Description
The basic layout of the 2600 is fairly similar to most consoles and home computers of the era. The CPU was the MOS Technologies 6507, a cut-down version of the 6502 that included less memory pins – 13 instead of 16 – to fit into a smaller 28-pin package. Smaller packaging is an important factor in overall system cost, and since memory was very expensive at the time, the small 4 KB memory space wasn't going to be used up anyway. In fact memory was so expensive they couldn't imagine using up even 4K, and when they got a deal on 24-pin connectors for the cartridge socket, they were only too happy to thereby limit the games to 2K.
Memory was so expensive that there was simply no way to have a "screen buffer", a portion of memory that holds the pattern to be drawn to the screen, at least not with the resolution they wanted. Instead they desided to have enough memory for only one line of the display at a time, when the TV completed drawing that line, the game was expected to quickly stuff the next line into the TIA while the TV was resetting for the next line.
It was a side-effect of this system, known to 2600 programmers as racing the beam, that the 2600 proved to be one of the most complex machines in the world to program. Nevertheless it was that same complexity that actually made the system incredibly flexible, and when authors discovered the "tricks" the games soon started to gain in power far beyond what the original designers had ever imagined.
Technical specifications
- CPU: MOS Technologies 6507
- Video processor: TIA
- Audio processor: TIA
- RAM: 128 bytes
- ROM cartridges: 4KB maximum capacity (32K+ with paging)
Third-party peripherals:
- Starpath Supercharger, a cartridge with a cassette player connector, giving 6 1/8 K storage capacity
See also:
- List of Atari 2600 games
- Jay Miner, designer of the Atari 2600 TIA chip
External links
- Interview with Joe Decuir (One of the designers of the Atari 2600 and the Atari 400/800 SIO. Currently he is one of the designers of USB)