Tuesday 21 March 2023

IBM PC/XT vs Compaq Portable (1983)

Introduced March 1983

The launch of the original IBM PC in 1981 cause a fundamental shift in the desktop computing market. Out of the apparent chaos of a myriad of (mostly) startup companies offering business computers came the biggest player in the market – IBM. The original PC wasn’t the best, most innovative or cheapest product on the market by a long shot, but IBM was a serious player that business had heard of and it was an immediate sales success.

The original IBM PC had some significant shortcomings, in particular there was no hard disk and the limited expansion slots filled up very quickly. The upgraded PC/XT added a 10MB hard drive as standard, plus three extra slots, more RAM (up to 640Kb) and ROM and it upgraded the storage of the floppy drive to a maximum of 360Kb.

It wasn’t a huge upgrade over the original, but it addressed the shortcomings of the previous model well. It was probably the computer that IBM should have launched to begin with, but at over $7500 at launch, the PC/XT was really expensive.


Uniquely for IBM, the architecture of the PC was quite easy to copy. Buying in industry-standard components such as the Intel 8088 processor and making detailed hardware specifications available made it possible for other companies to make PC clones that could be better and cheaper at the same time, and Microsoft could sell you the same operating system – MS-DOS – that the PC ran to ensure compatibility. First out of the door was the Columbia MPC 1600, but more followed.

At about the same time, another trend for “luggable” all-in-one computers was starting, with the CP/M-based Kaypro II being a popular example. Texas-based Compaq Computer Corporation combined both a PC-compatible computer in the convenient form factor of a transportable machine to create the Compaq Portable, their first product.

“Portable” was a stretch, at 13 kilograms or 28 pounds it was not an easy thing to carry. Nonetheless, it could be moved easily without unplugging a vast number of cables and components. With the keyboard clipped into place, the Compaq Portable could fit into the overhead luggage compartments on a plane, or be easily placed into the boot of a car.

Compaq improved on the PC’s architecture in their own way, broadly similar to the PC/XT. There was no hard disk as standard, but users commonly added one. The Portable was also cheaper to get started with than the PC/XT. Despite being something of a niche product, the Compaq Portable sold tens of thousands of units in its first year, and it made Compaq Computer Corporation a very successful rival to IBM in the PC market.

Compaq Portable
Compaq Portable

IBM and Compaq duked it out in the market until the mid-2000s, with IBM eventually selling off its PC business to Lenovo and Compaq merging with HP.

Both machines were the ancestors of most personal computers in use today, crucially demonstrating that the PC platform could evolve over time rather than having to be completely replaced with a new model every couple of years. And although the PC/XT and Portable were not the first PCs, and now very much obsolete, they were highly significant in developing the market we see today.

Image credits:
Dmitry Brant via Wikimedia Commons - CC BY-SA 4.0
ctgreybeard via Flickr - CC BY-SA 2.0

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