Chapter 31

NuBus, PCI, and Other Slots

IN THIS CHAPTER: What NuBus is What PDS means What PCI does How to install a card The future of slots

Installing new circuit boards into your Mac has always been a breeze. On the Windows machines of yesteryear, you’d have to fiddle around with a bunch of little jumper plugs and DIP switches. On the Mac, you just insert the board in the slot, reboot your Mac, and you’re in business. Although sometimes you may have to install a control panel to make some settings to the board, a NuBus or PCI device is self-configuring. But that easy setup process belies the sophisticated technology behind it.

NUBUS CARDS The expansion slot standard used on Macs until late 1995 is called NuBus (pronounced new , which, more or less, describes what it is). The technol- ogy was originally developed in the 1970s at the laboratories of MIT and was perfected by for use in computers. Apple’s version of NuBus wasn’t released until March 1987, when the II

1003 1004 Part IV: Attachments

CASE HISTORY was produced. The Mac II (and its successors, the IIx and GETTING THE SIZE RIGHT IIfx) contained six expansion slots; no model since then has had as many. There was a bit of a flap back in 1987 when Apple went to the Institute of Electrical and The big idea Electronics Engineers (IEEE) to get their version of the NuBus The theory behind NuBus is simple: It’s a bus (an elec- specification certified. tronic pathway) that lets you expand your Macintosh. Apparently,Apple’s engineers Without having to buy a new computer, you can add fea- failed to account for the tures as you need them. thickness of the Mac II’s case By far the most common NuBus card is a video display when they made their adapter board (see Chapter 11 for more on monitors), measurements from the blueprints.Consequently,when into which you can plug your monitor. While most they started testing prototype recent Mac models have built-in video memory, most NuBus boards,they found that still require a video board if you want to get 24-bit color the boards built to this spec or graphics acceleration. were a quarter inch too big to fit Some other reasons you might buy a NuBus card: in a Mac! To provide or Token Ring network commu- Needless to say,Apple was nications capabilities to a Mac that doesn’t have forced to contact the IEEE and them. have the standard changed slightly before it was published. To speed up SCSI transfers (see Chapter 30 for details on SCSI-2). To capture video images, either still frames or movies, for processing on your Macintosh. To replace some of the functions of your Mac’s main logic board in the pursuit of accelerating your Mac. To put a PC inside your Mac so that you can run DOS and Windows pro- grams without buying a whole new computer.

NuBus ’90 In 1990, the Institute of Electrical and Electronics Engineers (IEEE) overhauled the NuBus technological specs. They arrived at a new design, called NuBus ’90, which Apple implemented either partly (Quadra family, for example) or com- pletely (Quadra 900/950 and first-generation PowerPC-based Macs). The differences between NuBus and NuBus ’90 are extremely technical, but they boil down to speed. A feature called the IIx Block Transfer Protocol doubles the speed of information flowing between the Mac and the card (to 20 MHz from the previous 10 MHz). Chapter 31: NuBus, PCI, and Other Slots 1005

PDS CARDS Certain Mac models — such as the LC series — have a Processor-Direct Slot (PDS) instead of a NuBus slot. The PDS is another way of expanding your Mac’s capabilities. A card installed in this slot hooks directly to your Mac’s main logic board; the PDS board becomes, in effect, a part of that logic board. (A NuBus board, on the other hand, can be a computer unto itself.) A PDS card is ideal for less ambitious hardware add-ons, such as cache boards and accelerators. Unlike the NuBus board, which can work in most any Mac with slots, the PDS board has to be designed to support a specific model or range of models. (There are, however, adapters that let you plug NuBus cards into some PDS slots.)

THE PCI REVOLUTION NuBus is on its way out. Beginning with the late-1995 Power Mac models, Apple introduced a new expansion-card technology to the Mac. It’s called the Peripheral Component Interconnect (PCI) Local Bus. More than 150 other com- panies, too, have endorsed this new technology. All future desktop Macs — and even PowerBooks — will feature PCI slots instead of NuBus. In some ways, PCI and NuBus are very similar: Visually, for example, there’s not much difference. Where a NuBus card has a plastic connecting plug at the bottom, the PCI board’s “pins” are etched into the bottom edge of the board itself. Installation is simply a matter of sliding the board securely into its slot. Likewise, PCI cards perform much the same jobs as NuBus cards — such as adding high-speed networking, accelerated video display, video digitizing, high-speed SCSI data transfer, or DOS/Windows capability to your Mac. In other ways, however, PCI and NuBus are worlds apart.

