There is a fuzzy dividing line between personal computers and a class of computers known as workstations, and the boundary is constantly drifting upward as PCs become more powerful.
In general, though, a workstation can be defined as a single-user computer that is more powerful than the fastest PC, but not as powerful as the minicomputers used by businesses to run entire departments.
Workstations are typically used for such specialized tasks as computer-aided design and engineering, scientific modeling, financial analysis and the manipulation of complex graphics in advanced desktop publishing.
The background definition is necessary because Radius Inc. has made the line even fuzzier with a new plug-in card called the Rocket, which transforms Macintosh II computers into something very much like a high-performance workstation, for much less than workstation prices.
The $3,495 Radius Rocket co-processor board, which adds a 25-megahertz Motorola 68040 microprocessor to the Macintosh, is especially appealing for users who work with big color images or other complex graphics.
Plugging a Radius Rocket card into a Mac II, IIx or IIcx computer can create a machine that significantly outperforms Apple's top-of-the-line Mac IIfx, which uses the older Motorola 68030 chip.
The difference is that a new Mac IIfx costs at least $6,000. (Apple does not offer any computer using the more powerful 68040, although one is in the works.)
The Rocket costs $500 more than Apple's own IIfx upgrade kit, which transforms older Mac II's into IIfx's. Again, though, the IIfx upgrade is based on the three-year-old 68030 chip, while the Rocket leapfrogs anything Apple has today.
Also, the Rocket can be installed easily by the user, while the IIfx upgrade has to be performed by a technician.
The Rocket comes without memory, but the user can transfer to it any combination of memory chips used in the Mac II. (The IIfx upgrade requires special 64-pin memory chips.)
Radius asserts that the Rocket will increase the performance of a Mac II to a sustained rate of 20 million instructions a second (mips), which rivals some computer systems costing 10 times as much.
In contrast, the old Mac II on our desk here has a peak performance of about 3 mips, and the newer Mac IIfx is rated at 8 mips.
Although it sounds like a dream device for speed freaks, the Rocket may also have broad appeal for anyone who has been frustrated by the relatively pokey performance of an older Mac II.
"This is not just for traditional, high-end applications like 24-bit color and 3-D modeling," said Nick Arnett, president of Multimedia Computing Corp. of Santa Clara, Calif. "I go nuts waiting for my screen to get redrawn in my desktop publishing program."
Besides the added number-crunching power of the 68040 chip, the Rocket contains a special Quickdraw accelerator that greatly speeds the process of displaying information on the computer screen.
In a side-by-side comparison of a Mac IIfx and an older Mac II equipped with the Rocket, Radius officials showed that the Rocket system ripped through a multipage desktop publishing document before the IIfx had even finished the first page.
"We put Rockets in our Mac IIx's and they actually outperform our Sun Sparcstations," said Ed Dennis, special projects engineer for the Margent Group of Richardson, Texas, a company that specializes in sophisticated electronic publishing systems.
Dennis said that other than some "idiosyncrasies" with Microsoft Word, the Rocket appeared to be fully compatible with all existing Macintosh software.
The key, he noted, is that the Rocket supplements, rather than replaces, the processor already in the Mac. A software switch allows the user to temporarily disable the Rocket for any applications that have problems with the faster processor.
Since the Mac's original processor and memory systems remain intact, the Rocket creates the opportunity for a fancy technique called multiprocessing, where soft ware tasks are divided between two or more processors working concurrently.
For example, the Rocket might take over all mathematically intensive tasks while leaving relatively simple housekeeping chores to the original processor.
It might, say, take over the millions of calculations needed to display a full-motion color video image while the Mac's original 68030 or 68020 chip handles the soundtrack.
Dennis said that some programs, such as Versacad, a computer-aided design package, already take advantage of the Radius' special QuickCAD Graphics Engine.
Makers of printers, scanners and hard disks are also expected to tap into the Rocket's built-in processor-direct slot, which could lead to new peripherals that outperform anything on the market today.
Apple is expected to introduce its own 68040-based "tower configuration" Macintosh later this year, and some Mac users who have been frustrated by the relatively slow performance of the Mac II family will certainly wait to see what Apple offers.
Mac II owners who are impatient, and those who may not care to face the expected high price of the forthcoming 68040 Mac, may find the Rocket upgrade a very attractive alternative.
Radius, of San Jose, Calif., can be reached at (408) 434-1010.