Power for the Rest of Us art

 

 

Power For the Rest

of Us

 

Power Macintosh offers lightning speed and a host of questions.

In 1984, the Macintosh 128K burst onto the computing scene. Well, okay, it crept onto the scene. The "computer for the rest of us" was a risky venture that could easily have fizzled. The world was ready for the Mac's graphical user interface; Apple just needed to explain that fact to the planet's unsuspecting inhabitants in an evangelical PR campaign. In the decade that followed, all Macs that ever lived were built around a single family of microprocessors, the Motorola 68000 and its descendants.

But no more; the PowerPC chip has been born, and the 680x0 clan appears headed for the spare-parts bin. The product of a once-unthinkable alliance between Motorola, Apple, and IBM, the PowerPC family of high-speed microprocessor chips will be the brain of most Apple and IBM personal computers in the future.

Apple, for one, is putting all its high-tech eggs in the PowerPC basket. In the midst of another evangelical PR campaign, the company is moving quickly to phase out most of its high- and mid-level 680x0-based Macs and almost certainly will phase out the rest of them in the next year or two. The Quadra AVs, 610, 650, and 800, will almost certainly be history in the near future.

Of particular interest to musicians, the blazing speed of the PowerPC makes the new computers capable of recording and playing 16-bit digital audio without using a DSP coprocessor. As we'll see later, however, there appear to be several "ifs" and "buts" to this capability.

Taking RISCs
The PowerPC chip is not simply a faster conventional microprocessor; it has a completely different architecture than the chips used in previous desktop computers. The Intel 80x86 and Motorola 680x0 chips that provide the brain power for Ataris, Amigas, PC-compatibles, and pre-PowerPC Macintoshes are Complex Instruction Set Computing (CISC) chips. These chips contain a wide variety of instructions that enable the computer to carry out its functions. The much-ballyhooed Intel Pentium is a very fast, highly integrated CISC chip. In that sense, it is a further development of current desktop-computing technology.

Motorola, Apple, and IBM believe that CISC technology has almost reached its performance peak. (Motorola is working on a 68060, however, and DayStar Digital will offer current Mac users a series of accelerators based on it.) Apple sources state that further integration of CISC chips will increase the size and heat output of the chip but provide only a minimal gain in speed. Instead of continuing down the CISC path, the partners decided to tap the power of an alternative chip architecture, Reduced Instruction Set Computing (RISC).

The main difference between CISC and RISC is that instead of the wide variety of instructions contained in a CISC chip, a RISC: chip only contains the instructions used most often. However, it can execute these basic instructions extremely quickly. When complex instructions are required, the RISC chip builds them by combining sets of basic instructions. This means that most operations are handled far more rapidly in RISC than in CISC. (The hardware details of Power PC RISC chips were discussed in the March 1994 "Tech Page.")


RISC chips of various types have been around a long time, powering various primarily UNIX-based, systems such as engineering workstations, high-end graphics machines, and large, commercial database servers. However, this constitutes a relatively small volume of expensive chips. Until the development of PowerPC, nobody marketed an affordable RISC chip that could run familiar operating systems such as Microsoft DOS and Windows and Apple System 7. In contrast, Motorola, Apple, and IBM are developing a full line of PowerPC chips and products for desktop computers, network servers, portables, workstations, and even consumer electronics.

Welcome To Power Mac
Apples line of PowerPC machines are the first to reach the market. Dubbed Power Macintosh, Apple's new machines began shipping in quantity on March 14 of this year. These computers are still Macintoshes: they run System 7 (v.7.1.2), work with Mac peripherals, and are expected to run the overwhelming majority of 68040-compatible and System 7-compatible applications. (For details on the first three Power Macintosh models, see sidebar "The Power Macs That Be.")


Apples Power Macintosh 8100/80 is by far the fastest Mac yet. It comes with all the trimmings, including two independent monitor outputs, a 14-inch Macintosh Color Display, three full-size NuBus slots, 8 MB of RAM, and eight additional SIMM slots.

In addition, UNIX fans should be able to run Power Open, a replacement for A/UX, sometime later this year. A Power Mac version of the Taligent operating system is also in the works. To top it off, Insignia Solutions is offering Soft Windows, which lets you run DOS and Windows applications on a Power Mac (see sidebar "Power Windows"). (IBM's as-yet-unreleased PowerPC computers also are expected to run several operating systems, with the primary focus on Windows NT and OS/2.)

The first three Power Macintoshes off the line use the first-generation, 32-bit PowerPC 601 chip and replace the mid- to high-end Quadras. Early next year, the 601 chip will be joined by the low-power, low-heat PowerPC 603. The 32-bit 603, which is already in production, is a tad slower than the 601, so it probably won't obsolete the current crop of 601-based machines. Unlike the older chip, however, the 603 offers four software-controllable power-saving modes, including a dynamic mode that automatically puts inactive areas of the microprocessor in a low-power state. This makes it Apple's choice for portables, as well as LCs and Performas.

Despite his title, Senior Editor Steve O is not an Ancient, nor does he only edit articles written by septuagenarians. He has, however, worked in EM's editorial department longer than any of these young whippersnappers.

This article is reprinted from the May 1994 issue of Electronic Musician magazine with the permission of its publisher, Penton Media. For more from EM, please visit www.emusician.com.