InSync Members’ News
TNMoC will be hosting a Members’ Open Day on Saturday 28th March 2015, 10:00am for 10:30am. This is your opportunity to share your ideas regarding the future of the membership programme.
Important changes are afoot both in the museum and in the Members’ organisation. We want you to be amongst the first to hear about them. In particular, we are keen to consult more with Members and to enable you to become more involved in the Museum. We’d like to share our plans with you during the open day and hear your views, so we hope that you will be able to attend.
The programme for the day will include an exclusive, in-depth look at the Cambridge University EDSAC reconstruction. If you’ve been to the museum recently you’ll have seen that the project is progressing very well. Members of the EDSAC team will be there to tell you all about it.
Volunteers and the Museum’s management team will be on hand to chat with Members about the museum and its ever-changing range of exhibits. If there is sufficient interest we will arrange one or more specialist guided tours for Members.
Full details will be sent to you nearer the time. If you have any questions you are invited to contact John Linford at [email protected]. In the meantime, please put the Open Day in your diary. We look forward to seeing you!
Connecting with the Museum of Computing Keep up to date with the latest information from the museum by visiting our various social media and website presences. The handy QR codes below will connect you to our website, Twitter, Facebook, Google Plus, Flickr and YouTube sources. If you are reading this newsletter on a computer or tablet device, then you can tap on the QR codes below or if you are reading a printed version, then scan these codes with a QR reader on a smart phone or tablet device. QR scanners are readily available from app stores (iTunes, Google Play, Windows phone stores). Just search for and install a free QR code reader to start using these codes. TNMOC also has an iPhone navigation app that is a great introduction to the experiences in store when visiting the museum.
TNMOC newsletter 2 Q1 2015 Members’ Club—a prospectus
Dear TNMoC member,
When I joined TNMoC as a member about a year ago, I had no real thoughts about what it meant beyond the wish to support the museum in a practical way. It soon became apparent that there was little in the way of member interaction. At the Members’ Day in March 2014 I was amazed to discover that we numbered just a few hundred.
Since then I have been working with the museum staff to find ways to improve what we offer in return for membership and I am now delighted to be able to announce that we will be forming a members’ club. The club will be self-supporting and will have a very close, well-defined relationship with the museum. It will have two principal objectives:
Substantial growth in numbers, to provide an increasing revenue to help develop the museum
Providing a range of events, activities and benefits for club members.
My feeling is that the membership represents a huge resource whose potential has not been realised. It is the club’s intention to foster membership interaction and participation. We are a diverse community and physical meetings are not always practical, but we will have various forms of on-line interaction through forums etc. We also want to improve the way the membership interacts with the museum, so that members can offer to assist in other ways if they wish.
We will be running a club Members’ Open Day on 28th March 2015. It will be an opportunity to find out more about our plans and to get an insider’s view of what’s going on at the museum. We would be delighted to see you there.
I mentioned on-line interaction. It is our intention to explore how best to provide this interactive environment but that will take time. Meanwhile, I am pleased to announce that we have set up a Yahoo! Group, which I very strongly encourage you to join. The Group will enable us to communicate with one-another and help us to be more informed about the museum and better engaged.
The Yahoo Group is at https://uk.groups.yahoo.com/neo/groups/tnmocmembers/info. You can join the Group from the web site or by sending an e-mail to [email protected]. As this is a private group for members only, you will then receive an e-mail asking you for your membership details. I will approve member applications as soon as I can, usually with 24 hours.
Everyone at the museum, from the trustees to the volunteers, is enthusiastic about this plan for a members’ club. I hope you share this enthusiasm and look forward to your participation.
Kind regards,
John Linford
TNMoC member 1234
We would love to hear from you if you have any stories for the newsletter.. They can be technical, personal or just observational in nature. You can contact us by email at: [email protected] to discuss your ideas or by regular post to:
InSync Editor, The National Museum of Computing, Block H, Bletchley Park, Milton Keynes, MK3 6EB
TNMOC newsletter Q1 2015 3 News desk
DSAC Project Chairman and very rare original part of he sounds and ecology of 70 entrepreneur, Hermann EDSAC, one of the world’s years of computing is the focus E Hauser, officially opened the A first computers, has T of a new Arts Council funded EDSAC display at TNMOC and, as resurfaced in the USA .The part, a project at TNMOC. The public will be key reconstructed parts of one of the chassis (1A) designed to hold 28 of able to listen as the project unfolds. most influential computers ever built the 3000 EDSAC valves, has been Later in the year a series of were commissioned, the sights, donated to the EDSAC team at extraordinary new musical sounds, heat and sheer size of early TNMOC, where the ongoing compositions will be published. 1940s computing were brought to reconstruction of EDSAC, originally The Imitation Archive is being life. built in Cambridge in the late produced by award-winning sound 1940s, is on display. The artist and composer Matt Parker. He At the official opening of the exhibit, reconstruction is expected to be will produce a permanent sound Bill Purvis showed how a program completed later in 2015 and is archive of the restored and would be input before the advent of already a very popular exhibit recreated working machines at the keyboards and how the result would especially amongst the many Museum. The archive, the first of its be output before screens became educational groups that visit the kind, will represent the phenomenal commonplace. Peter Linnington Museum. revealed how, delay lines were used progress of computing over the past as stores. As the climax, Chris The EDSAC Chassis part is said to 70 years. The archive will be made Burton switched on the EDSAC have been acquired at some sort of available to visitors at the museum clock, the machine’s beating heart. auction of EDSAC parts in as well as through The British Cambridge in the 1950s when the Library Sound Archive ensuring the The three-year project is on computer was decommissioned. global dissemination