08-05-2025, 01:24 AM
T is for TOS...
I did a little dive into the SIO and Joe Decuir was the smart guy at Atari. He said that in retrospect, he wanted a built in floppy drive on the 800 that was tied directly to the bus. The neat thing about the SIO, it was designed to be synchronous with a DATA IN/OUT clock. Although, that was never used and communication was done asynchronously and timing controlled by POKEY. Another interesting tidbit was that they capped communication speed to 19,200 bit/s even though they could go much faster. Supposedly speeds of 72,000 bit/s were achievable. The reason for capping at 19.2k was the analyzer equipment the engineer's at Atari were using couldn't handles speeds above 19.2k. That made me giggle...
I did a little dive into the SIO and Joe Decuir was the smart guy at Atari. He said that in retrospect, he wanted a built in floppy drive on the 800 that was tied directly to the bus. The neat thing about the SIO, it was designed to be synchronous with a DATA IN/OUT clock. Although, that was never used and communication was done asynchronously and timing controlled by POKEY. Another interesting tidbit was that they capped communication speed to 19,200 bit/s even though they could go much faster. Supposedly speeds of 72,000 bit/s were achievable. The reason for capping at 19.2k was the analyzer equipment the engineer's at Atari were using couldn't handles speeds above 19.2k. That made me giggle...