jun 2020 08:51:51 GMT View Forum Message <> Reply to Message [quote title=bifo wrote on Thu, 28 May 2020 11:16]jordi.solis wrote on Sat, 23 May 2020 04:47 Then I changed the configuration on the board and tested it with PAL, but nothing was displayed on TV. bifo wrote on Thu, 28 May 2020 11:16 I know that the little LCD screen I purchased a while ago for project work with composite input is auto-switching between PAL and NTSC frequencies, it's possible that the screen you're using isn't one that switches automatically? Or if the game's programming relies on timing from the NTSC side of things and setting the timing to PAL causes it to stumble, since they're both japanese (NTSC) games. Thanks bifo This problem is solved. Currently if I configure OMEGA for PAL it already works emitting video through the composite video output.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Thu, 04 Jun 2020 09:16:46 GMT View Forum Message <> Reply to Message bifo wrote on Thu, 28 May 2020 11:58Question/suggestion for Jordi: which chip is superior, the https://en.wikipedia.org/wiki/Yamaha_YM2608 or the https://en.wikipedia.org/wiki/Yamaha_YMF278 from moonsound? ... I am not an expert in this matter, but from what I have asked, and according to the specification, the opl4 is much higher. It has twice as many fm channels and it also has 24 pcm / wave channels. In fact opl3 is also better than that 2608.

I have only managed to successfully operate the FMPAC in OMEGA, so I am happy.

When I have time I will work on giving my MSX better sound alternatives. When I have any progress I will let you know but this is long term.

Page 126 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Thu, 04 Jun 2020 09:26:03 GMT View Forum Message <> Reply to Message http://Hi, I made my first design for the O4MEGA (Omega 4Mb expansion). I think is not what would Sergey suggested but it would be easy to modify (as far as I understood what kind of connector you will put on to your motherboard). I will share it on my github as soon as I can. here you are a picture I also successfully added F4/FMPAC to my OMEGA, Aleste sounds now actually nice. https:// www.instagram.com/p/CA93MrhHz37/?utm_source=ig_web_copy_link regards.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Thu, 04 Jun 2020 11:37:30 GMT View Forum Message <> Reply to Message jordi.solis wrote on Sat, 23 May 2020 13:19

I will try to decrease the value for resistor R4 on the FMPAC board and let you know (I discovered the schematic shows 4k7 but the silkscreen 2k2) regads J S

680 ohms to 1K would be nice on R4. Better than 2k2 original value J. S.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Thu, 04 Jun 2020 11:42:13 GMT View Forum Message <> Reply to Message Here a nice computer 3d case. Perhaps any of you can take advantage from this... https:// www.thingiverse.com/thing:4303511?fbclid=IwAR1nGShqrjLCFMfez syz1S0WJQ8LDQQuGPJo3WN4As9EZBDHcLGWwl-Fx-g

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Thu, 11 Jun 2020 09:37:58 GMT View Forum Message <> Reply to Message

Page 127 of 148 ---- Generated from RetroBrew Computers Forum I would like to know what is the purpose for the 3 trimcaps. I checked at the schematic their function and all them are connected to a crystal so, Are they maybe to adjust a bit the frequence value. I just soldered them in any value and everything is working. A college lost them and tried without them installed. it was successfully working to (at least through RGB connection). can anyone confirm its use? regards.

Subject: Re: MSX2 Compatible Computer Project Posted by rodneyj on Fri, 12 Jun 2020 04:41:43 GMT View Forum Message <> Reply to Message This is mentioned in the BOM list,

Note: Can be replaced with Mouser 810-FG28C0G2A270JNT0 if color subcarrier frequency tunning is not required.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Fri, 12 Jun 2020 17:33:51 GMT View Forum Message <> Reply to Message Thank you rodneyj, Sorry for my ignorance but there are 3 trimcaps, is the carrier adjusted on the PAL frequency, and also on the main frequency (which I assume is the NTSC frequency in addition to being the system clock)? What about the capacitor in the RTC, also the RTC has a carrier? I thought the carrier signal was something associated with video signals.

I am not understanding video signals, what effect will I see by adjusting the carrier, maybe better video quality?

Cheers.

Subject: Re: MSX2 Compatible Computer Project Posted by rodneyj on Mon, 15 Jun 2020 04:05:24 GMT View Forum Message <> Reply to Message Hi Jordi, looking at the schematic, each of the trimcaps appear to provide adjustments for each of the

Page 128 of 148 ---- Generated from RetroBrew Computers Forum oscillator circuits. C89 relating to the oscillator for the V9938/V9958 (which the V9958 outputs for the system clock & NTSC clock as you've said), C90 for the PAL oscillator, depending on the PAL/NTSC build option this oscillator feeds into the CXA1645 pin 6, the subcarrier input.

