Shepardson Microsystems

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Shepardson Microsystems, Inc. (SMI) was a small company producing operating systems and programming languages for the Atari 8-bit and Apple II computer families. SMI is most noted for authoring Atari's BASIC and Disk Operating System (DOS) products.


Shepardson Microsystems was founded by Robert Shepardson in Saratoga Springs, New York.

Shepardson Microsystems and Apple[edit]

On April 10, 1978, Shepardson Microsystems signed a contract with Apple. For $13,000 -- $5,200 up front, and $7,800 on delivery, and no additional royalties—Shepardson Microsystems would build Apple's first DOS—and hand it over just 35 days later. For its money, Apple would get a file manager, an interface for integer BASIC and Applesoft BASIC, and utilities that would allow disk backup, disk recovery, and file copying. Apple provided detailed specifications, and early Apple employee Randy Wigginton worked closely with Shepardson's Paul Laughton as the latter wrote the operating system with punched cards and a minicomputer.[1] That deal enabled release and sales of the Apple II.

Shepardson Microsystems and Atari[edit]

Atari planned to follow up its successful Atari VCS computer game system with a more powerful home computer (The Atari 400 and Atari 800), to be introduced at the January 1979 Consumer Electronics Show. This required the development of a BASIC interpreter. A version of Microsoft BASIC for the MOS 6502 had been licensed for this purpose, but the task of retrofitting the code into an 8k cartridge proved too difficult to meet schedule. Consequently, Atari turned to Shepardson Microsystems, who proposed a new BASIC instead of using Microsoft BASIC. Atari proceeded to contract with SMI not only for Atari BASIC, but the Atari Disk Operating System (Atari DOS) itself. Development of both products were completed ahead of schedule.

In early 1981, SMI concluded that their BASIC and DOS products were not viable, and permitted them (with the Atari Assembler Editor product) to be purchased by Bill Wilkinson and Mike Peters, who formed Optimized Systems Software. The new company then proceeded to enhance the products and sell them as third-party applications.


When Shepardson Microsystems ported BASIC to the Atari, their work was so quick that they had it finished before the contract was signed — and the contract had room for a $1000 penalty or bonus if the work appeared after a date in April 1979. They already had it done by the December 28, 1978 delivery of the contract.


  1. ^ Terdiman, Daniel (2013-04-03). "The untold story behind Apple's $13,000 operating system". CNET. Retrieved April 4, 2013. 
  • Wilkinson, Bill (1983). The Atari BASIC Source Book. Compute! Books. ISBN 0-942386-15-9.

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