of the hugely schedule to complete in late 2015. significant working heritage Computer historian Martin Campbell Andrew Herbert, leader of the machines at the Museum. -Kelly revealed plans for young EDSAC reconstruction project said: people run their own programs on “Details of the ‘auction’ are unclear, Once recorded and archived, Matt the reconstructed machine. but there is a possibility that other will use the audio material to create parts of the original EDSAC still a series of interlinked musical EDSAC Project leader, Andrew exist and could even be in the compositions that will reflect the Herbert, said: “We are incredibly Cambridge area stored away in development of computing from the fortunate to have a volunteer team lofts, garden sheds and garages. code-breaking Colossus computer with a rare skill set, including We would very much like to hear up to the present day. Machines that students of the original computer from anyone who thinks they may are expected to be recorded include pioneers and members of the last have other parts.” the wartime Robinson and Tunny generation to be trained in the use of code breaking equipment, the thermionic valves. The team doesn’t The part has been donated by world’s oldest original working digital have blueprints to follow, so we Robert Little, from Allentown, computer the Harwell Dekatron / have to adopt a 1940’s mindset to re Pennsylvania, USA, after he read WITCH, the large systems of the -engineer and redesign the about the EDSAC reconstruction 1960s and mainframes. machine.” project. He obtained the part in 1969 from Dr Robert E Clark, who Sneak previews of the work are Doron Swade, co-founder of the at that time lived in Cambridge. available on the TNMOC website Computer Conservation Society Earlier Dr Clark had bought three www.tnmoc.org, and the Museum’s said: “EDSAC provided, for the first or four EDSAC racks intending to social media accounts. Matt will talk time, reliable computing capability convert them into bookshelves. The about the project at TNMOC on for scientists. It could be said that other chassis were later discarded, Thursday 16th April 2015 at 7.30pm. EDSAC invented the user as a although some may have been See www.ticketsource.co.uk/tnmoc distinct class of practitioner.” given to colleagues. to secure your place. TNMOC newsletter 4 Q1 2015 team of ‘FUZEliers’ isitors to The National eteran Colossus operators are sponsored by FUZE Museum of Computing were delighted with the recognition A Technologies is ready every V able to join the largest V of Colossus, the world’s first weekend to welcome young and learning event in history during electronic computer, and its designer budding computer programmers at Code Week last December and Tommy Flowers, in the latest set of TNMOC to show them how to gain hands-on coding experience at stamps issued by Royal Mail. The code using the FUZE platform to the home of Colossus. Inventive Britain stamp set explore the huge potential of celebrates eight key inventions of the computing. The Hour of Code in Code Week past century in disciplines and was a global movement reaching applications ranging from materials The FUZEliers introduce young tens of millions of students in more to medicine. One of the two first- coders to the FUZE, a purpose- than 180 countries. class stamps in the series celebrates built, computer to make teaching During Code Week, every school Tommy Flowers’ creation of and learning programming easy Colossus. and fun. Powered by a Raspberry visiting TNMOC took part in a Pi it is programmed using the coding session in the Museum Two of the very first users of popular BASIC language. classroom. Youngsters could join in Colossus Mk I were delighted with Codability sessions and adults the news. Any young visitor can drop in and were able to work through sample be guided by a team of student programs or do some coding Irene Dixon said “I’m absolutely FUZEliers. No previous themselves in the Museum’s thrilled that Royal Mail is recognising experience is necessary. Software Gallery. the achievement of Tommy Flowers which was kept secret for so long. In FUZE is very popular with school As a Museum of computing and not December 1943, I was 19 when I groups that visit TNMOC. Tim just computers, TNMOC is keen to arrived at Bletchley wondering what Reynolds said: “Because of its get people interacting with historic my secret duties would be. For the robustness and simplicity, FUZE is and modern machines wherever next 18 months I was a Colossus very suited for use in public possible. Visitors can acquaint operator although I dared not speak environments such as this themselves with the amazing freely of this until 1995 when I visited Museum and schools. We like to history of computers … and get Tony Sale.” start kids coding here and coding. encourage them to continue what Betty O’Connell, who worked they have learned at home. In the Every weekend, youngsters can alongside Irene Dixon, said: “It is past, parents have even asked take part in Weekend Codability such a shame that Tommy Flowers’ where they can buy a BBC Micro – sponsored by Ocado Technology’s achievement has been now we can point them to FUZE, Code for Life initiative overshadowed because of the available from the TNMOC shop. (www.codeforlife.education) and secrecy around Colossus for so receive introductory – often their many decades. If Tony Sale hadn’t “The FUZE is a direct descendant first – guidance in computer been so determined in reconstructing of the 1980’s BBC Micro and programming from a team of Colossus, I don’t think anyone would provides a very valuable tool in specially recruited student guides. know that there were two major explaining to youngsters the These young coders learn how to ciphers broken at Bletchley Park.” development and potential future modify programs and create their for computing.” own. Information leaflets enable Kenneth Flowers, Tommy’s son, also them to continue developing their greeted the news warmly: "My father FUZE Technologies Ltd, created would be delighted with the the computer to help schools meet skills afterwards at home, school or in a coding club. recognition of Colossus on a first elements of the National class stamp. I also know that he Curriculum. See www.fuze.co.uk would have made it very clear that for more about FUZE. Colossus was a team effort." TNMOC newsletter Q1 2015 5 Tony Sale award for conservation
Z1 Architecture and Algorithms, the other joint-winner, is a virtual reconstruction of one of the world’s earliest computers, the Z1. Originally built in 1936-1938, the Z1 was destroyed in a bombing raid in 1943. In the 1980s and then in his 70s, Konrad Zuse embarked on a reconstruction of the Z1 which is now a remarkable but static exhibit at the Technology Museum in Berlin. However, with 30,000 parts the reconstruction of the mechanical computer was unlikely to be robust or reliable enough for regular operation, so a team led by Robert B Garner and Professor Raúl Rojas Professor Raúl Rojas began a virtual reconstruction.
