The story
Optimized Systems Software was formed in early 1981 by Bill Wilkinson, Mike Peters, Paul Laughton, and Kathleen O'Brien. Laughton, the primary author of Atari BASIC, was still employed by Atari, Inc. at the time, and had permission to be involved with OSS from his manager. O'Brien wrote the Atari Assembler Editor for Atari. Laughton and O'Brien (married) were not as involved with the company and were bought out by Peters and Wilkinson.
OSS purchased Atari BASIC, Atari DOS, and Atari Assembler Editor from Shepardson Microsystems. The new company enhanced the programs, renaming them OS/A+ (the Disk Operating System), BASIC A+ (a disk-based language), and EASMD (an update to the Assembler Editor). OSS continued to work with Atari, Inc. (who had previously contracted with SMI) on enhanced products, most of which never reached the market.
OSS debuted at the West Coast Computer Faire in March 1981. The products they released over the next several years became respected among Atari programmers, particularly the MAC/65 assembler, the Action! programming language, and BASIC XL. In a 1984 interview, Bill Wilkinson said the company consisted of 15 people.
In January 1988, OSS merged with ICD (the makers of SpartaDOS and various Atari computer hardware add-ons). In 1994, Fine Tooned Engineering obtained limited rights to ICD's 8-bit products before disappearing.
From Wikipedia’s article on Optimized Systems Software, shared under CC BY-SA 4.0.3