C88 appears to be related to the onbaord RTC (as you already mentioned) and has nothing to do with the subcarrier.

My understanding the cxa1645 really only buffers the RGB signal and only the sync will be affected by the subcarrier frequency, so may be the impact on the RGB output is very little. regards Rodney.

Subject: Re: MSX2 Compatible Computer Project Posted by ls120nz on Fri, 19 Jun 2020 09:59:08 GMT View Forum Message <> Reply to Message any info on the f4 etc... fix and ram upgrade?

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Fri, 19 Jun 2020 15:49:32 GMT View Forum Message <> Reply to Message Hi, I have the current design of the ram upgrade here: https://github.com/msx-solis/O4MEGA it's just few ram chips and a 74HCT08. about the F4/FMPAC you will find all the infomation here: https://github.com/RBSC/F4-FMPAC if you plan to use it with the OMEGA, you don't need to use the eeprom chip, you don't need to use JP1 and JP4, so you don't need to spend an MSX slot on it, just add the FMPAC rom to your SST39SF040, and connect the +-12 imput and amp/gnd to pins 2&4 pins of U48. to convine O4MEGA and FMPAC upgrades you need to use smd capacitors on C1, C2 and C3. enjoy it. If you like I have few boards available. Regards.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Sat, 20 Jun 2020 20:41:51 GMT View Forum Message <> Reply to Message

Page 129 of 148 ---- Generated from RetroBrew Computers Forum Hi, I have an omega with Black screen (a college close to me). We are trying all what we know to find the issue. We fount that with C-BIOS ROMS the computer beep several times. Anyone knows what does it mean?

I will appreciate if someone helps me with the answer or better with a link with the solution. regards.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Sun, 21 Jun 2020 20:44:17 GMT View Forum Message <> Reply to Message Ok, it was not a beep but a noise produced by a broken Z80. C-bios produces no beeps, it can show a light blue on screen even without RAM, RP5C01, ... even without VRAM chips it will show the blue background Thanks anyway

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Tue, 07 Jul 2020 11:22:01 GMT View Forum Message <> Reply to Message Hi all, Some people here reported problems with few cartridge games and the Omega home computer. Would anyone confirm any of those games are working with its Omega (only cartridge version)? It seems that is focused on 32K games because most of 16K and megarom are working.

The Goonies: screen with few green lines, then reboot. Once and again, and again... Knightmare: the game starts but all graphics and tiles are wrong. roller ball (de halm 16KB): starts directly to msBASIC. raid on bungelin bay (de sony, 32KB): a half of the screen on blue and the other black. Pacman: black screen.

Kind regards. J.S. MSXmakers

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Tue, 07 Jul 2020 11:41:37 GMT View Forum Message <> Reply to Message

Page 130 of 148 ---- Generated from RetroBrew Computers Forum sorry,

PACMAN: White screen (the game always begin with a white screen).

Regards.

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Fri, 10 Jul 2020 06:55:48 GMT View Forum Message <> Reply to Message jordi.solis wrote on Tue, 07 July 2020 04:22Hi all, Some people here reported problems with few cartridge games and the Omega home computer. Would anyone confirm any of those games are working with its Omega (only cartridge version)? It seems that is focused on 32K games because most of 16K and megarom are working.

Kind regards. J.S. MSXmakers

Does anyone still have a stock of MSX EPROM cartridge boards left? They're in the board inventory but nobody is listed as a contact. I still haven't finished building my omega (life, etc) but I have a tl866 and a UV eraser and I figured I'd build one or two cartridges at some point anyway. I could test on my NTSC MSX2 and then on my omega once it's completed to compare.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Fri, 10 Jul 2020 15:20:30 GMT View Forum Message <> Reply to Message Hi All, I have fixed the problem. There was a bug on the slot dir gal code. The new code can be downloaded from ow is corrected on the Sergey's github.

About the cartridge board, it was an old design with sources lost. hopefuly I needed to build a cartridge to test the above problem and it was actually easy to use one of the msx-pi boards (I have some available) to build the cartridge. It's not actually cute because the ROM chip in on the back. I will modify this kicad to get a 32k cartridge soon. I will let you know when I got it.

Page 131 of 148 ---- Generated from RetroBrew Computers Forum Regards. msxmakers.com

Subject: Re: MSX2 Compatible Computer Project Posted by borutk on Tue, 14 Jul 2020 20:48:13 GMT View Forum Message <> Reply to Message Jordi,

Your O4MEGA ram expansion module is nice idea but the board is interfering with one of the keyboard supports. Could you modify it so it would have a hole in the correct place?

