Z-80 SoftCard

From Wikipedia, the free encyclopedia

This was a plug-in card, supplied by Microsoft for use with the Apple II personal computer.

The Z80 SoftCard had a Zilog Z80 CPU.

It enabled the Apple II to run the CP/M operating system, developed by Digital Research, which was at the time an industry standard operating system for running business software on small computers.

This CP/M capability conferred by the Z80 SoftCard transformed the Apple II a viable platform for running a much broader range of business software applications than had been possible up on the Apple II until that point.

It may not be entirely unreasonable to claim that the Z80 SoftCard may have been perhaps the single most significant piece of computer hardware ever developed (certainly in the microcomputer era) because it seems to be the only product which would have prompted IBM to consider Microsoft, who were at the time exclusively a programming language vendor which had never developed an operating system before, as a contender for providing an operating system for their forthcoming IBM PC when Digital Research themselves did not offer CP/M to IBM for this purpose.

The extent to which IBM's decision to approach Microsoft for the provision of the IBM PC operating system (a requirement which Microsoft did indeed eventually supply and which was called PC-DOS) might have been influenced by the Z80 SoftCard, remains tantalisingly undocumented, but as a persuasive case for this outcome, the SoftCard is unrivalled, simply because of the fact that the feat of being able to run, by means of a surprisingly simple installation, the CPU of one type of computer inside a computer which was using a completely different CPU, running a completely different operating system, seemed at the time to be an extraordinary achievement.

As a result of this 'impression of operating system mastery' which the Softcard conferred upon Microsoft (especially in the eyes of IBM) it would have seemed inconceivable to IBM that a firm that was capable of delivering such a remarkable achievement was not at least as capable of delivering a perfectly serviceable CP/M-like operating system which could be used for IBM's Personal Computer.

Who, so the logic of the circumstances would seem to imply, would be expected to be more capable of delivering an operating system with 'CP/M capabilities' (i.e., suitability for running business software applications) but running on a different CPU to the CPUs that CP/M ran on (CP/M ran on the Intel 8080 and the Zilog Z80 CPUs, whereas the IBM PC was going to use the Intel 8088 CPU) than the people who had already succeeded in getting CP/M to run on an Apple II (a computer with a MOS Technology 6502 CPU, a CPU which was in many ways more different from the processors which ran CP/M than the new IBM's CPU would be from the Intel 8080 and the Z80).

This apparent 'ability to create exotic operating system hybrids' evidenced by the Z80 SoftCard, might have even made Microsoft seem even more suited to develop the new operating system than Digital Research, despite the fact that Digital Research had developed the industry standard microcomputer operating system and Microsoft did not.

The question remains: where did Microsoft get the Z80 SoftCard from?

Microsoft certainly did not have a reputation for breakthrough hardware development up until this point.