Why PCI? There were three reasons behind Apple’s decision to adopt the PCI standard. First, speed: A PCI card today runs at 33 MHz (compare with NuBus: 10 MHz) and can transfer data to your Power Mac at roughly 20 to 40 megabytes per second — about twice as fast as a NuBus card (10 to 16 megs per second). When System 8 (Copland) finally arrives, you’ll get even better data through- put. All of this speed is extremely valuable to people who depend on net- works, work with digital audio, or make digital movies. 1006 Part IV: Attachments

ANSWER MAN But if speed were the only issue, Apple could have Using a PC PCI in a Mac done better, adopting one of many slot designs floating Q: Can I use PCI cards sold for PC around in today’s technology circles — things called (non-Mac) computers in my Power , S-Bus, or the VESA Local Bus, for example. A Mac? second reason, therefore, was cost. In theory, PCI cards A: In general, yes.There are will ultimately be cheaper than NuBus cards, largely conditions, however. First, the PCI because they’re so popular already in the competitive PC card must, of course, come with a clone market. (In fact, however, the manufacturers’ cost software extension — a driver — of adapting existing cards to work with the Mac may eat that tells your Mac how to up the savings in the short term.) communicate with it. The final reason for Apple’s switch to PCI is proba- Second, cards that need to load at bly the most important: Apple needed to reach a com- startup — like video cards and hard promise with IBM in the design of the new hybrid drive controller cards — must be “PowerPC Platform” Mac/IBM computers (see the end “Open Firmware”-compliant. (Open of Chapter 13). To create such machines, Apple and IBM Firmware-compatible cards automatically work in any Open- had to choose components that would work with any Firmware-compatible computer, operating system — and NuBus wasn’t among them. such as the Mac.) If the card doesn’t need to be loaded PCI futures when the Mac turns on — such as network cards — they don’t have to The current PCI Local Bus can transfer data 32 bits at a be Open-Firmware compliant. time. But 64-bit data “pipes,” as well as doubled 66 MHz running speeds, are in the plans for new PCI slots and cards, scheduled for debut in 1997 or 1998 Macs. Despite the PCI technology’s promise, don’t expect NuBus boards to dis- appear overnight. NuBus boards will still be manufactured for several years to satisfy the needs of millions of Mac users who have no intention of migrat- ing to PCI-equipped Macs. At this writing, you can buy Mac clones (from Power Computing) that contain both PCI and NuBus slots. Furthermore, even with a PCI-only Macintosh, your previous investment in NuBus cards isn’t worthless; for $600 or less, Second Wave (512/329-9283) will sell you an Xpanse PN, a PCI card with a 30-inch cable to an external box that holds two NuBus cards. (They also sell four- or even eight-NuBus-card models, all con- nected to a single PCI slot.)

HOW TO INSTALL A CARD If you follow instructions, you don’t endanger your warranty by installing a card yourself. Although directions may differ from model to model, here are the basics: Chapter 31: NuBus, PCI, and Other Slots 1007

First, turn off the Mac and all connected equipment. Leave the power cord plugged in, however, to act as a ground. You’re usually told to let the Mac sit for a few minutes, to give the storage capacitors in the power supply a chance to drain current. That’s just to prevent you or the card from getting “zapped” with some stray electrons. (We’ve never known any Mac or owner to be zapped from not having waited long enough after shutting down the machine, however.) Then open your Mac. Depending on which model you have, you may need a screwdriver to remove one or more screws to get the Mac’s case off. Place them in a safe place (such as an ashtray) so that you can find them later. Truth be told, we know plenty of people with desktop-style machines who change their expansion board lineup so often they never bother to reinstall the screws.