Best regards, Bo/

Subject: Re: MSX2 Compatible Computer Project Posted by Sergey on Wed, 15 Jul 2020 15:44:15 GMT View Forum Message <> Reply to Message jordi.solis wrote on Fri, 10 July 2020 08:20Hi All, I have fixed the problem. There was a bug on the slot dir gal code. The new code can be downloaded from ow is corrected on the Sergey's github.

Jordi, thanks for finding and fixing this issue/typo.

Everyone who have built an Omega, please reflash your U14 / Slot Direction SPLD. The updated fuse map is in the GitHub repo here

-SK

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Fri, 17 Jul 2020 06:28:57 GMT View Forum Message <> Reply to Message borutk wrote on Tue, 14 July 2020 22:48Jordi,

Your O4MEGA ram expansion module is nice idea but the board is interfering with one of the keyboard supports. Could you modify it so it would have a hole in the correct place?

Best regards,

Page 132 of 148 ---- Generated from RetroBrew Computers Forum Bo/ the space was very tight and does not fit very well with the F4/FMPAC module. I think I will have to start by versioning that module, and do it on the spaces of the motherboard itself. That way I can locate all the holes. J.S.

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Wed, 05 Aug 2020 01:24:15 GMT View Forum Message <> Reply to Message Sergey,

I finally got all my parts together, and installed in the Omega. But I'm having a few issues with the keyboard.

Mainboard version is 1.1, and Keyboard is version 1.0. The only parts not installed on the keyboard are the resistor network, and D1 power LED. RR7 on the mainboard is present. However, I'm getting weird functioning when I press keys on the keyboard. When I press '0' the screen displays '08', when I press space it displays '0 *' occasionally the Code LED lights up randomly.

Any pointers?

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Wed, 05 Aug 2020 22:50:58 GMT View Forum Message <> Reply to Message Disregard. I had misunderstood the directions. I thought the Keyboard RN1 had been removed and moved over to the PCB on Mainboard v1.1. However, I then realized that it was still needed. All works great now, and runing MSX2+_int_NTSC flawlessly.

Now if only my SD-512 that I dumped quite a bit on several years ago actually worked, I'd be in heaven.

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Sat, 08 Aug 2020 14:32:46 GMT View Forum Message <> Reply to Message jordi.solis wrote on Sat, 23 May 2020 04:19If someone want to know it I added an F4/FMPAC to my Omega computer and now some games sound actually nice. As I would like to save the cartridge slots I didn't added the eprom chip to this board and just added the binary file to the current OMEGA firmware. It just need to connect +-12v power source to JP1 on FMPAC board, and AMP/GND connection to pin 2,4 of U48 in the Omega motherboard.

Page 133 of 148 ---- Generated from RetroBrew Computers Forum Now Aleste sounds fantastic but a little bit low. I will try to decrease the value for resistor R4 on the FMPAC board and let you know (I discovered the schematic shows 4k7 but the silkscreen 2k2) regads J S

Jordi,

Since I got my Omega running the other day I got to thinking about the FM-PAC. And it may be easy to simplify the design further, omitting the +12v rail. Looking at the schematic, it appears that it's only needed for the amplifier. But other designs for computers often use just a 5v rail, such as with the schematic below. Of course, it would need a few changes, such as the 10uF cap and 4.7k resistor to be tied into the Omega's audio circuit. But that is trivial. Have you though about this?

File Attachments 1) 6238CD9B-0226-4DB1-B032-129E43DB8164.png, downloaded 646 times

Subject: Re: MSX2 Compatible Computer Project Posted by bifo on Sun, 09 Aug 2020 13:43:29 GMT View Forum Message <> Reply to Message jdgabbard wrote on Wed, 05 August 2020 15:50Disregard. I had misunderstood the directions. I thought the Keyboard RN1 had been removed and moved over to the PCB on Mainboard v1.1. However, I then realized that it was still needed. All works great now, and runing MSX2+_int_NTSC flawlessly.

Now if only my SD-512 that I dumped quite a bit on several years ago actually worked, I'd be in heaven. Does your SD-512 itself not work or have you found a compatibility issue with it and the Omega? I've got one and haven't tried it yet, but I had wondered how it would interact with the onboard memory map and how it tries to run NEXTOR.

