Action! (programming language)

Action! is a procedural programming language and integrated development environment written by Clinton Parker for the Atari 8-bit computers. The language, similar to ALGOL, maps cleanly to the MOS Technology 6502 of the Atari computer without complex compiler optimizations. Fast execution speed of the resulting programs was a key selling point.

Parker, working with Henry Baker, had previously developed Micro-SPL, a systems programming language for the Xerox Alto. Action! is largely a port of Micro-SPL concepts to the Atari with changes to support the 6502 processor and the addition of an integrated fullscreen editor and debugger.

Action! was distributed on ROM cartridge by Optimized Systems Software starting in 1983. It was one of the company's first bank-switched 16 kB "Super Cartridges". The runtime library is stored in the cartridge; to make a standalone application requires the Action! Toolkit which was sold separately by OSS.

Action! was used to develop at least two commercial products—the HomePak productivity suite and Games Computers Play client program—and numerous programs in ANALOG Computing and Antic magazines. The editor inspired the PaperClip word processor. The language was not ported to other platforms.

The assembly language source code for Action! was made available under the GNU General Public License by the author in 2015.