he 2014 Tony Sale Award for Museum of Computing on Bletchley Through the meticulous research of computer conservation has Park.” Professor Rojas, a team of his T been jointly awarded to two students was able to construct a 3D The IBM 1401 Demo Lab is a outstanding and contrasting entries visual simulation of the arithmetic classic reconstruction of a 50-year representing computing in the 1930s unit for deployment on the web. In old commercial computer. It and the late 1950s. addition, hundreds of high resolution marked the transition of IBM as a photos of the Z1 enable web users The winners are the IBM 1401 Demo supplier of accounting machines to to explore the machine from any Lab, a restoration of one of the most it becoming the dominant supplier angle at very high resolution. See significant machines in computer of the mainframe era. Announced http://zuse-z1.zib.de/ for the virtual history by the Computer History in 1959, the IBM 1401’s success reconstruction. Museum in California, and Z1 took everyone by surprise. The Architecture and Algorithms, a virtual company had expected to sell or The judging panel said “Z1 reconstruction of the 1930’s Konrad lease about 1,000, but went on to Architecture and Algorithms is a Zuse mechanical computer, by the deliver 15,000 and by the mid- remarkable vision of how such Free University of Berlin. 1960s they amounted to half of the complex artefacts might be delivered computers in the world. Its high- to a worldwide audience. It is a Run by the Computer Conservation speed chain printer was a key to its project that will undoubtedly give Society and sponsored by Google success -- punched card machines museum curators pause for UK, this is the second Tony Sale were eagerly traded in for the IBM thought.” Award for computer conservation. 1401 and business computing took Rachel Burnett, Chair of the CCS, In announcing the 2014 winners, a huge stride forward. said “The late Tony Sale would have Martin Campbell-Kelly, computer In a project involving 20 volunteers been delighted with the entries that historian and head of the judging over ten years, two 1401s have we have had in the year of the silver panel, said: “The eight excellent been restored at the Computer jubilee of our Society that he co- entries for the 2014 Tony Sale History Museum in Mountain View, founded with Doron Swade. Award from four different countries California. The computers and clearly demonstrates how computer ancillary equipment are regularly “The computer conservation conservation is flourishing more than demonstrated for visitors. See movement is dynamic and growing 20 years after Tony Sale embarked http://www.computerhistory.org/ apace. We salute the computing on his pioneering and awe-inspiring atchm/restoring-the-ibm-1401/ for pioneers of the past and the rebuild of a Colossus Mk II, a world- more information about the project. dedication of those who breathe life famous exhibit at The National into our computing heritage.”
TNMOC newsletter 6 Q1 2015 EMF
things too loud, I retreated to ‘The Robot Arms’ for a pint. I met a man with a giant ride-in rubber duck. I later witnessed a race between said giant duck and the BigTrak. A late-entry Sinclair C5 won. I tried my hand at Morse code (rubbish) and made a virtual-reality headset using a piece of cardboard and my phone. My son made a stop- motion animation and my wife successfully picked a 4-lever lock. We ooo-ed at the retro arcade complete with classic consoles and pinball, then ahhh-ed at the laser- cutters opposite.
