Shepardson Microsystems
| Company type | Private |
|---|---|
| Industry | Computer software |
| Founder | Robert (Bob) Shepardson |
| Headquarters | Saratoga Springs, New York , United States |
| Products | Apple II DOS, Atari BASIC, Atari DOS, BASIC interpreters for S-100 bus computers |
Shepardson Microsystems, Inc. (SMI) was a modest-sized computer programming firm established by Robert (Bob) Shepardson in Saratoga Springs, New York. The company concentrated on operating systems and programming languages tailored for CP/M, the Atari 8-bit computers, and the Apple II. Among its notable offerings were the initial Apple II disk operating system (DOS), Atari BASIC, and Atari DOS.
In 1981, Shepardson withdrew from the 8-bit software sector to resume independent consulting. At that time, two staff members purchased the rights to SMI's software and launched Optimized Systems Software, which remained active until 1988.
CP/M
SMI's early work involved creating a lineup of BASIC programming language interpreters designed for the expanding S-100 bus computer segment. Their inaugural product, Cromemco 16k BASIC, was aimed at Cromemco Z-series machines powered by the Z80 processor with 16 kB of memory.
With the transition from SRAM to DRAM and growing memory sizes, SMI developed the 26 kB Cromemco Structured BASIC and introduced a compact 12 kB CP/A Business BASIC.
Although Microsoft BASIC was widely adopted, SMI's BASIC variants drew inspiration from Data General Business Basic, contrasting with MS BASIC’s foundation in Digital's BASIC-PLUS. This distinction led to unique approaches in string manipulation and input/output processes, which later influenced their Atari language implementations.
Apple Computer
On April 10, 1978, Shepardson Microsystems secured a contract with Apple to produce Apple DOS, the company's first disk operating system. The agreement involved an upfront payment and further compensation upon delivery, without any royalty arrangements. Completed within just 35 days, Apple DOS featured a file management system, support for Integer BASIC and Applesoft BASIC, as well as utilities for disk backup, recovery, and file copying. Apple supplied comprehensive specifications; collaboration occurred between early Apple engineer Randy Wigginton and Shepardson’s Paul Laughton during development, which utilized punched cards and a minicomputer. This project facilitated the commercial release of Apple's Disk II drive.
Atari, Inc.
Following the success of its Video Computer System console, Atari, Inc. planned more advanced home computer models: the Atari 400 and 800, unveiled at the January 1979 Consumer Electronics Show. These systems licensed a version of Microsoft BASIC for the MOS 6502 CPU; however, fitting the interpreter into an 8k cartridge presented significant challenges.
Atari engaged Shepardson Microsystems (SMI) to assist with this porting effort. After encountering difficulties adapting Microsoft BASIC, SMI proposed developing an entirely new BASIC interpreter. Consequently, Atari contracted SMI to produce both Atari BASIC and the Atari Disk Operating System. SMI delivered their BASIC ahead of schedule, which earned them a $1000 bonus.
By early 1981, SMI considered their BASIC and DOS offerings no longer commercially viable and transferred ownership of these products along with the Atari Assembler Editor to Bill Wilkinson and Mike Peters. The pair established Optimized Systems Software, enhancing and distributing these as third-party software solutions.