Subject: Re: MSX2 Compatible Computer Project Posted by jdgabbard on Thu, 13 Aug 2020 13:39:08 GMT View Forum Message <> Reply to Message bifo wrote on Sun, 09 August 2020 06:43jdgabbard wrote on Wed, 05 August 2020 15:50Disregard. I had misunderstood the directions. I thought the Keyboard RN1 had been removed and moved over to the PCB on Mainboard v1.1. However, I then realized that it was still needed. All works great now, and runing MSX2+_int_NTSC flawlessly.

Page 134 of 148 ---- Generated from RetroBrew Computers Forum Now if only my SD-512 that I dumped quite a bit on several years ago actually worked, I'd be in heaven. Does your SD-512 itself not work or have you found a compatibility issue with it and the Omega? I've got one and haven't tried it yet, but I had wondered how it would interact with the onboard memory map and how it tries to run NEXTOR. It works now. I bought it about two years ago, when I only had a MSX-1. And it was supposed to only give limited functionality, so I could never test it. But highly suspected something was wrong, because it tried to boot Nextor once, but then failed. And it never did this again. When I tried it in the Omega it wouldn't work. So I did some probing around and discovered the ROM's D0 line wasn't soldered on the socket. A fine tip iron fixed the problem.

I'm now running nextor 2.1 DOS 2, and have full access to the file system as well as the MegaRAM. It doesn't appear to show the 512k when in Mapper Mode. But the MegaRAM functions fine. Sofa run works great. I haven't tried SymbOS, so I'm not sure about that.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Wed, 19 Aug 2020 02:04:22 GMT View Forum Message <> Reply to Message jdgabbard wrote on Sat, 08 August 2020 16:32

Jordi,

Hi Doug. Thank you for your suggestion. Forgive my ignorance, but what I understand according to the diagram you show me is that we can use 5v operational amplifiers and not 12v, is that correct? As for the resistor and the capacitor, I see that they are connected in a different way than the FMPAC scheme does. it's correct? I don't know how to calculate their values. I was working on reducing the scheme with a GAL as Sergey suggested but I discovered that I did not know as much about the GAL as I thought, I am not sure I have enough knowledge to transform the information Sergey gave me into a JED file. This is the configuration that Sergey suggested: ; FM chip select; FM I / O ports - 0x7C and 0x7D / FMCS = / IORQ * M1 * / A7 * A6 * A5 * A5 * A3 * A2 * A1 ; F4 port write - 0xF4 (connect to 74LS74 CLK) / F4WR = / IORQ * M1 * A7 * A6 * A5 * A5 * / A3 * A2 * / A1 * A0 * / WR ; FM port read - 0xF4 (connect to SPLD OE pin 11) / F4RD = / IORQ * M1 * A7 * A6 * A5 * A4 * / A3 * A2 * / A1 * A0 * / RD

Page 135 of 148 ---- Generated from RetroBrew Computers Forum ; F4 register output (connect D7 to D7 of cartridge, connect F4_Q to 74LS74 Q output) D7.T = / F4RD * F4_Q

I have detected that he has repeated * A5 instead of A4 and I am no longer sure what his intention was.

It would be very nice not to have to use the 12v power supply. The audio output of my FMPAC connects to the motherboard's op amp through a resistor and capacitor in series, I don't know how to calculate the correct value in the circuit you show. Regards. J S

Subject: Re: MSX2 Compatible Computer Project Posted by kman on Wed, 19 Aug 2020 09:23:36 GMT View Forum Message <> Reply to Message I would suggest to use the LMV258 as replacement for the TL072, because the latter one is not specified for +5V single supply operation nor is the output voltage swing symmetric. The LMV258 can operate fron +2.7V... +5V5 and it's out swing is rail-to-rail. If using the voltage divider R5/R6 to have a +2.5V virtual ground U4B needs that too, otherwise it's +input will fall to virtual -2.5V and will drive it's output to ground and may be into nonlinear operation (if U3 does not supply a +2.5V offset at RO/MO outputs).

Kurt File Attachments 1) LMV258_LMV324.pdf, downloaded 94 times

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Thu, 20 Aug 2020 16:04:41 GMT View Forum Message <> Reply to Message I don't understand at all about op-amps. ¿is quite different than using a MCP6281 like the Omega does? it's also working with Vcc=5v. Regards. J S.

Subject: Re: MSX2 Compatible Computer Project Posted by kman on Thu, 20 Aug 2020 20:26:03 GMT View Forum Message <> Reply to Message I've briefly compared theire datasheets, the LMV258 is a general purpose low cost device whilst the MCP6281 has better parameters (and might be therefore more expensive). But it's ok to

Page 136 of 148 ---- Generated from RetroBrew Computers Forum choose the MCP6281. Both can operate/are specified at/for +5V. As a quick hack I've modified the schematic with gimp to show a possible configuration. Increasing R3/R4 reduces the signal amplitude (coming from U3) at Pin5 of U4B and vice versa. The two 10k create a ~2.5V working point for U4B. I've used this for my Multicomp analog joystick inputs and found that it works very well with a single supply and a non negativ going ground based signal. Nevertheless you should check wether it is usefull for you.