TNMOC’s PJ Evans giving a talk on Tunny and Colossus at EMF Even your conference badge was a thing of beauty. Not for us the humble piece of paper. This was an nce every couple of years, a provided mains supplies, network Arduino-compatible circuit board campsite appears Brigadoon hubs and Wi-Fi hotspots. with attached battery and LCD O -like in Buckinghamshire. screen. A radio receiver was Over the course of three days nearly A simple joy of EMF are the capable of receiving updates from one thousand people converge there surprises. At every turn we saw the organisers which would then be to show, tell and learn just about any something we had never seen displayed on screen. It even had subject, from coding to lock-picking before. These sights included, but Tetris. Best of all, it was yours to or radio communications to forging were not limited to, a robot- keep and the EMF web site has all your own ‘one ring’. Electromagnetic controlled cocktail machine that the information on how to bend it to Field has it all. would make your favourite tipple by your will. rushing back and forward along a This year, Electromagnetic Field (or set of optics, a life-size BigTrak, a Obviously many of the attendees of EMF to attendees) took place just a Russian communications truck, an such an event would be interested in few minutes from The National interactive space adventure made what The National Museum of Museum of Computing on the out of an old caravan and a Computing had to offer and that was outskirts of Bletchley. This has spinning music machine that exactly why I was there. On become a centrepiece event for the changed its melody based on your Saturday evening I gave a talk in the ‘Maker’ movement, those fascinated number and proximity to it. Oh, and main tent of the story of Tunny & by the act of creating from raw quadcopter drones everywhere. Colossus. I also had the honour of materials. There are also geeks like being the support act to the me, computer and electronic The daytime was spent either journalist and author Simon Singh, enthusiasts who tend to ask ‘why browsing the many ‘villages’ where who brought his very own Enigma not?’ much more often than ‘why?’ local Maker groups demonstrate machine. when considering their next project. their creations, happily answering questions or letting you ‘have a go’. EMF is exceptionally family-friendly We arrived early on Friday and Alternatively, you could attend one to the point of having a dedicated headed for the quiet area. Once of the numerous talks and hands- childcare facility that also had its pitched it was time to go exploring. on construction opportunities. own workshops. One rule that both Mind you, pitching a tent at EMF is events have in common is ‘no quite unique. Within one hour of In the evenings, talks continued spectators’. Turn up and participate. arriving, we not only had our tent until the music kicked in. Being Bring something, make something or ready but also an extension lead EMF, a simple DJ set was never simply just volunteer to help with the straight into the tent for mains going to cut the mustard. Enter the enormous logistical exercise electricity and the best public Wi-Fi ‘live coders’, who composed music involved in dumping hundreds of I’ve ever experienced. You could on-the-fly using a dedicated people in a field. It was a magical also have hardwired Ethernet to the programming language that was few days and I’m already making tent if you wished. All of this continuously edited to change the plans for 2016. courtesy of the many portaloos output. Another attendee brought a dotted around the camp that selection of lasers that he ‘played’ https://www.emfcamp.org/ live along with the music. Finding TNMOC newsletter Q1 2015 7 Transputer Project
omputer rebuilding, networking and standard RS-232 language and compiler. It was not reconstruction and restoration serial ports. until 1985 that the first prototype C are key aspects of the Transputers came off the production activities at TNMOC. The museum Amongst other influences, line at the Inmos foundry at volunteers have engaged in a evolutions of the transputer link Newport, Gwent. number of important projects to technology have been promoted by preserve the important history of 4Links in SpaceWire technology How Transputers work computing, in particular, British that is being designed into more Transputers work by sending computing. Projects have included than 100 satellites. 4Links is based programs and data down Transputer the world-famous Colossus, Heath on Bletchley Park and is a keen links to each other. These links are Robinson, Harwell Dekatron supporter of TNMOC used by programs to share data and create work structures, for example, (WITCH), EDSAC, ICL 2966, Elliot History of the Transputer 803 and many other systems that pipelines. The Transputer was a product of were key to the developments in Inmos Ltd, a British semiconductor A pipeline is analogous to a computing. company based in Bristol and production line. For example, take A recent project embarked on by Colorado Springs, USA. Inmos was the task of building a wall clock: TNMOC volunteers is to restore two founded in 1978 by Iann Barron the first person cuts out a Inmos Transputer Development and Dick Petritz. Iann Barron had chassis System units. Later they plan to previously managed CTL restore a large system originally (Computer Technology Limited) the second worker paints the used at CERN. The Transputer that produced the Modular-One chassis device was a novel parallel computer. Dick Petritz ex Texas the third worker adds the clock processing device from the 1980s. Instruments and one of the face Although the CPUs are no longer founders of Mostek (Z80 fame). the fourth worker adds the produced, they have been influential The rationale behind the design of mechanism in improving computing speeds with the Transputer came from the point the fifth worker packages the techniques beyond simply -to-point connection architecture of finished clock ready for increasing clock speeds and silicon the Modular-One computer and the dispatch. real-estate integration. work of Tony Hoare (of QuickSort At each tick, one new wall clock is What is it? fame) on Communication between produced from the production line. The Inmos Transputer was a British- Serial Processes (CSP). His seminal paper led to the design of Alternatively, five workers could designed, parallel microprocessor produce one finished wall clock architecture from the early 1980s. the Transputer and the parallel programming language Occam by each, in more-or-less five ticks, by The Transputer was unique in that David May. sharing resources and scheduling each processor had a built-in simple their use. operating system, memory and four The Inmos business plan had the intention to generate substantial The design of the parallel high speed (20 Mbit/s full duplex) bi- architecture of the software and directional serial links. The early revenue from large capacity, high-speed static RAM and use that computer depends on the problem Transputer is essentially a computer needing to be solved. The system on a chip. The links on the money to fund the design and manufacture of a radical new Transputer is unique in that adding Transputer allow connection to up to more Transputers can significantly four other Transputers or microprocessor. Starting in early 1981 David May designed the increase the system power without peripherals such as video graphics, impacting performance. floppy and hard disc drives, Ethernet Transputer and the novel Occam