Losing charge Before you touch anything inside your Mac, touch the power supply case (the large metal silver cube inside the Mac where the power cord attaches from the outside) to discharge static electricity from your body. If your work area has a carpeted floor, or you’re living in a dry climate, you might get a tiny, harmless shock. Your hair won’t stand on end (if you still have hair and it’s not already standing up). Some manufacturers include, in the NuBus card’s box, a wrist strap to drain current. You wrap one end around your wrist and attach the other end to the power supply. You may feel like a mad scientist wearing one of these things, but we wish more hardware manufacturers offered them with their multithousand-dollar boards. If your expansion board has an external connector (such as a video display adapter or, if it’s a QuickTime movie board, a jack for a video cable), you have to remove the plastic or metal cover plate at the rear of your Mac. It pushes out from inside. We recommend that you pop it out with the end of a pencil, however, having had our knuckles ripped too many times by those sharp little prongs. You should probably save the plate after it’s out, in case you intend to remove the board later on. (We learned this lesson the hard way, when the day came when we wanted to sell a Quadra 800, and we couldn’t find the missing back-panel slot plate. The buyer put up a fuss.)

The board meeting Remove the card from its antistatic bag carefully, holding the board by its edges or by the metal faceplate, if it has one, at one end of the card. Take the 1008 Part IV: Attachments

MACINTOSH SECRET card to your open computer. Look at the bottom of HORIZONTAL SLOTS the Mac to spot the actual thin rectangular slot con- nector. Then align the card so that the matching con- In “tower”or “minitower”— nector on one long edge of it mates with the slot on design Macs,such as the Power Mac 8500,the slots aren’t on the the Mac floor. The components on the board (all the floor of the Mac; they’re on the little transistors and things sticking out of one side of sides,so the card sits the board) usually face the power supply. horizontally instead of vertically. Gently press the card until it’s seated on its connec- To keep everything securely in tor. Wiggle it back and forth slightly, to see that it’s place,Apple provides a plastic connected firmly. If you can’t get the board to fit expansion-card clip.You have to inside the connector slot, first check whether you’re remove this clip before dealing with a NuBus, PCI, or PDS board (the con- connecting your new board and reinstall it after the board is nectors are all slightly different). Don’t force it; you plugged in. don’t want a big repair bill if you bend or break the With such a tower-design Mac,it connector. If you can’t seat the board in its place, call also helps to turn your computer the manufacturer or dealer or your favorite Mac guru on its side before installing an for assistance. expansion board; installing a After the board is installed, close the Mac’s cover. card side-saddle can be Before replacing and tightening the screws, hook up awkward. your accessories and start up the Mac, just to be sure And speaking of awkward:The everything is working. (It’s perfectly okay to start up Quadra 800 is a rare Mac.It has your Mac without its cover on.) both kinds of slots,NuBus and PDS.But they’re positioned so that you can fill one slot or the other,but not both.When NUBUS AND PCI SECRETS there’s a PDS card installed,it blocks the NuBus slot. Removing the card Removing a card works almost exactly like installing ANSWER MAN one:You open the Mac’s cover, wait a few moments (if What’s a DAV slot? you believe in that),and touch the power supply. Q: Yeah—what’s a DAV slot? My Then you grasp the card at two points: The metal 8500 has one. clip at the rear of the Mac and the other bare corner of A: DAV stands for Digital Audio the card.(If it’s not a card designed to protrude out the Video.This slot can accommodate a back of the Mac, there may not be a metal clip. Grab video-compression card, although that back upper corner instead.) Tug upward, using we don’t know of anyone making the metal clip as your main handle. We usually find it such cards for this slot yet. easier to pull a card out diagonally, with the back end (with the clip) coming up first. Chapter 31: NuBus, PCI, and Other Slots 1009

How long can a NuBus card be? The original MIT NuBus standard specified that NuBus boards should be between 11 and 14 inches long. But Apple made a few changes to better suit its designs and declared that NuBus cards for Macs could be between 4 and 13 inches long. Imagine the consternation of NuBus board manufacturers, then, when the Centris 610 was introduced.Its new case design (later used in the 6100,and so on) placed a new limit on the length of NuBus cards that sent manufacturers Strange scrambling back to the drawing boards: Seven inches. Nowadays, you have to But True specify your Mac model before ordering a card so you can be sure it will fit!

Surviving the Duo Dock NuBus The desktop housing for a PowerBook Duo, the Duo Dock, can accommodate two NuBus cards. Installing or removing a card from a Dock, however, is nowhere near as easy as it is on a traditional desktop Mac. We only have one Secret to share here:Don’t install a NuBus card into a Duo Dock when you’re on a deadline. Allot an hour if it’s the first time you’ve attempted the process.You wind up taking the Dock almost completely apart, with the manual on your lap and perspiration on your brow.