Kurt File Attachments 1) Modified_Sound-Interface.png, downloaded 91 times

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Fri, 21 Aug 2020 17:28:02 GMT View Forum Message <> Reply to Message Very good, Well, I use the F4 / FMPAC module as a mixer input in OMEGA: U48. I connect the AMP -GND output of the FMPAC to pins 2-4 of U48. Is it safe to do this with the circuit you send me? What security measure could I take, do I compare the signals with the oscilloscope? Thanks in advance.

Subject: Re: MSX2 Compatible Computer Project Posted by kman on Sat, 22 Aug 2020 15:36:04 GMT View Forum Message <> Reply to Message > Well, I use the F4 / FMPAC module as a mixer input in OMEGA: U48. I connect the AMP -GND output of the FMPAC to pins 2-4 of U48. yes you can, but a additional summing-R for U48 is needed: see Summing_R-Network_U48.png

> Is it safe to do this with the circuit you send me? > What security measure could I take, do I compare the signals with the oscilloscope?

1. you should delete the marked resistor in the schematic: see Modified2_Sound-Interface.png 2. you should measure the amplitude that are feed to the summing network of U48 from the F4/FM-Pack. The amplitude should be in the same range as from the other sound sources (that simplifies life). Check that the sum of all sources does not overdrive U48 on its output. If the amplitude needs some adjustment, try to adjust R3 & R4. Rxx for U48 should be left as is to keep the voltage range the same for all inputs.

I have always a bad feeling using elkos when the DC potential on both legs is on the same level

Page 137 of 148 ---- Generated from RetroBrew Computers Forum (due to the polarized nature of elkos). Check the DC-level on both sides, the (+)-leg should be more positive then the (-)-leg (obvious fact, but this thought is based on some very exciting personal experiences I had during my business life with this ;-) ). If this can't be garantieed try to use a film capacitor or two elkos in +][- -][+ series connection.

Kurt File Attachments 1) Summing_R-Network_U48.png, downloaded 188 times 2) Modified2_Sound-Interface.png, downloaded 208 times

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Tue, 08 Sep 2020 15:43:51 GMT View Forum Message <> Reply to Message Thank you for your answer I didn't saw it until now. I mentioned that I sue the AMP output, so it includes a resistor and capacitor like in your defined schema, good. However the mixed sound from the FMPACK was too low and so I increased this by modifying R4 (like your Rxx) to 1k. I don't know if that was risky but it actually works. I can compare the current amplitude on the mixer and at the U48 output. Then I will probe what this schema does. thank you.

Subject: Re: MSX2 Compatible Computer Project Posted by jmannz on Mon, 21 Sep 2020 01:38:24 GMT View Forum Message <> Reply to Message Hi Another successful build here. Thank you for sharing. I do have one strange issue. I have built a few cartridges and they seem to function if the rom file is 16K or less. I did see the post about reprogramming the GAL and have done this but the issue remains. Have tried with PAL and NTSC bios with the same result. As i am yet to get a 32K file that works could somebody be so kind as to share or provide a link to a know good 32k rom file so i can test it.

Many Thanks John

Update: The 32k roms I have do work in a emulator but on the Omega

Page 138 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by jmannz on Tue, 06 Oct 2020 18:56:43 GMT View Forum Message <> Reply to Message Problem solved. Seems my lack of MSX knowledge was the issue. Swopping the upper and lower halves of the 32K ROMS solved the issue.

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Wed, 07 Oct 2020 06:59:50 GMT View Forum Message <> Reply to Message jmannz wrote on Mon, 21 September 2020 03:38Hi Another successful build here. Thank you for sharing. I do have one strange issue. I have built a few cartridges and they seem to function if the rom file is 16K or less. I did see the post about reprogramming the GAL and have done this but the issue remains. Have tried with PAL and NTSC bios with the same result. As i am yet to get a 32K file that works could somebody be so kind as to share or provide a link to a know good 32k rom file so i can test it.

Update: The 32k roms I have do work in a emulator but on the Omega Hi John, You say you built some cartridges? What schematic did you use? The problem may be with the connection design you are using. Does the /CS12 signal reach the enable chip correctly? I have used the schematic of the MSXpi card. With a 32K ROM chip you can activate /CS1 and load a 16K game (first half of memory) activate /CS2 and load another 16K game (second half) or activate the /CS12 signal if you have a game that occupies 32K. You can compare that scheme with yours to see if there are differences. regards.

