Background & history

The IBM P75 was the most powerful portable computer released in 1990 as it was the first mobile computer to sport the then cutting-edge, Intel 486 CPU. It was also perhaps the most expensive personal computer that you could commercially buy – depending on configuration, the P75 could be priced north of $18,500 or about $37,500 in 2020 dollars!

Here is the price sticker on a P75 – $18,890 in 1990, which translates to $37,565 in 2020, Enough for a new Tesla Model 3!

This computer was not something that you could pick up at the local computer store – the IBM P75 was a Ferrari (or literally a modern Tesla’s worth) of mobile computing and were to be ordered direct from IBM or an authorized dealer. But this begs the question: why did a computer the size of a briefcase cost as much as a luxury car in 1990?

A complete desktop on the go – this was cutting edge tech 30 years ago!

The Landscape

Let me remind you of the year – it’s 1990. We saw the start of the Gulf War with Iraq invading Kuwait – we also witnessed the launch of the Hubble Telescope and the airing of the first Simpsons episode. The dawn of a new decade was upon us, with pop culture and technological innovation shifted into overdrive.

The Hubble Space Telescope, launched in 1990 – interestingly, it was upgraded to a 386 based CPU in 1993, then was only upgraded in a service mission to a 486 in 1999.

Intel had just unleashed the next generation i486 CPU, setting the stage for more sophisticated software (most importantly games) and GUI-based multitasking to come. The new 486 CPUs were pricey, however, and only those needing computing horsepower for AutoCAD and the like bought them at first. Other than CPU innovations, color displays had also just hit the market, with the release of the NEC Prospeed CSX – a $9,000+ A/C powered portable, with EGA resolution and 16 Colors. Impressive right? Oh, by the way, the screen measured a massive 8 by 5 inches, and the “laptop” weighed a knee-crushing 19 pounds. Portable computing in 1990 was really just getting on its feet.

Talk about washed out! But it’s not the magazine – look at the cup of tea and the oranges at the bottom left, then look at the smudge of a screen, all yours for US$9,000 (about US$18,000 in 2020 dollars). Long term use “questionable” indeed.

Though buying a 19-pound laptop with a palette of 16 washed-out colors may seem comical to us today, other brands had begun to find their footing (and thankfully beginning to take the weight off our shoulders). Portable computers were beginning to be measured in inches instead of feet, though most were still hefty, thick, and now only slightly back-breaking.

Dell Computer’s typical aggressive ads against Compaq from 1990 – these two models represent a typical, new upmarket laptop at the time. They were above average in terms of performance (They were 386 SX based) – but note how thick these laptops were. The Compaq SLT 386s/20 weighed 14 pounds and came with a built-in carrying handle.

That is not to say all laptops in 1990 were overweight – some especially light models had already entered the exclusive “5-pound-or-lighter club”. Though some very early 90s laptops had shed the weight, they had also shed their performance too, with these early “notebook-type” laptops being vastly underpowered. This deliberate reduction of performance was a necessary compromise as high-performance components weighed more and demanded more power. Don’t forget, battery technology at the time was primitive – an average 286 based laptop could barely stay powered for a couple of hours and were not able to sufficiently power a 486-based portable machine in 1990.

The NEC Ultralite, released in 1988, was the thinnest laptop made at the time, weighing in at 4.4 lbs. The downside? No hard disk (early SSD type disks were used, with 2MB capacity), no floppy disk (data transfer by serial cable), and 640K of RAM and an 8088 compatible CPU. Definitely does not run DOOM.

Another reason why lighter laptops lacked performance was that miniaturized high-performance components simply did not exist; the miniaturization of high-performance components (like large capacity hard drives, or a low-power-consumption version of the 486 CPU) for use in laptops were on the horizon, but would only become available in 1992.

The original “desktop” version of the Intel i486 DX-25 CPU from 1989 (background) with miniaturised i486 SL-25 superimposed (foreground) shown roughly to scale. When the 486 SL was released in 1992, the desktop i486 had already been made obsolete by the new DX2-66 (66Mhz), which was the same size but performed twice as quickly, but with increased power consumption.
Slimmer and more powerful laptops like the one above did not hit the market till 1991 – but even when they did, they were still using 386 CPUs (in this case a 20 Mhz 386 SX). A battery-powered laptop using miniaturised 486 chips (486 SL) wouldn’t be seen on shop shelves till the end of 1992.

The need for portable desktop-grade performance in the late ’80s and early ’90s gave rise to “portables.” These were a class of mobile computer that did away with batteries, and instead, crammed as much power-hungry, high-performance components as could be put in a relatively “transportable” package. If you haven’t noticed, we love portables here on Retropaq! (Check out Compaq’s last portable computer, the Compaq Portable 486 from 1992, and the funky lunchbox shaped Compaq Portable 386 from 1987) These portable computers were not designed to be used on a plane; instead, these portable desktop-class computers were intended to be plugged into the wall when you moved from point A to point B.

These high-powered portables were sure to turn your colleagues green (or orange) with envy back in 1990 – expensive and A/C powered, but expandable and most importantly, portable and just as powerful as a desktop. Shown is a 386-based Toshiba T5200.

