There’s Life After IBM for Old PCs

Despite the turmoil brought on by IBM’s introduction of a more powerful family of microcomputers, some of the machines that the new IBM equipment was intended to improve upon still have a bright future.

Namely, the personal computers equipped with Intel 80286 microprocessors and modeled after IBM’s PC AT.

What ensures their future is that they are fully compatible with the older, slower PCs; they can use the same 5-inch disks upon which hundreds of millions of programs and data are stored; they can house a huge variety of expansion circuit boards to upgrade their performance, and they will be able to take full advantage of OS/2, the operating system being written for the new generation of IBM computers, which can run more than one program at a time.

In contrast, while IBM’s new generation of 80286 computers--the Personal System/2 Models 50 and 60--are decidedly faster than its PC AT, they have some shortcomings: They require 3 1/2-inch disks and are unable to use any existing expansion circuit cards.

If speed is what you’re after (and who isn’t?), you might consider one of the AT-compatible computers that run faster than the IBM AT.

We’ll take a look at three such computers this week: the AST Premium 286, which runs at 10 megahertz (10 million cycles per second) compared to the IBM AT’s 8-MHz, and Compaq’s Deskpro 286 and Portable III models, both of which operate at 12-MHz.

The Premium 286 runs at three speeds--6-, 8- or 10-MHz--to give it full compatibility with software written for the AT. It also offers an enhanced graphics adapter, or EGA, to produce higher resolution and more colorful text and graphics than the old standard IBM color graphics mode. In addition, AST’s adapter can emulate the popular high-resolution Hercules monochrome graphics mode for which much software is written.

I tested all three computers using the System Information test from the Norton Utilities software package. The test gave the Premium 286 a computing index of 11.1, compared to 7.1 for an IBM AT with an 8-MHz microprocessor. (The slower IBM PC XT has an index of 1.0 in the Norton test.) The Premium 286’s pace, which is faster than that of the Compaq machines, is achieved with a nifty internal design trick called a “zero wait state.”

Because the AST has very fast memory chips, it never has to make the microprocessor skip cycles waiting to get data from memory to process. The Compaq and most other AT-type computers have to skip a beat to wait for data.

The AST can accommodate up to 16 megabytes of RAM operating memory and has two special high-speed slots not found on a standard AT to allow it to run so fast.

The Deskpro 286 wasn’t far behind, with a Norton computing index of 10.3. To maintain compatibility with speed-sensitive programs, both Compaq models also can be run at the standard 8-MHz AT speed.

The Deskpro 286 I tested had an enhanced graphics adapter and color monitor, extra-cost options. The standard equipment is Compaq’s dual-mode adapter and monitor, which can display both high-resolution monochrome text or low- and medium-resolution graphics rendered in shades of green or amber.

Up to 2.2 megabytes of RAM operating memory can be installed on the main circuit board, and a total of 8.3M can be installed using expansion memory boards. There are eight standard AT-style expansion slots inside.

The Compaq Portable III was slightly slower than the Deskpro, clocking 9.8 on Norton’s computing index.

Those familiar with previous Compaq portable models will find this one radically different. It is much smaller, though still not a laptop or briefcase type of machine.

In place of the 9-inch monochrome video tube monitor of the earlier portables, the III sports a flat, gas plasma display that shows bright orange characters against a duller orange background. It can display monochrome text and graphics at a resolution slightly higher than that of the EGA adapter.

The Portable III comes with a 5-inch standard AT-style, 1.2-megabyte floppy disk drive and either a 20M or 40M hard disk. An internal Hayes-compatible, 1200-baud modem is an option, and 640 kilobytes of RAM operating memory is standard.

The Portable III has no expansion slots inside, but you can buy an expansion attachment, a plastic case that snaps onto the back of the computer and houses two standard AT-style expansion boards. Among the boards you can buy are Compaq’s enhanced graphics adapter, which would must be connected to an external monitor, and a memory expansion board capable of housing up to 6M of additional RAM.

At 20 pounds, it is much trimmer than the original portable and easily carried with the optional over-the-shoulder bag.

My only complaint is that you have to pry open the expansion attachment housing with a screwdriver to get inside. There’s got to be a better way.

The Compaq Deskpro 286 with 640K of RAM and a 40M hard disk has a suggested retail price of $4,999. The enhanced graphics adapter is an additional $599, and the color monitor costs $799.

The Compaq Portable III with 640K and a 40M hard disk goes for $5,799. The expansion adapter costs $199; and the internal modem is an additional $399.

The AST Premium 286 with a 40M hard disk also comes standard with one megabyte of RAM and a multimode enhanced graphics adapter for a suggested retail price of $3,495. Adding a monochrome monitor is $195, while a color EGA monitor is $695.