Subject: Re: MSX2 Compatible Computer Project Posted by jmannz on Sat, 10 Oct 2020 03:48:21 GMT View Forum Message <> Reply to Message Hi Thanks for the reply. I have vert simple cartridge PCB's with jumpers (No mapper or other chips). the selections are select CS_1,CS_2 or CS_12 and connect to OE (Pin 22)

With CS_12 connected to Eprom OE (Pin 22) and halves swopped the rom works fine. as this is a 27C512 I have 2 x 32k roms and can select them by setting A15 low or high

Page 139 of 148 ---- Generated from RetroBrew Computers Forum https://github.com/Wierzbowsky/SGC_ImageCreator was the reason i tried swopping the halves

Regards John

Subject: Re: MSX2 Compatible Computer Project Posted by martinmurphy30 on Tue, 13 Oct 2020 20:32:50 GMT View Forum Message <> Reply to Message Hi guys, I'm new here and have also built a working omega. I have recently made myself a copy of The Cure and patched it to work on my hx-10, however it crashes on my omega (both patched and original ROM files) anyone else had this issue?

Subject: Re: MSX2 Compatible Computer Project Posted by jmannz on Sat, 17 Oct 2020 03:18:28 GMT View Forum Message <> Reply to Message @martinmurphy30

What size is your rom file?. Flick me copy or point me to obtain a copy and I will test it on my Omega.

Regards John

Subject: Re: MSX2 Compatible Computer Project Posted by martinmurphy30 on Sat, 17 Oct 2020 13:37:41 GMT View Forum Message <> Reply to Message Thanks for the reply John, the ROM is 48k and can be downloaded here:https://www.msxdev.org/msxdev-archive/msxdev05/ Will be interesting to see if it works for you.

Subject: Re: MSX2 Compatible Computer Project Posted by jmannz on Sat, 17 Oct 2020 22:42:16 GMT View Forum Message <> Reply to Message The Rom boots with the splash screen and then the next screen "Press fire" I don't have a joystick so no fire to press :) Then it restarts with the same sequence. So i can only assume this is normal behavior. This s the rom file as downloaded no patching.

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Subject: Re: MSX2 Compatible Computer Project Posted by jmannz on Sat, 17 Oct 2020 22:46:02 GMT View Forum Message <> Reply to Message Next question. Has anybody got a TDC:600 floppy controller or clone to work. Mine just goes to a blue screen. I have tried various rom versions all with the same result. Could somebody be so kind as to test a TDC:600 in the Omega

Many Thanks John

Subject: Re: MSX2 Compatible Computer Project Posted by martinmurphy30 on Sun, 18 Oct 2020 16:15:27 GMT View Forum Message <> Reply to Message After the press fire screen it should play the video intro and music, if it just restarts then it appears to be some kind of incompatibility with the omega. my copy plays perfectly on my hx-10, but crashes on the omega. Which bios are you using? I'm using a NTSC bios but mite try a pal one to see if it makes any difference.

Subject: Re: MSX2 Compatible Computer Project Posted by martinmurphy30 on Sun, 18 Oct 2020 16:18:44 GMT View Forum Message <> Reply to Message https://msxmakers.design.blog/proyectos/proyecto-tdc-600/ Jordi has tested the floppy controller on his omega and it works fine.

Subject: Re: MSX2 Compatible Computer Project Posted by jmannz on Mon, 19 Oct 2020 09:05:13 GMT View Forum Message <> Reply to Message martinmurphy30 wrote on Sun, 18 October 2020 09:18https://msxmakers.design.blog/proyectos/proyecto-tdc-600/ Jordi has tested the floppy controller on his omega and it works fine. Thank you

Subject: Re: MSX2 Compatible Computer Project

Page 141 of 148 ---- Generated from RetroBrew Computers Forum Posted by jordi.solis on Tue, 20 Oct 2020 14:14:09 GMT View Forum Message <> Reply to Message martinmurphy30 wrote on Sun, 18 October 2020 18:18https://msxmakers.design.blog/proyectos/proyecto-tdc-600/ Jordi has tested the floppy controller on his omega and it works fine. Thanks

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Tue, 20 Oct 2020 14:15:36 GMT View Forum Message <> Reply to Message I really had no idea that you were interested in my progress. I don't know if you can understand or translate my blog. Thanks for your interest. If someone wants to collaborate and help me by translating the content into English it would be wonderful. I thought everyone here knew like me or even more.

