The Z-80 SoftCard is a plug-in Apple II processor card developed by Microsoft to turn the computer into a CP/M system based upon the Zilog Z80 central processing unit (CPU). Becoming the most popular CP/M platform and Microsoft's top revenue source for 1980, it was eventually renamed the Microsoft SoftCard, and was succeeded by Microsoft's Premium Softcard IIe for the Apple IIe.
Developer | Microsoft |
---|---|
Release date | 1980 |
Operating system | CP/M |
CPU | Z80 |
Platform | Apple II |
Successor | Premium Softcard IIe |
Introduced in 1980 as Microsoft's first hardware product,[1] and bundled with the Microsoft BASIC programming language,[2] the Z-80 SoftCard is an Apple II processor card that enables the Apple II to run CP/M, an operating system from Digital Research. This gives Apple II users access to many more business applications, including compilers and interpreters for several high-level languages. CP/M, one of the earliest cross-platform operating systems, is easily adaptable to a wide range of auxiliary chips and peripheral hardware, but it requires an Intel 8080-compatible CPU, which the Zilog Z80 is, but which the Apple's CPU, the MOS Technology 6502, is not.[3] The SoftCard has a Zilog Z80 CPU plus some 74LS00 series TTL chips to adapt that processor's bus to the Apple bus. As CP/M requires contiguous freely usable RAM from address zero - which the Apple II doesn't have, since its own 6502 CPU's call stack and zero page and its text mode screen memory cannot be outside the lowest 4 KiB of RAM - addresses are translated in order to move reserved-RAM and non-RAM areas to the top of memory.[4]
The SoftCard was Paul Allen's idea.[5] Its original purpose was to simplify porting Microsoft's computer-language products to the Apple II.[6] The SoftCard was developed by Tim Paterson of Seattle Computer Products (SCP). SCP built prototypes,[7] Don Burtis of Burtronix redesigned the card, and California Computer Systems manufactured it for Microsoft.[8] Unsure whether the card would sell, Microsoft first demonstrated it publicly at the West Coast Computer Faire in March 1980.[2][6]
Microsoft also released a version for the Apple IIe, the Premium Softcard IIe. The card has functionality equivalent to the Extended 80-Column Text Card, including its 64 KB RAM, so would save money for users who wanted CP/M capability, additional memory, and 80-column text.[9]
The SoftCard's immediate success surprised Microsoft. Although unprepared to take orders at the West Coast Computer Faire, a Microsoft executive accepted 1,000 business cards from interested parties on the first day;[6] Compute! reported that the company was "inundated" with orders.[1] The SoftCard became the company's largest revenue source in 1980,[10] selling 5,000 units in three months at $349 each, with high sales continued for several years. For a while, the SoftCard was the single most-popular platform to run CP/M,[11] and Z-80 cards became very popular Apple II peripherals.[12] By 1981 Microsoft, Lifeboat Associates, and Peachtree Software published their CP/M software on Apple-format disks.[8]
Compute! witnessed the SoftCard's debut in March 1980 at the West Coast Computer Faire, calling it "an Apple breakthru".[1] InfoWorld in 1981 called the SoftCard "a fascinating piece of hardware". While criticizing the "computerese" of the CP/M documentation, the magazine wrote "if you need a lightweight, portable Z80 computer, the Apple/SoftCard combination is a perfect pair."[3] BYTE wrote, "Because of the flexibility that it offers Apple users, I consider the Softcard an excellent buy .. The price is reasonable, and it works".[8]
InfoWorld in 1984 also favorably reviewed the SoftCard IIe, approving of its ability to also replace the Extended 80-Column Text Card. The magazine concluded that it "is a good system among several good systems on the market", especially for those who wanted to run Microsoft BASIC or wanted functionality beyond CP/M.[9]
Following Microsoft's success, several other companies developed Z80 cards for the Apple II as well, including Digital Research with Apple CP/M and a CP/M card developed by Advanced Logic Systems named "The CP/M Card" (with a 6 MHz Z80 and 64 kB RAM) and Digital Research's CP/M Gold Card for CP/M Pro 3.0 (with 64 or 192 kB RAM).[13][14] Others independent designs came from Applied Engineering, PCPI (with their 6 MHz Appli-Card), Cirtech, IBS. There were also about a dozen SoftCard clone manufacturers.
It was one of the founders of Microsoft, Paul Allen, who hit upon the idea of putting a Z80 processor into the Apple.
Unsure of the demand for the product, Microsoft took a prototype to the last West Coast Computer Faire
They brought in Tim Paterson of Seattle Computer Products, located across Lake Washington, to try to build a card for the Apple that would let it run Microsoft's 8080 and Z80 software. They called it the SoftCard. Paterson did a series of prototypes before Don Burdis took over the project.