On June 29, 1993, IBM released the first energy star computer, the IBM PS/2 E. The “E” stood for energy. But while it was undeniably more efficient than other desktop PCs, arguably it was a PS/2 in name only. To make the PS/2 E more efficient, IBM used a mashup of technology, including but not limited to borrowing technology from its Thinkpad laptops. To celebrate its green nature, IBM adorned it with a big green stripe across the front. Yes, the stripe was green, not the traditional IBM blue.
IBM’s green machine
Coming off a disastrous 1992, IBM came into 1993 needing to do something innovative and different. The PS/2 E was part of that initiative.
The PS/2 E lived up to its name, sipping no more than 24 watts of power. The low power consumption also meant it was quiet because it didn’t need a fan at all. It was small, too, one square foot in size and 2.75 inches tall. That’s 305mm x 305mm x 70mm for the rest of the world that uses metric. Today, small PCs that consume minimal power are relatively common, but in 1993 when full-size AT desktops were still common, the svelte PS/2 E was revolutionary.
But even though it looked like the future and was designed to not waste power and therefore preserve the future, it had trouble running the 32-bit operating systems of the future. The PS/2 E was fine for running Windows 3.1 and basic productivity apps. It wasn’t ideal for IBM’s OS/2 and would struggle with Microsoft’s Windows NT, which was also announced the same week. IBM shipped it with either DOS 5.02 and Windows 3.1 or OS/2 2.1, depending on the model number.
It looked great on an executive’s desk, especially when the executive wanted to look futuristic and forward-thinking. But someone who used a PC heavily probably needed something else.
IBM called it the model 9533 and sold it as the Model 33, 35, or Model 40 depending on its configuration. But everyone called it the PS/2 E.
What was inside the IBM PS/2 E
The IBM PS/2 E cut some corners to get its power consumption down below 23 watts. It used the ISA bus, unusual for a PS/2. No Microchannel here. That meant its XGA-2 video was on the slow 8 MHz ISA bus. It also lacked level 2 cache, so performance lagged many other 486-class machines. And it used IBM’s unusual 486SLC2 processor. This was a 386SX/486SX mashup that IBM came up with, putting a 486 core in 16-bit 386SX packaging, doubling the L1 cache to 16KB and using clock doubling to 50 MHz to compensate for the lack of a 32-bit memory bus. It was a 32-bit CPU internally but the 16-bit memory bus limited it to 16 MB of RAM and also meant it accessed memory at half the speed of a fully 32-bit processor.
It had a single ISA slot for expansion. IBM offered Ethernet or Token Ring network cards installed from the factory, or a 4-slot PCMCIA expansion card. The PCMCIA card was the most practical option since you could get a PCMCIA network card and still have room for three other various cards. To turn an IBM PS/2 E into a viable retro PC today using period correct-ish parts, you could equip one with PCMCIA Ethernet and sound cards. Or you could use something like a PicoMEM to emulate an NE2000 network card and Ad Lib sound. It’s not the ideal retro 486, but as a machine that blurs the line between a 386 and 486 and doesn’t take much space, it has its uses. And of course it’s historically important and, dare I say it, relatively rare.
It used a laptop-style 3.5-inch floppy drive and a 2.5-inch IDE hard drive. It had the 528-megabyte BIOS limit.
Critical reception of the IBM PS/2 E
The IBM PS/2 E received more coverage in the trade magazines than it did in mass market computer magazines. The consensus was that it was innovative, but came with compromises.
Compute magazine featured it in the lead editorial of its January 1994 issue. Editor Clifton Karnes probably didn’t realize he was writing the machine’s requiem, because IBM discontinued the PS/2 E in December 1993. Due to the lead times necessary when publishing monthly, Karnes may have written his editorial sometime in August or September.
He praised the small form factor and its quiet and energy saving operation. He was less excited about the small 123-megabyte hard drive and the price. He noted that it cost about $5330 with the flat panel LCD but also said money wasn’t really the object here, it was saving energy and reducing EMF radiation.
Indeed, the PS/2 E with the IBM 9507 LCD together consumed less than 60 watts. When idle, they consumed less than 33 watts. At the time, IBM estimated it used 1/4 the power of a conventional PC.
In the end, IBM sold around 25,000 PS/2 Es. Since most of them went to corporations, the majority were likely recycled when they reached the end of their useful life. Today, a PS/2 E is an interesting curiosity, a relic of a bygone era in more ways than one.
Why IBM discontinued the PS/2 E so quickly
The January 31, 1994 issue of Infoworld gives a clue why the PS/2 E only lasted about six months on the market in an article on page 64. The magazine tested 13 Energy Star-compliant PCs, noting they were “sprouting up like weeds” in their subheadline. While “IBM’s PS/2 E used the least amount of power by far in our tests,” the other 12 machines were more conventional 486DX2-based PCs, most of them running at 66 MHz. The other PCs cost up to $500 less than a PS/2 E in its least expensive configuration while running nearly 50 percent faster. If energy efficiency was your primary concern, the PS/2 E made sense. But the overall user experience was better with a more conventional Energy Star-compliant PC, including IBM’s own PS/Valuepoint.
David Farquhar is a computer security professional, entrepreneur, and author. He has written professionally about computers since 1991, so he was writing about retro computers when they were still new. He has been working in IT professionally since 1994 and has specialized in vulnerability management since 2013. He holds Security+ and CISSP certifications. Today he blogs five times a week, mostly about retro computers and retro gaming covering the time period from 1975 to 2000.
Today, small PCs that consume minimal power are relatively common, but in 1993 when full-size AT desktops were still common, the svelte PS/2 E was revolutionary.
what about Tandy 1000 RSX?
i sold my Tandy 1000 in the 90s but if I kept it I would like a 486SLC2 processor.