Although relatively heavy compared to laptops, portables were quite svelte and compact compared to the traditional 80’s luggable. Some were laptop shaped (though really not intended for use on your lap, due to their weight), and others were briefcase shaped. These computers had reduced portability but vastly outperformed battery-powered laptops. Portables were really in a class of their own, with most of the high-end portable pedigree being deployed in exotic applications such as portable file servers, building-worksite AutoCad stations, or even as the personal computers of high-level, high-upper-back-strength executives, who needed power and performance at any cost.

He’s certainly happy to be going to his next meeting! This important looking fellow here is shown with the 386-based IBM P70, the P75’s younger brother from 1989. If you swung a P75 like that, you would definitely take someone’s knee out!

Enter: The IBM P75

The IBM P75 was the most powerful portable computer that money could buy in 1990 by a huge margin. Being the first mobile computer to use the Intel 486 CPU really set the IBM P75 apart. Other high-end portables were running 386 DX’s, which were fast – but the 486 was on a whole other level. People didn’t even quite know what to use a 486 for in 1990, aside from greatly speeding up AutoCAD and acting as portable servers. But, let’s put it this way – a 386 would comfortably run Windows 3.1 with excel and word processing, but a 486 could handle running Windows 95 – where you could surf the net with Netscape Navigator and run SimCity 2000 (albeit in a world of orange) in a separate window with no problem.

In fact, the P75 was described as a portable “server” due to its then-immense computing power. It came with a VGA amber/orange gas-plasma display, capable of simulating 16 shades of grey (more like 16 shades of orange), a full travel IBM keyboard (quite clicky), a large SCSI hard disk, and a floppy drive making it a truly portable desktop-class computer.

Here are the detailed specifications of the IBM P75:

Brand, Model Name & NumberIBM PS/2 Model P75 486 – Model 8573-161 (160 MB Hard Disk Drive) – Model 8573-401 (400 MB Hard Disk Drive)
CPU486 DX-33 with 66.666 Oscillator, CPU and Oscillator can be modified to be socketed.
RAM16 MB – 4X 4MB 72 Pin Simms 70 NS Parity
Expansion4 MCA Slots – 32-bit AVE, 32Bit MME, 2x 16 Bit Short
Hard DriveOriginally 160 MB or 400 MB SCSI 1 – 1 GB Max Capacity, can use SCSI2SD
Floppy Drive1.44 MB IBM standard proprietary drive
Internal VideoOnboard XGA-1, Gas Plasma, 640×480, 16 Greyscale, 10 inches.
External VideoOnbaord XGA-1, 256 color (can be upgraded to High-Color on Win 95 with 3rd party drivers) at 800×600
PortsParallel Port, Serial Port, VGA port, PS/2 Mouse Port, External Floppy Drive Port, SCSI-1 Port (C-60)
Information as presented in PC Magazine Vol 10. #5, March 12, 1991

As you can see – its specs are pretty impressive and more fitting of an average desktop computer from, say 1993, which is why the P75 cost as much as a luxury car at the time.

Needless to say, not too many of these IBM P75’s were made – concrete production or sales numbers from IBM are hard to find. However, it’s safe to say whilst there were niche applications for the IBM P75, it wasn’t something your average Joe would be buying. If you had one of these in 1990 – please, please leave a comment and tell us what it was like to use this screamer-rocket of a computer back in the day!

Take a Closer Look at the IBM P75:

The Most Powerful Portable – IBM P75

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5 thoughts on “The Most Powerful Portable – IBM P75

  1. I used one of these when I was a kid. I used to play Indianapolis 500 on it. It was the mid-90’s and my dad got one of these machines from his workplace for some time. I remember the machine being super heavy (I was ~10 years old) and the screen was quite bad especially when it was sunny outside.
    I had no idea these machines were so expensive. My dad never used it for work. It was basically a toy for me during the summer. I remember we had the machine at our cottage, where I set it up on the floor of the kids’ room and messed around with it and played that Indy500 game.
    I suppose that by around 1994-1995 lighter and faster portable computers were available and these beasts had become obsolete, and that’s why my dad was given one just for fun. Now I’m left wondering if the machine still exists in some dusty storage room at my dad’s workplace. It would be fun to use it now that I actually understand something about computers.

    1. Sorry I missed your comment! You were a very lucky kid! The only hand me downs I got from my dad were much older computers. The IBM P75 is amazing – the first portable 486 computer and pretty capable, though you are right by 1995 laptops had pretty much kicked it’s butt. I still use mine though as my main 486 computer for retro gaming hooked up to an external CRT 🙂

  2. Fantastic! Wish I could use one of the 640×480 plasma displays for my office work… is that even possible with HDMI to VGA to 14-pin adapter? No one knows…

    1. Yeah it’s also my dream to hook up the monitor to a modern output, but I’m not skilled enough in the electronics department to make a VGA input to the screen. One day…

  3. I have two of these that I bought off Ebay 20 or so years ago, but both arrived with cracked screens. I kept them, but would now love to get them working. Does anyone know if the plasma screen is available anywhere for purchase?

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