Atari Program Exchange (APX) was a division of Atari that distributed software for the Atari 8-bit family of home computers through a quarterly mail-order catalog. APX allowed all programmers, not just professionals, to submit their programs for commercial distribution. If selected, that program was added to the catalog along with the credit to that programmer.
The brain-child of Dale Yocum, the Atari Program Exchange started in February 1981. In 1982 it management was taken over by Fred Thorlin, who operated it until it closed. APX published quarterly catalogs until 1984, when new Atari CEO James J. Morgan closed down the mail-order division.
Two of the biggest APX hits were Eastern Front (1941) and Caverns of Mars. Both sold tens of thousands of copies and were eventually converted by Atari to game cartridge form. The source code for Eastern Front was also available as a separate purchase. A later hit was Dandy, which inspired the arcade game Gauntlet and became the home game Dark Chambers. Though APX was created to sell user-written software, Atari distributed several official arcade ports through APX: 1978's Avalanche, credited to Dennis Koble, who wrote the original arcade game, and 1982 platformer Kangaroo, which was uncredited.
When Atari first launched the Atari 8-bit family in late 1979, the company kept most of the hardware details secret. It intended to be the primary supplier of software for the platform, as had been the case with the Atari 2600 console. By the end of the first year on the market increasingly sophisticated applications from outside Atari were nonetheless becoming available. There were, however, a limited number of distribution channels at the time.
Dale Yocum approached Atari with the idea of setting up their own third-party publishing arm. With Atari's distribution capabilities the products would be seen by many more prospective customers, and at the same time, Atari would make money with every sale, money that would otherwise be lost. Chris Crawford later stated: