Web site:
Origin: USA
Category: Game
Desktop environment: GUI
Architecture: Atari
Based on: Independent
Wikipedia:
Media: Install
The last version | Released: 1981
Atari OS – an operating system that came with the Atari 400 and 800 eight-bit computers. It took up 10k and ranged from $D800-$FFFF.
There are three known versions of the system:
– OS 255 – It named because in this version, address 65528 ($FFF8) contains the value 255 ($FF). It was created in April 1979. It was not intended for distribution, but several thousand ROM chips of this version were produced, some of which likely made it to market. In this version, the procedures for communicating with the tape recorder differ from later versions in terms of the pilot signal duration.
– Rev. A – According to “All About Cassette Tapes” from June 1979. Installed in early NTSC computers and all PAL computers. The system differs slightly between NTSC and PAL versions; the differences concern the procedures for counting elapsed time in communication with external devices. Address 65528 ($FFF8) is 221 ($DD) in the NTSC version and 214 ($D6) in the PAL version.
– Rev. B – From September 1981. Installed in later NTSC computers. Address 65528 ($FFF8) is 243 ($F3). The CPS SuperSALT cartridge from 1983—i.e., from the period after the end of production of the 400/800 series—does not contain the code responsible for detecting rev. B PAL system[5](it detects the other 3 versions as well as XL OS), which suggests that PAL rev. B was not available on the market.