TNMOC newsletter 8 Q1 2015 So what happened? Project aims David May, one of the architects of Production delays, cash starvation, The Transputer Restoration Project the Transputer: high selling price and poor uptake of aims to bring into service and https://www.cs.bris.ac.uk/~dave/ the Transputer conspired to spell its maintain two fully functioning Inmos transputer.html doom. Without money, the compilers Transputer Development System for high level languages such as units. The first unit contains 64 What David May is doing now: PROLOG, LISP, C, FORTRAN, ADA processors and runs a http://www.xmos.com/ etc were not produced until much demonstration of parallel later. processing of this 1980's Tony Hoare, the man behind CSP, technology using a Mandelbrot Set Without the compilers, programmers the logic behind the Occam generator and a Ray Tracing language built specifically for the showed little interest in the simulation. architecture. Transputer: Secondly, a system containing two http://en.wikipedia.org/wiki/ The touted benefits of parallel banks of 12 processors with Tony_Hoare processing to overcome the dedicated video cards and monitors apparent ceiling of computational to drive a dual flight simulator. An article about CSP: power inherent of 1980's http://en.wikipedia.org/wiki/ microprocessor design were dashed A longer term project is to restore a Communicating_sequential_process as new microprocessor design large system based around a es techniques overcame these network of 100 T9000 Transputers performance obstacles. Wavering that were originally used for fast Companies who produced programmers were then persuaded data capture at CERN. Transputer based systems to continue using their well-known More details on the project can be Parsytec - produced huge and understood toolsets on supercomputing arrays of microprocessors such as the Intel found at: http://www.tnmoc.org/special- Transputers some containing over 80x86 (PC) and Motorola 680x0 16,000 and weighing over 1 ton: (Atari ST/Falcon, Commodore projects/transputer Amiga, Apple Macs and Sinclair QL). http://en.wikipedia.org/wiki/Parsytec Further reading Inmos changed hands many times The inspiration for the project: Meiko Scientific Ltd - produced before ending up in the ownership of http://www.tnmoc.org/news/news- supercomputers, notably the SGS Thompson (now ST releases/new-company-donor- Computing Surface-1 that initially Microelectronics). glimpses-its-own-history-tnmoc used networks of Transputers: http://en.wikipedia.org/wiki/ Meiko_Scientific
Floating Point Systems Inc - produced, the T-Series Tesseract Transputer supercomputer: http://en.wikipedia.org/wiki/ Floating_Point_Systems
Simplified view of how the Transputer development system on show at the museum Transputer devices are connected TNMOC newsletter Q1 2015 9 DIY CPU
Mnemonic Opcode Binary Hex Uses representation representation memory?
JMP Jump 00 00 0000 00 n/a JPC jump on carry set 00 00 1110 0E n/a JPZ jump on zero set 00 00 1011 0B n/a JNC jump on not carry 00 00 1101 0D n/a JNZ jump on not zero 00 00 0111 07 n/a JPE jump on C or Z 00 00 1010 0A n/a NOP jump never 00 00 1111 0F n/a DO Don't jump, but set RAR 00 11 1111 3F n/a Setting bits 21,20 (0x becomes 3x) sets the RAR before any operation
DEC decrement acc 01 00 0000 40 no SUC (acc minus mem) -1 01 00 0110 46 yes ADD acc plus mem 01 00 1001 49 yes ASL shift up 01 00 1100 4C no NOF Like NOP, but it conditions Z, C 01 00 1111 4F no INV complement acc. 01 01 0000 50 no NAN (not acc) AND with mem 01 01 0001 51 yes SET load acc. with FFFF 01 01 0011 53 no LDC load acc with complement of mem 01 01 0101 55 yes XOR acc XOR mem 01 01 1001 59 yes LDA load accumulator from mem 01 01 1010 5A yes IOR acc OR mem 01 01 1011 5B yes CLR zero accumulator 01 01 1100 5C no AND acc AND mem 01 01 1110 5E yes SUB acc minus mem 01 10 0110 66 yes ADI acc plus mem plus 1 01 10 1001 69 yes SFI shift up, setting LSB to 1 01 10 1100 6C no INC add 1 to Acc 01 10 1111 6F no (All ‘01xx’ ALU operations condition the carry and zero flags) STA Store acc to memory (every STA 10 00 0000 80 yes instruction writes to main memory AND to the auxiliary field at the same time. This auxiliary field is used to contain "important" output ports and probably the write locations of CPU registers) STO Store acc to memory and output 10 00 ssss 8s yes 'ssss' field selects 1 of 15 ancillary registers Valid ssss : (81 to 8F) in a simultaneous write 0001 to 1111
TNMOC newsletter 10 Q1 2015 n the last issue of InSync, we looked at a homebrew guess) then 16-bit arithmetic constants can be safely CPU designed by TNMOC member Myk Dormer, stored in the unused fields of other op-codes. I concentrating on the hardware aspects of the design and the register level controls. This time Myk focuses (This method will clearly require careful record keeping, on the programming aspects of this system. but will reduce the amount of memory space required by the code). Memory Map: 0000 reset vector Indexed mode: It would appear that the 2416 processor doesn't support any form of indirect addressing. A 0000-7FFF RAM cursory examination of the op-code set and the design will reveal only an absolute address mode (16-bit 8000-FEFF expansion RAM (or ROM) address embedded in the op-code). However the design supports the (very necessary) index or pointer FF00-FFFF I/O page addressing mode in one of two ways:
FF00 (unused) 1) Self modifying code. Although a heresy to modern software design concepts, a pointer can be FF01 parallel input port (16 bits wide, implemented very easily by writing the pointer value, high byte reads 00) combined with the desired (LDA, STA) op-code, to a memory location and then executing it. FF02-FFFE (unused)
FFFF RAR register (read only, A pointer read code fragment: executable) Imagine the pointer value is kept at 000F and 0100 Ancillary registers ssss = contains the constant '5A0000' (the op-code for LDA). The code starts at 0200: 0000 do not use 0200 LDA 0100 ; take the op-code for “LDA” 0001 parallel output port (lowest 16 bits) 0201 IOR 000F ; IOR it with the (16 bit) pointer value 0010 to 1111 unused (tba) 0202 TA 0203 ; put it into location 0203 All instructions have the same timing: one op-code fetch, followed by one memory access cycle (even if an 0203 (LDA xxxx) ; execute a read of the location in the pointer individual instruction doesn't need the second part of the process). 0204 ; code continues with the result in the accumulator The image on the left depicts the op-code set. All of the instructions consist of an 8 bit op-code and a 16 bit address field (which is usually, but not always, the This technique will only work if the code is running in memory address of the second access cycle). Most RAM (if running code in ROM it is necessary to first operations are accumulator store or load functions. The write the small subroutine to RAM and then execute it 8 bit op-code in turn consists of a two bit ‘true’ op-code there) and is obviously not re-locatable (I plan to write a (selecting ‘read from memory to accumulator via ALU’, slightly cleverer than usual assembler to deal with such ‘write accumulator to memory’ or ‘some variety of jump’) problems). followed by a six bit ancillary field (which selects ALU function, carry state, return address functions, etc.). 