Z-80 SoftCard

The Z-80 SoftCard was a plug-in card, supplied by Microsoft for use with the Apple II personal computer. It had a Zilog Z80 CPU plus some 74LS00 series TTL chips to adapt that processor's bus to the rather different bus system used in the Apple. The card was eventually renamed the Microsoft SoftCard.

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 and a large range of compilers and interpreters for several high-level languages on small computers. CP/M, one of the earliest cross-platform operating systems, was easily adaptable to a wide range of auxiliary chips and peripheral hardware, but it required an Intel 8080 compatible CPU, which the Zilog Z80 was, but which the Apple's main CPU, the MOS Technology 6502, wasn't.

This CP/M capability conferred by the Z80 SoftCard transformed the Apple II into 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.

The "SoftCard" was Paul Allen's idea^[1] and was developed jointly between Tim Paterson of Seattle Computer Products (SCP) and Bill Gates and Don Burtis of Microsoft, after SCP developed the initial prototypes. Microsoft received most of its revenue from selling language compilers and interpreters for CP/M systems at this time, which was before MS-DOS entered the market and became the company's best selling product. They hoped to broaden their customer base with this card.

A copy of the Microsoft BASIC programming language was also included in the Softcard package (and the BASIC license offering is likely to have played a significant part in Microsoft's initial motivation for their involvement in developing the SoftCard)

It was first demonstrated publicly at the West Coast Computer Faire in March 1980.

An immediate success, there were 5,000 cards purchased in the initial three months at $349 each, and the card sold well for several years. The SoftCard was the single most popular platform to run CP/M.^[1]

References

1. ^ ^{a b} William H. Gates IV Page Voteview.com

External links

• AppleLogic website, showing peripheral cards for the Apple II series of computers, including the Microsoft Softcard