Why Apple was right and IBM was wrong

Stephen Withers
Thursday, 25 September 2008 13:56

Opinion and Analysis

The main barrier was the BIOS - a ROM chip containing a bunch of low-level routines that the software would use to communicate with the hardware. But a BIOS isn't particularly complicated, so it wasn't too difficult to use clean room techniques to produce a functional equivalent.

That involved forming two teams of programmers. One looked at the IBM BIOS (the source code was published by IBM) and produced a functional specification. The other team - who could all swear that they'd never seen the source code or examined the BIOS - worked from the specifications to produce equivalent code.

There was only 8K of code in the original BIOS, so it wasn't a huge task.

And in any case, it wasn't immediately obvious that IBM compatibility as opposed to MS-DOS compatibility was required, and so other companies came out with not very compatible models such as the DEC Rainbow and the Sirius-1. It was only when software that required true IBM compatibility became popular (eg, Lotus 1-2-3) that the market coalesced around what became known as industry-standard architecture.

As far as I'm aware, it was never IBM's intention to let other companies clone the PC, it was just that the design decisions made by the company meant they couldn't stop it happening.

Both IBM and Apple encouraged third-party manufacturers to produce peripherals and software for their computers, but Apple made it a lot harder for would-be cloners by using custom chips and putting more code into ROM (64K in the original Macintosh - eight times that of the IBM PC that appeared two years earlier).

Copyright protection meant other companies couldn't simply duplicate the ROM, and the additional complexity made it a bigger challenge to duplicate it. By the time court cases established that the Apple II ROM was protected, interest in that computer was fading.

These days, Apple's code is all in the operating system, and that allows Mac OS X to run on generic hardware as demonstrated by various enthusiasts as well as companies such as Psystar, even if such use is forbidden by the licence terms.

So if IBM did the right thing and Apple was wrong, riddle me this, Batman: which company is still in the PC business? Please read on.