2) Mapped registers. A closer inspection of the bus specification will reveal a control line called INH. This Loading constants. There are no ‘immediate load’ controls the assertion of the lower order 16 bits of the operations. Instead there is a simple programming ‘get- instruction latch (the address operand) being asserted round’. Any constants used by a program are loaded to onto the address bus. It is usually linked to the execute main memory, along with the executable code. They cycle clock, but, if it is driven by suitable logic, it would are then simply read by ordinary memory access allow hardware external to the main CPU to take control instructions. (Don't overwrite them by accident!) of the address bus during the execution of an instruction and replace the absolute address with something else. A further short-cut can be seen in the structure of the op-codes. Many commonly used instructions make no Practically, this would take the form of a location in use of the 16-bit address field. Providing that no use is memory which, when accessed by a load or store being made of the upper (op-code) byte later (and with instruction, causes the address used by that instruction all I/O devices being 8- or 16-bits wide, this is a fair to be replaced with a value stored in an ‘index register’.
TNMOC newsletter Q1 2015 11 So, for example, address FFFE might be defined as the routine is needed, then either a full software stack is ‘index location’, so the instruction LDA FFFE would implemented or the value of RAR is written into the actually execute as LDA (contents of index register). location of the routine's return jump (More self-modifying code: a nightmare indeed!) In hardware terms, all that is required is: Shift operations: In its basic form, the only shift a. An address decoder which looks at the lowest operation that this CPU can execute is a shift up one bit 16 bits of the instruction latch (not the address (by doing an ‘add accumulator to itself’ instruction in the bus), decodes the address associated with an 74181). indexed operation (in our example above this would be FFFE) and provides suitable logic to This will make divide operations and byte packing / drive the INH line. unpacking very clumsy so I think that in the future we will need an external shifter unit, mapped into the I/O b. A 16-bit register with outputs that drive the page at Ffxx along with all the other ‘extensions’. It will address bus, activated by the instruction also be necessary to implement ‘byte swap’ hardware to decoder mentioned above. This could be a allow the upper 8 bits of the data bus to be manipulated single register or it could be a small bank of fast through the 16 bit ALU. RAM, for multiple index pointers. Reset: At reset, execution will commence at location How data is written into the index register is open to a 0000. There are no interrupts or other forms of reset at number of choices. The register could be mapped into present. It may be necessary to introduce something memory at another memory location (this is the method later. In addition, there may be timers and a watchdog used by the PIC micro), either write only or (more system, but these will be peripherals, rather than being conveniently) as a read/write location. It could be part of the CPU. arranged for a specific op-code (either a write to a dummy location or a special (11xx code) op-code) to Communicating with the outside world: The current transfer either an immediate value or the contents of the implementation has only a simple parallel I/O port, a few Acc. Initial thoughts were to map it to a memory indicator lights and a front-panel system (functional address such as FFFD. when the unit is in the reset state) comprising of switches (to set data/address values), lights (to monitor A pointer read, using hardware index register: the same) and simple hardware to manually generate write cycles. This requires all code to be entered Initial Pointer value is stored at 000F manually, one 24-bit binary word at a time, by hand before anything can be done with the hardware. Code starts at 0200 While this is acceptable for initial proof of concept 0200 LDA 000F ; take the desired pointer value demonstrations, anything beyond a dozen instructions 0201 STA FFFD ; put it into the index register becomes very onerous and the code entered is lost at switch off, as there is no ‘backup store’ in the design. 0202 LDA FFFE ; execute an indirect read In the future I will need to expand the system in one of 0203 ...... ; code continues with the result in Acc two ways:
a. Including some pre-programmed ROM in the Imagine the pointer register is mapped to FFFD and the memory-map, containing (at least) a indexed mode substitution address is FFFE. rudimentary monitor or loader program and another port (such as an RS232) so it can Subroutine jumps: This architecture provides no communicate with a ‘user console’ (probably a hardware stack (in its basic form at least) and has no PC pretending to be a teletype or my ancient dedicated ‘call’ or ‘return’ operations. Instead, another ASR33 if it still works), or memory mapped ‘return address’ register (RAR, at location FFFF) is used. This register stores the location b. Devising a hardware loader to write useful code following the last executed jump (or other) operation if into RAM at start up (some form of simple state bits 21 and 20 of the relevant instruction are both set to machine, reading data in from an external 1. device that emulates (or actually is) a card or paper tape reader. The most significant byte of this register is hard-wired to the jump op-code (00) so the location can be directly Even when an I/O facility is available, there is still the executed. A non-nested subroutine can simply jump to problem of getting a byte wide world to talk to the 2416 the RAR register location (and execute it). If a nested CPU’s 24-bit bus. As the hardware currently stands,
TNMOC newsletter 12 Q1 2015 there is no simple way that a low order byte (read in implementing a true secondary store using a hard drive from a UART for example) can be written to the highest or magnetic tape unit. 8 bits of a 24-bit memory location or for that location's highest byte to be transferred into lower order memory. Do I keep the CPU itself in its original, simple state or do I expand the hardware to include hardware stack(s), This will require further hardware, most probably a index pointer registers, timers, real time clocks, simple I/O port, cross connected to shift down by 8 bits interrupts or even expanded the op-code set (via the (write 'aaaaaaaabbbbbbbbcccccccc' , read back unused 11xxxxxx codes)? 'ccccccccaaaaaaaabbbbbbbb' ). It should be possible to re-use much of the design of the existing I/O card to Finally there is the question of software: I plan to write implement this function. at least a simple loader/ monitor/ operating system on the 2416 itself and will probably implement a cross- Future progression: assembler or simulator on a PC, but from there on I'm unsure. Do I write further high-level functions myself (a In its current form, the 2416 is a functional, Turing- BASIC interpreter would be interesting) or do I try to complete processor, capable of simple arithmetic or port something like Linux? logical operations, but it is highly limited by its 1950 style ‘switches and lights’ interface. I think I may be busy for some time.:
