S-100 versus IBM PC

Created July 27 2022. This document copyright (c) Herbert R. Johnson 2022, with portions quoting materials which may have their own copyrights.


For some period of time, S-100 based computers (and other CP/M computers) of the late-70's into the late 80's, competed with the IBM-PC created in 1981. This Web page discusses that competition. As that history is decades old, much of it is lost. It's replaced with a "meme" that IBM and its PC, simply took over the microcomputing market in 1981. Or worse, that IBM "created" the first "serious" personal computer. That's simply unsupported history.

Of course, the people who "jumped ship first" from other computer lines to the IBM PC, often did well as the IBM product became adopted by well-established companies. The IBM brand (and marketing) made it easier for traditional companies (called "the Fortune 500" as listed in that popular business magazine) to adopt it, rather than adopt "hobby" or "industrial" class computers of the era. To the IBM-consulting people, who often wrote books and magazine articles about their success, it was clear that IBM (and so themselves) were "revolutionary". History is written by the winners.

However, actual history of the era, such as computing trade magazines, show that established non-IBM PC computers continued to be used and developed, for several years after the IBM PC introduction. And in fact, much early IBM PC software was simply prior software (often from the CP/M and 8080/Z80 world) that was re-assembled or re-compiled for the IBM PC's PC-DOS and its 8088 processor. Many of those competing and prior systems, had greater performance than current IBM PC's. It took a few years, from the 1981 introduction of the IBM PC, for popular CP/M software to "migrate" to the IBM PC platform. And it took some years for IBM PC's to add features and performance that exceeded earlier non-PC systems.

It's likely that non-IBM PC's finally fell into disuse, only when later IBM models were able to emulate CP/M and Z80's with faster performance than native systems. That likely occurred with the IBM AT product line with 80286 processors running over 10MHz clock rates. Even so, businesses and people continued to use their S-100 computers and other non-IBM-PC computers for many years. Why? Because they worked, they did their jobs, and new (IBM) computers were expensive.

In the mid-1980's and later, there was a market of IBM PC compatible products, some less compatible than others, but eventually becoming "100% PC compatible". PC compatibles became a consumer and business product at relatively low prices. By the 1990's inexpensive "PC clones" crashed the high-priced IBM PC brand market. That story is well-established computing history.

In short, the IBM PC was not a "revolution", but an "evolution" which took time. And by expanding acceptance of microprocessor based personal computing, the IBM PC for a time increased the microcomputer market for all participants. And even as the IBM PC architecture became a general standard by the late 1980's, even "cloned" as a cheaper Asian product; S-100 and other bus architectures (Multibus, STDbus, VMEbus) continued to fill niche markets in industrial controls and specialized high-performance digital products and systems.

But S-100 continued to provide a lower-cost and reasonable-performace point of entry for hundreds of computing products and services, into the 1990's. By personal count I am aware of likely 200 different companies and brands of S-100 computers from the mid 1970's up to 1990. The 1980's is full of history of the larger companies; the smaller ones are recorded in advertizing and small-journal articles, and their trail of digitized paper documentation, which are filling Web archives to the present day.

For the early history of the Altair/IMSAI S-100 bus, first created by MITS in 1975, check my S-100 origins Web page./a> For more information about the MITS Altair and other S-100 computers, check my S-100 home page.

- Herb Johnson

Herb Johnson
New Jersey, USA
email me @ my ordering Web page

Copyright © 2022 Herb Johnson