From 128K to Quadra: Model by Model
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Chapter 12 From 128K to Quadra: Model by Model IN THIS CHAPTER: I What the specs mean I The specs for every Mac model ever made I Secrets of the pre-PowerPC Mac models I Just how much your Mac has devalued Yes, we’ve already been told that we’re nuts to attempt the next two chapters of this book. Since 1984, Apple has created more than 140 different Mac models — including 35 different PowerBooks and 53 different Performas! Each year, Apple piles on another dozen or so new models. By the time you finish reading this page, another Performa model probably will have been born. So, writing a couple of chapters that are supposed to describe every model is an exercise in futility. But we’re going to attempt it anyway, taking the models one by one and tracking their speeds, specs, and life cycles. This chapter will cover all the Apple Macs — both desktop and portable models — from the birth of the original Macintosh 128K to the release of the PowerBook 190, the last Mac ever made that was based on Motorola’s 68000-series processor chip. When you’re finished reading this chapter, you will be one of the few people on Earth who actually knows the difference between a Performa 550, 560, 575, 577, 578, 580, and 588. 375 376 Part II: Secrets of the Machine Chapter 13 will cover every Power Mac — or, more accurately, every PowerPC-based machine (those with four-digit model numbers) — from the first ones released in 1994 to the models released just minutes before this book was printed. Of course, what separates the models in this chapter from those in the next is the microchip: At the heart of every Power Mac is the PowerPC chip, a faster, cheaper, and more energy-efficient microchip. (For details, see Chapter 13. And for news on models released after you bought this book, check the Secrets Web page at http://www.idgbooks.com/ idgbooksonline/macsecrets.) Despite the seemingly pointless array of nearly identical models, Apple’s lineup actually has some logic: There are exactly four classes of Macs. For the portable person, there are PowerBooks. Educational customers alone are now offered the LC series. For the home market, there are Performas. And for business use, there were the Quadras and now their potent replacements, the Power Macs. Of course, Apple is never completely consistent in its marketing distinctions; the first LCs, for example, were not restricted to educational buyers — but across the model lines, there’s considerable duplication. At any rate, keep the laptop/education/home/business distinction in mind as you read. (All photos are courtesy of Apple Computer, Inc.) COMING TO TERMS We really don’t like using technical terms — we cringe every time we find ourselves saying things like,“That microchip lacks a PMMU.”But when com- paring various Mac models, you must understand what some of the technical specifications really mean. Here’s a guide to the terms we’ll be using. Processor chip: Sometimes called the CPU, this chip is the absolute guts of the computer, a collection of microscopic transistors etched in a single square silicon chip. This microchip does the actual data processing. Until the Power Macintosh, all Macs were built around one of four microprocessor chips manufactured by Motorola: the 68000, 68020, 68030, and 68040. The higher the number, the more powerful the processor. (The Power Macintosh uses a PowerPC chip — the 601, 603, or 604, for example — as you’ll find out in the next chapter.) Clock speed: This number is the other important speed statistic for a Mac. It refers to the speed at which data moves through the Mac’s circuits, as mea- sured in megahertz, or millions of cycles per second. The earliest Macs ran at 8 MHz; the newest Power Mac models run at speeds of up to 225 MHz. (The Chapter 12: From 128K to Quadra: Model by Model 377 Power Macs’ names actually hint at their speeds; the ANSWER MAN 7200/75 model, for example, runs at 75 MHz.) Two Mac Apple’s “clock-doubled”marketing models may use the same microprocessor yet run at dif- Q: The specs for a Quadra I just ferent speeds — because one has a lower clock speed. bought say it has a “66/33 MHz” Note well, however: A faster clock speed doesn’t neces- processor.Which is it — 33 or 66? sarily mean a faster Mac. The computer’s processing A: In 1994, Apple started this new speed is determined by the particular processor chip and twist in advertising the Macs based the speed at which it is set to run. For example, a Quadra on the 68040 processor chip 630 running at 33 MHz is faster