I have already detailed the next stage of the The latest update from Myk is that he has nearly development (provision of some method of loading data completed an autoboot diode ROM board. “Not the most into the RAM without using the manual-driven interface) difficult layout I've ever done, but definitely the most and when that is complete then the processor will be far boring”: 22 words x 24 bits wide, 550 diodes (528 "bits" more usable … but what comes next? plus 22 "logic" diodes). It maps to the top 22 locations in the last 32 word page in the FFxx I/O field (FFE0 to More sophisticated I/O, with at least a serial link to a FFF6). terminal (or terminal emulator). Possibly extra parallel and/or analogue I/O (to make the unit more useful for Additionally, Steven Taylor is building a compiler for the ‘on the lab bench’ control jobs), maybe even eventually CPU. adding a video display (bringing the user interface into the 1970s). You can find all the details on Myk’s ambitious project by visiting his Facebook site: Backup store of some kind will be essential for any serious usage, but I am undecided on keeping with slow https://www.facebook.com/groups/553432921406179/ serial port connected (simulated) paper tape or
Control signals: The operation of a processor is controlled by a whole host of strobes and clocks. Some are familiar to anyone used to microprocessor buses: Address bus 16 bits. Inverted (logic 1 = 0V) with pull-ups to 5v
Data bus 24 bits. Inverted (logic 1 = 0V) with pull-ups to 5v n_RD Read (active low) (assert memory or I/O contents to data bus) n_WR Write (active low) (clock register contents into memory or I/O location)
n_RST system reset, active low, with pull-up to 5v (tri-states bus signals above)
n_FE Fetch. Assert bus signals during the fetch cycle (active low). Also clocks the PC
n_EX Execute. Assert bus signals during the execute cycle (active low)
clk_I active high pulse (62nS) latches fetch cycle memory read into instruction register
clk_A active low pulse (62nS) latching ALU result to ACC. This occurs towards the end of the execute phase clk_B active low pulse (62nS) latches execute cycle ram read into the ALU temp register
Carry carry bit output of ALU Zero zero bit output of ALU INH If low, asserts the IL onto the bus. It is usually tied to the n_EX signal
TNMOC newsletter Q1 2015 13 Screen invaders
n the 1960s the so-called British game development right up to the become a world leader in producing Invasion transformed pop music dawn of the 1980s. games for home computers. Ithrough the Beatles, the Stones Hobbyists dominated and odd-ball Meanwhile, the low-cost home and lots more. In the 1980s, the games thrived: Fat Worm Blows a computer boom of 1980’s Britain British did the same with computer Sparky, Frak, Head Over Heels, games and today the UK is the provided a training ground for Revenge of the Mutant Camels, world's second largest consumer of would-be British games makers. In Deus Ex Machina. video games and the fifth biggest particular the sub-£100 Sinclair ZX80 provided a spark to growth, producer. British inventiveness and followed of course by the BBC experimentation rippled out to other In the Thursday lecture series at Micro and others. Suddenly you countries in a way that echoed the TNMOC, Tristan Donovan traced the were more likely to find a computer British Pop Invasion of the 1960s. quirky history of Britain's fascination in a British home than in an Other countries started making with video computer games. American home, a situation that games for the UK market and British persisted into the 1990s. However, games makers were asked to work Britain was one of the first to software was thin on the ground, for large companies like Nintendo. conceive of computer games. Alan so enthusiasts took to writing their Even today you are likely to find Turing dreamt up TurboChamp own programs and games were a creative British games developers in computer chess in 1948 although it natural draw. the large US games makers. was some years before it was implemented. Nimrod displayed at In post-punk, recession-hit Britain, Tristan Donovan's book Replay: The the Festival of Britain in 1951 was cottage industry was to the fore History of Video Games gives the the first computer game to be played and with it came a lot of inspired full story. by the public, and Noughts and quirkiness. With so many unusual Crosses soon appeared on EDSAC. British-made machines to cater for, Don't miss other fascinating talks in the US producers showed little the TNMOC Lecture Series. Sign-up But then all went quiet in the UK and interest in competing with the UK for early notification of lectures: just it was left to the US to create the game makers and Britain started to email [email protected] with Lectures games industry and lead the way on as the subject line. TNMOC newsletter 14 Q1 2015 Peter Wescombe 1932—2014
eter John Wescombe was born in Eltham, Kent in 1932. When he was twelve, during WW2, his P mother suddenly, and out of character, said “let’s go for a walk” – while they were out a V2 rocket demolished their house. From necessity, at the age of fourteen he joined the four- mast ship TS Arethusa, a Shaftesbury Home Training Ship for boys aged between 12 and 16, where discipline was tough and life Spartan. The boys remained barefoot on board ship even in snow and they had to climb the 175 foot masts each morning before breakfast. At 16 he was able to join the Ganges as a Boy Telegrapher. In 1951 he was on HMS Belfast during the Korean War. On returning to the UK in 1953 he married Rowena and when his time in the Navy finished in 1957, the Essex Police Force offered them some stability. This only lasted until 1960 when the lure of foreign travel presented itself with an advertisement in The Daily Telegraph for the Diplomatic Wireless Service (DWS). The following thirty years was full of excitement, from jackals under the house in New Delhi, India; archaeological exploration with Lorraine Copeland, (wife of Miles Copeland, one of the founders of the CIA) and the publishing of their book An Inventory of Stone Age sites in Lebanon – still a standard guide to archaeology in the region; Djakarta where he and his family faced the choice of being drowned when a reservoir overflowed their house or being shot in the streets for breaking curfew (in the end the reservoir remained stable). Singapore followed, then Baghdad where he indulged his great passion for biblical archaeology. This tour was cut short when he was Persona non grata-ed from Iraq by Saddam Hussein’s government in a diplomatic tit-for-tat.
