Looking back at the IBM PS/2

If there was ever an Edsel of the PC industry, it was the IBM PS/2 line. Originally designed to destroy the clone business, the PS/2 wound up derailing IBM instead. Here's a look back.

If there was ever an Edsel of the PC industry, it was the IBM PS/2 line. Originally designed to destroy the clone business, the PS/2 wound up derailing IBM instead.  Here's a look back.


A little over 50 years ago, Ford launched a much-hyped new car line called the Edsel, which was supposed to revolutionize the auto industry. It turned out to be a disaster. Much the same way, a little over 20 years ago, IBM introduced a much-hyped upgrade to the PC AT line, the PS/2 line, which was supposed to revolutionize personal computers.

It didn't quite work out like IBM had planned.

Attack of the clones

When IBM decided to enter the "microcomputer" market in 1981, it did so as sort of a skunk-works project. The original IBM PC was developed mostly with off-the-shelf parts with the only really proprietary part being the on-board BIOS and BASIC. As such, when the IBM PC became a smashing success that even IBM didn't anticipate, it was a ripe target for cloning.

When Phoenix Technologies successfully reverse-engineered the PC BIOS in such a way as to bypass copyright problems, the only barrier to entry by clone companies disappeared. Companies such as Compaq appeared overnight, rushed into the marketplace, and slowly began chipping away at IBM's market share.

Making a record $111 million in its first year of business in 1983, Compaq made $1 billion by 1987. IBM still was the market leader, but it didn't like the fact that Compaq and others were taking so much business. At the same time, Compaq and others began innovating ahead of IBM, such as shipping computers based on the new 32-bit Intel 80386 CPU.

IBM decided that something needed to be done with these upstarts. It decided the thing to do was reintroduce the PC in a manner that it could control the old-fashioned way -- through patent protection.

The empire strikes back

By creating a new line of PCs with technologies developed and owned by IBM itself, IBM thought that it could control the PC clone market. It could charge high enough license fees to drive marginal vendors out of business and extract a steady income from those that survived. If IBM couldn't make money off of the systems itself, it could at least have the license fees.

To this end in 1987, IBM introduced the PS/2 line. Rather than being simple PCs, the PS/2 was a "personal system." The idea behind the branding was to give the impression that IBM-branded computers were designed the same way as mini and mainframe computers -- complete systems ready for business use.

There were originally five different PS/2 models:

  • Model 25: An 8086-based machine that resembled a cubist-styled Macintosh with an integrated monitor.
  • Model 30: Also an 8086-based machine with a larger form factor and a traditional separate monitor.
  • Model 50: An 80286-based desktop machine that was physically larger than the Model 30 and much faster.
  • Model 60: An 80286-based tower
  • Model 80: IBM's first 80386-based computer, also in a tower case.

The Models 25 and 30 were vastly underpowered, even by 1987 standards. The 286 had been standard equipment for over a year, and the 386 had just been introduced, so the 8086 CPU on these new units were already obsolete. Beyond that, these machines were limited to a 720Kb low-density floppy drive where other models had a 1.44 Mb high-density drive. Finally, the graphics on these machines were hobbled to a standard called MCGA rather than standard VGA.

MCGA graphics were limited to 640x480 monochrome and 320x200 with 256 colors. It wasn't backward compatible with the then-popular EGA graphic standard either, further limiting it to games that were specifically designed for it. MCGA never gained adoption beyond the PS/2 Model 25 and Model 30.

The true innovations that IBM laid claim to in the PS/2 line include:

  • VGA graphics
  • 3.5" floppy drives
  • PS/2 keyboard and mouse ports
  • MicroChannel Architecture bus

Of the technologies listed, the first three survived well into the twenty-first century. Naturally, some of them, such as VGA, advanced over time to the standards that we have today, but they all got their start with the PS/2.

The Mac introduced the 3.5" drive, but the PS/2 made it a standard. The floppy drive maintained its same form for almost 20 years. Manufacturers tried to upgrade the standard several times, but they always fell back to the old 1.44Mb format. It was only in the past two years that 1.44Mb floppy drives didn't come as standard equipment on PCs.

Likewise, it was only recently that the PS/2 mouse and keyboard port fell off the radar as standard equipment. The USB port has mostly bypassed this standard, but you can still find it on some machines.

The only major thing introduced in the PS/2 that you don't see today is the MicroChannel bus. This is also the thing that probably doomed the line.

The magic bus

MicroChannel was a wholly owned IBM innovation. It was designed to overcome the problems with the standard ISA bus of the day. The ISA bus was 8- and 16-bit standard for expansion cards for a system. It was a shared bus where each card in the system shared bandwidth and CPU access.

Another limitation to the ISA standard was configuration. If you remember back to those days, expansion cards came with DIP switches and jumpers that needed to be manually set on the card before you installed them in the system. You had to know and keep track of all the settings so they didn't conflict with existing cards.

Although Plug-N-Play with PCI ultimately solved this problem, the PCI standard wouldn't appear on the scene for another five years after IBM introduced MicroChannel. MicroChannel's solution was to use a configuration disk. When you installed a new device, you also had to insert a "reference disk" that would examine the system and configure the card appropriately. Naturally the drawback to this meant that you had to keep track of and rely on configuration disks that could go bad.

MicroChannel's major drawback was the fact that IBM charged licensing fees for it rather than making it an open standard. This caused almost all computer manufacturers of the day to completely bypass it. Of the major computer makers of the time, only Radio Shack supported the MicroChannel bus in its Tandy 5000MC.

As noted in the link, a 23-year old Michael Dell announced a pair of MicroChannel Dell PCs, but I couldn't find any reference to Dell actually shipping the units. We had some 5000MCs at the Radio Shack Computer Store I worked at once, but I don't remember actually selling any of them.

Rather than pay tribute to IBM, the very OEMs that IBM tried to fleece with the MicroChannel bus turned against it and created their own standard called EISA. This was a self-configuring 32-bit extension of the ISA bus. It didn't gain much traction outside of the high-end and server market and wound up being supplanted by PCI.

An unhappy ending

In the end, IBM lost even more market share after the introduction of the PS/2. Part of the problem was the relative high cost of the PS/2 over clone makers, but a lot of the problem came from the lack of adoption of the MicroChannel bus.

Like Ford, which stuck by the Edsel for a few years, IBM continued to market and upgrade the PS/2 line for several years. It tossed out the low-end Model 25 and 30 and replaced it with 286- and 386sx-based units, such as the Model 30-286 and Model 55sx. PS/2s running Intel's 80486 were introduced over time as well.

Eventually, however, IBM abandoned the PS/2 line. It survived until IBM relaunched the PC brand in an attempt to reboot its image in the marketplace. The MicroChannel bus lived on a few years in server machines, but eventually PCI completely took over.

Take a look inside

We recently got a hold of a later model IBM PS/2 Model 55sx. This is a 16Mhz 386sx-based machine that came with 4MB of RAM and a 40MB hard drive. The original price of a 30MB Model 55sx was $3,895 as you can see from a New York Times article in 1989. Adjusted for inflation, that's over $6,400 in 2007 dollars.

Check out some of the innovations inside the PS/2 by browsing the IBM PS/2 Model 55sx Cracking Open Photo Gallery.