I intend to extend the omega with FM / MUSIC, Turbo button, a disk drive without wasting a slot, designing a wide case for the extensions, and of course I do not have that much time, any help is welcome.

I would also like to build a BUS monitor cartridge with stop and go, step by step and logic test. Surely it doesn't fit, well on multiple cards.

Subject: Re: MSX2 Compatible Computer Project Posted by martinmurphy30 on Thu, 22 Oct 2020 19:21:48 GMT View Forum Message <> Reply to Message I'm currently waiting for a few konami mapper prototype PCBs to be delivered, basically a konami PCB using a plcc 512k flash memory. I have a DIY Rom cart finalised which can accept 8k, 16k,32k and 64k eproms. Have been playing with a homebrew beer ide on my hx-10 and was considering making the floppy controller also, but was thinking of a cart with built in gotek. Any interest in this project? Can't decide whether to go the floppy/emulation route, or something like carnivore, sofarom etc...

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Sun, 08 Nov 2020 12:34:45 GMT View Forum Message <> Reply to Message Hi, I would like to share with all you we are working on a new Acrylic long case for the Omega and even it's a work in progress, I think we almost have it. of course I will share all designs with the community as soon as we consider it's finished.

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Kind regards.

Subject: Re: MSX2 Compatible Computer Project Posted by jmannz on Mon, 30 Nov 2020 03:20:18 GMT View Forum Message <> Reply to Message Hi Anybody made an ASCII mapper cartridge. I have one based on the schematic below but unfortunately is does NOT seem to work with any of the ACSII roms i have tried.

Thanks John File Attachments 1) acsii.JPG, downloaded 1189 times

Subject: Re: MSX2 Compatible Computer Project Posted by norwestrzh on Mon, 30 Nov 2020 17:07:17 GMT View Forum Message <> Reply to Message Hi John,

I don't know anything about MSX or "ASCII mapper cartridges", but I have used the 74LS670 quite successfully to interface a 512x8 SRAM to a Z80. It gives either 16k or 32k bank switching capability. Seems to work quite well. If you were using the older version (74LS170), I would suggest pull-ups on the outputs (open collector), but I guess that you are not. I could try to locate the schematics for my Z80 project if you thought that it might help? There was a guy who used this technique quite a while ago, but again, it was to expand the address space of a Z80. I think his name was Gormaker? (I could check that), and he wrote a little article about it. Maybe it is available on line somewhere?

Roger

[I just checked, and the name is Francis Gormarker. There are also schematics of my Z80 project on my Web site -- www.hanscom.us. Look at the "A Simple MMU for the Z80" tab.]

Page 143 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by martinmurphy30 on Tue, 01 Dec 2020 18:22:59 GMT View Forum Message <> Reply to Message Hi mate, I'm pretty sure that's actually a konami 128k mapper, I think the ASCII carts used a custom chip. Can you try running vampire killer or another konami 128k ROM to see if it works? I made the largest version using 2 74ls670's but so far I've had no luck getting it to work! :lol:

Subject: Re: MSX2 Compatible Computer Project Posted by martinmurphy30 on Tue, 01 Dec 2020 21:16:17 GMT View Forum Message <> Reply to Message Oops! Sorry hard to make out the chips used there but the konami mapper uses 1 74ls02 and the 74ls670, I see now there's a 74ls32 and possibly a 74ls00 in the schematic you posted. :roll:

Subject: Re: MSX2 Compatible Computer Project Posted by jmannz on Fri, 04 Dec 2020 08:38:54 GMT View Forum Message <> Reply to Message Hi Yip i modified the ascii mapper to a Zemina/Konanmi verison with the schematic below and it works perfectly. Just cant seem to get an ascii verison to work. I know we cant get megarom cartridges but i am going for a single cartridge look and feel. ( The single game cartridge really appeals to me)

The ASCII 8kb has the following mapping: Maybe there's a way to poke the address from basic and confirm the mapper is working correctly by checking the 74LS670 outputs (ideas welcome)

Bank 1: 4000h - 5FFFh Bank 2: 6000h - 7FFFh Bank 3: 8000h - 9FFFh Bank 4: A000h - BFFFh And the address to change banks:

Bank 1: 6000h - 67FFh (6000h used) Bank 2: 6800h - 6FFFh (6800h used) Bank 3: 7000h - 77FFh (7000h used) Bank 4: 7800h - 7FFFh (7800h used)

Regards John

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Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Wed, 09 Dec 2020 00:56:44 GMT View Forum Message <> Reply to Message martinmurphy30 wrote on Thu, 22 October 2020 21:21I'm currently waiting for a few konami mapper prototype PCBs to be delivered, basically a konami PCB using a plcc 512k flash memory. I have a DIY Rom cart finalised which can accept 8k, 16k,32k and 64k eproms. Have been playing with a homebrew beer ide on my hx-10 and was considering making the floppy controller also, but was thinking of a cart with built in gotek. Any interest in this project? Can't decide whether to go the floppy/emulation route, or something like carnivore, sofarom etc... I think a cartridge with HxC integrated would be nice. I'm interested, do you want support?