than a IIfx running at 40 (Quadra models, for example). (IBM- MHz — because the Quadra’s 68040 chip is inherently clone manufacturers had been faster than the IIfx’s 68030 chip. As a rule, you can’t com- listing speeds this way for years.) The higher number refers to the pare MHz across processor chips. (Keep that startling fact data speed inside the processor; the in mind the next time somebody brags about the speeds lower number is how fast data in the PC world. “My Pentium runs at 110 MHz for the moves through the computer itself. price of a 75 MHz Mac,”you’ll be misleadingly told.) For the sake of comparison with Data path: The wider the data path, the larger the other Macs, the lower number is chunk of data that a microprocessor can push through what counts. the Mac’s circuits at one time. (Most manuals and articles prompt you, at this point, to imagine lanes on a high- way.) The wider the data path, the faster the Mac. Macs with a 16-bit data path are notably slower than those with a 32-bit data path. The PowerPC chip uses a 64-bit data path, which is one clue to its speed. Processor-Direct Slot (PDS): This connector inside some Macs lets you plug an expansion card (such as an accelerator, digitizer, or video card) directly into the computer’s main processor. Each Mac can have only one PDS — and, alas, cards for one Mac model’s PDS might not fit a later model’s. NuBus slot: Like a PDS, this is a thin rectangular connector into which expansion cards can be plugged. A Mac can control several NuBus cards simultaneously. A IIvx, for example, has three NuBus slots; the II, IIx, and IIfx had six (the most ever). For eight years, most desktop Macs included this kind of slot. (See Chapter 31 for more on NuBus and PDS.) PCI: You’ll see this term mostly in the next chapter, which covers Power Macs. PCI stands for Peripheral Component Interconnect, and it’s Apple’s new design for expansion slots, replacing the NuBus slot. PCI cards are supposed to mean lower prices and faster speeds than NuBus cards. (Again, see Chapter 31 for more.) 378 Part II: Secrets of the Machine PMMU: This acronym stands for Paged Memory Management Unit. It’s a coprocessor (a second “brain” designed to take some of the load off the main one) specifically designed to handle memory-related tasks. PMMUs are sig- nificant for only one reason: They allow a Mac to use virtual memory (see Chapter 9). In the following discussions, we won’t specifically identify models with PMMUs; but any Mac based on a 68030, 68040, or PowerPC processor has the PMMU (and virtual memory). (A PMMU was optional on a few 68020-chip Macs.) FPU: This stands for floating-point unit, the math coprocessor chip included in some Macs to handle certain mathematical computations, such as trigonometric and logarithmic calculations. Read this twice: For most everyday tasks — word processing, database, or even fairly complex business spreadsheet work — an FPU makes no difference to the speed of a Mac. Only if you get into heavy-duty math applications, high-end drafting, a few Photoshop filters, or 3-D rendering does an FPU speed things. The FPUs used in Macs are Motorola 68881 or 68882 chips, or they’re built into the ‘040 processor. (The Power Macs have a powerful, redesigned FPU — so different that non-PowerPC software can’t use it.) SIMM speed, SIMM type: SIMMs (Single Inline Memory Modules) are the little circuit cards you plug into a Mac to increase the amount of RAM avail- able. (See Chapter 9 for details.) Some types of SIMMs take longer to produce a requested piece of information for delivery to the main processor. This speed is measured in nanoseconds (ns) — billionths of a second. Some Macs require faster SIMMs to take advantage of their microprocessor’s speed. Each new generation of Macs tends to require a different type of SIMM, too — chips of different sizes and numbers of pins, for example. The newest Power Macs use DIMMs (Dual Inline Memory Modules), yet another per- mutation of the memory chip. We include this information in the following discussions so you’ll know that, for example, the 20MB of extra RAM you bought for your Quadra won’t work in your new Power Macintosh. VRAM: In Mac models that include built-in video support (those that don’t require the purchase of a video card), monitor display tasks are handled by separate VRAM,or video RAM. As we discussed in Chapter 11, VRAM consists of memory chips mounted on the main logic board. Generally, you can expand your Mac’s VRAM if you want to increase the number of colors a Mac can display, or if you need more VRAM for a larger monitor.