On Dec 3, 2018, at 10:55 PM, Alexander Pierson via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> wrote: In regards to 6502 variations in Atari machines, I found the bookmark detailing the specifics of "Sally", the 6502C: https://www.atarimax.com/jindroush.atari.org/achsally.html
Yeah, Sally was just a 6502 with the ability to halt the CPU via address line. This is beacuse the 8bit ataris all shared memory with the ANTIC chip and for it to read memory and build it's display lists it needs exclusive use of the bus and ram and needed a way to halt the cpu. The Atari CPU spends 40% of it's time halted as ANTIC does it stuff for the screen... think how much faster the systems would be if they just had non-shared ram. Which is exactly what Jay Miner did with the Amiga... -andyD