Subject: Re: MSX2 Compatible Computer Project Posted by jordi.solis on Wed, 16 Dec 2020 23:11:52 GMT View Forum Message <> Reply to Message Guys, you would like to know there's a new Omega's case design available. https://www.thingiverse.com/thing:4686651 cheers.

J. S. MSXmakers

Subject: Re: MSX2 Compatible Computer Project Posted by martinmurphy30 on Sat, 19 Dec 2020 12:37:23 GMT View Forum Message <> Reply to Message Hi Jordi, sorry I have been busy with work/ life recently. I have found a nice layout of the gotek on easyeda, just Google gotek easyeda and you will find it. I was in the process of working out what jumpers would be needed for msx but havent found a definite answer. The floppy controller chips are available in plcc format so it should be possible to build this as a single cart with oled display. As for support, feel free to do what you want I have so many projects on-going I don't know when Il get round to this! But if/when I do I will keep you posted and make any schematics, layouts etc available.

Subject: Re: MSX2 Compatible Computer Project

Page 145 of 148 ---- Generated from RetroBrew Computers Forum Posted by martinmurphy30 on Thu, 31 Dec 2020 00:52:22 GMT View Forum Message <> Reply to Message Hi John, I've attempted to build the zemina/konami mapper again in its simplest form as you posted but I cannot get this to work. Looking at the schematic A14 of the msx cart connector is not connected to anything? Is this correct? I seem to have no luck with msx hardware! Lol!

Subject: Re: MSX2 Compatible Computer Project Posted by borutk on Tue, 12 Jan 2021 20:30:16 GMT View Forum Message <> Reply to Message The problem with this mapper is that the translation is not initialized, because RAM has no predetermined initial value on power on. I guess that on reset, original Konami mapper presets at least translation for 0 and 1. So you have to first manually initialize at least locations 0 and 1, before you can run anything from the ROM.

Subject: Re: MSX2 Compatible Computer Project Posted by martinmurphy30 on Wed, 13 Jan 2021 09:33:53 GMT View Forum Message <> Reply to Message So how would you initialise them manually to get this to work? Thanks for the reply!

Subject: Re: MSX2 Compatible Computer Project Posted by martinmurphy30 on Wed, 13 Jan 2021 09:58:36 GMT View Forum Message <> Reply to Message Maybe il experiment with pull up resistors to set the bits to a 1 on power up? Any thoughts guys? Thanks for the reply!

Subject: Re: MSX2 Compatible Computer Project Posted by borutk on Fri, 15 Jan 2021 12:55:23 GMT View Forum Message <> Reply to Message Pull ups won't help, the values in the address translation (HC670) RAM are random at powerup. What you have to do is write a small program that initializes the values in address translator and than do a reset. Check that your modified mapper works both for reading and writing at the correct addresses.

Page 146 of 148 ---- Generated from RetroBrew Computers Forum Subject: Re: MSX2 Compatible Computer Project Posted by andrii_kutepov on Mon, 21 Jun 2021 14:43:00 GMT View Forum Message <> Reply to Message The project is completely finished. Was to builted and run a long time ago, but lacked little things. That's it now. A few photos for history

Subject: Re: MSX2 Compatible Computer Project Posted by tingo on Mon, 21 Jun 2021 15:30:33 GMT View Forum Message <> Reply to Message Beautiful - well done!

Subject: Re: MSX2 Compatible Computer Project Posted by lynchaj on Mon, 21 Jun 2021 20:28:56 GMT View Forum Message <> Reply to Message Very nice!

Subject: Re: MSX2 Compatible Computer Project Posted by bigpete on Thu, 15 Jul 2021 17:23:27 GMT View Forum Message <> Reply to Message That case looks fantastic!

Subject: Re: MSX2 Compatible Computer Project Posted by ABurrows on Sat, 18 Sep 2021 01:21:22 GMT

Page 147 of 148 ---- Generated from RetroBrew Computers Forum View Forum Message <> Reply to Message Could anyone suggest a link to the case design, or where i would be able to purchase one? andrii_kutepov wrote on Mon, 21 June 2021 07:43The project is completely finished. Was to builted and run a long time ago, but lacked little things. That's it now. A few photos for history

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