Somalia followed. Then the Soviet Union at the height of Executives. Peter also lectured abroad in America; the Cold War, where Peter was greeted on post by the he studied the Australian wartime archive, then shooting down of Korean Airliner KAL 007 and saw the moved to Bletchley Park’s Archives. He produced deaths of the last three Soviet presidents, Brezhnev, several useful booklets which sold well. He was a Andropov and Chernenko. stalwart; had it not been for him, the Park would now be a housing estate. His last post was South Africa during the final days of apartheid. He was admirably supported during his career by his wife Rowena with whom he had four children – As his career in the DWS drew toward its close, he Carlita, Katy, Jeremy and Justin. became concerned about the future of Bletchley Park, which he knew had been involved in the breaking of Axis We offer our sympathy to his family, but they have codes and cyphers during the 1939-1945 war. He and the satisfaction, as we do, of having known Rowena began the Bletchley Park restoration process in someone whose gifts were given full rein in his 1991 but were not allowed to join the campaign until he career and who left a little mark on history. had retired. The Bletchley Archaeological & Historical Society involved Milton Keynes Council, the Science TNMOC would like to thank Peter’s daughter, Kate Museum and other bodies so that the Park was indeed and Dr Peter Jarvis, Bletchley Park volunteer guide preserved. After various adventures it now seems secure for providing the obituary. Photo of Peter holding an for the future. Peter was a Trustee for a while, but M209 machine provided courtesy of John resigned over the style and activities of senior Alexander. The M209 was a small, light-weight management about which (as usual) he made the portable, hand-operated mechanical cipher strongest possible criticism. However, he did continue as machine, developed by Hagelin in Sweden for the a Tour Guide through a couple changes of Chief US Army.
TNMOC newsletter Q1 2015 15 Events
Spring Lectures: For more information and tickets visit: Computers in Entertainment http://www.tnmoc.org/news/upcoming-events/computers Rob Halliday -entertainment-talk-rob-halliday Thursday 12 March 2015 7.30pm
In this talk, Rob Halliday will look at how computers Easter Bytes 2015 is on its way! moved into entertainment lighting, from pioneering systems such as Strand's IDM up to the remarkable Digital fun and games for all the family Lightboard created for the National Theatre, which still 1 - 12 April, every day from 12 noon to 5pm has some tricks that the current generation of PC-based control systems in use today can't replicate. Among some of the most amazing machines telling the story of our digital age, you'll find: The Imitation Archive: Field Recording in the Digital Age LEGO - robots! Matt Parker Minecraft Thursday 16 April 2015 7.30pm Codability to introduce youngsters to coding The first rule of listening according to the pioneering soundscape composer R Murray Shafer is “if you can't FUZEliers to help you control robots hear it, be suspicious”. Sound recordist and composer Matt Parker will discuss the process and techniques of and retro computer games, games, games ... high fidelity digital field recording and will explain how sound can help us understand our evolving cultural Watch this page for details as they emerge: landscape. http://www.tnmoc.org/bytes Matt's talk will include live demonstrations and a Another fun premiere of some of his recently produced compositions packed bytes made from recordings taken at The National Computing festival Museum for the Imitation Archive project. sponsored by:
Museum Locator he articles in this newsletter Harwell Dekatron (‘WITCH’) reference several of the exhibitions T within TNMOC. This plan will help you locate the specific exhibits. EDSAC Bytes events & Codability classroom Alternatively, if you own an iPhone, iPad or iPod device, you could download the TNMOC app from the Apple iTunes app Transputer store. The display app provides additional information about the galleries Museum Entrance and other information to help you The Tunny make the story entrance most of your visit to the Museum museum. Exit Café & Just search shop for TNMOC in the Colossus iTunes store. TNMOC newsletter The National Museum of Computing is the operating name of Codes and Ciphers Heritage Trust, charity number 1109874 16 Q1 2015