At this point it is tempting to go into the software side of the development - but this is mostly Microsoft's, and in particular Bill Gates' story. Although Bill Gates claims the he influenced the design of the machine, this seems unlikely. The use of the 8/16-bit 8088 is a logical step for the time and according to sources was taken before Gates knew about the project.

The interesting part of the story is, of course, the meeting of the two cultures. Stuffy IBM and whiz-kid Microsoft didn't really seem likely candidates for a relationship and of course as it turned out in the long run they weren't! While they tried to make it work, the stories of IBM people turning up in tee-shirts and trainers to meetings that Microsoft people turned up to in blue suits make good telling.

A more serious problem was IBM's attitude to security. The prototype was supposed to be kept in a secure place and IBM inspectors visited Microsoft to make sure that the conditions were adhered to. Most of the time Microsoft managed to get wind of the impending visiting and get the machine back into its allocated room. Once, however, they were caught out with the prototype half way down a corridor while its programmers played catch.

When IBM finally introduced the PC the response wasn't what they expected. It wasn't really what anyone expected as the machine didn't look that good. IBM had forecast sales of 250,000 units over a five year period. They sold that many in the first few months. There were constant shortages of supply and even a black market at one point. They had managed to produce something that everyone wanted.

The IBM XT - the next model complete with optional hard disk.

IBM's open architecture policy certainly contributed to the success of the machine. Software became available very rapidly and so did hardware add-ons. However IBM didn't quite get it right. Because they had used off-the-shelf parts other manufacturers were able to build copies, or clones, of the machine. In the early days people at IBM didn't seem at all sure about what it was that belong to them. They tried to make it sound as if parts of the machine were proprietary to IBM. They even emphasised the difference between PC-DOS and MS-DOS when they were in fact the same software produced by Microsoft.

About the only part of the design that they could have claimed as their own was the BIOS - the code in the ROM that managed the hardware. This held up the clone manufacturers for some time but eventually they produced legal a BIOS ROMs by getting programmers to write it from scratch given only a functional definition and proof that there had been no access to IBM's code. Once the cloners got started the price fell.

A corner of the IBM PC (XT) mainboard - the copyright notice wasn't enough protection

IBM never really recovered from the shock of what happened. It must have felt like being mugged. Most of what it did after the PC looked very much like an attempt to get even. For example, when it designed the PS/2 range it made sure that it contained proprietary hardware and software. Any clone manufacturer who wanted to licence it had to pay back royalties on all of the PC machines they had built in the past - see what I mean about getting even! Today IBM doesn't make a personal computer at all.

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