[cctalk] Re: any COCO enthusiasts

The original coco had an MC6809E processor (a slight variation of the MC6809 processor), a MC6883 Synchronous Address Multiplexer and a MC6847 Graphics Chip. The 6883 SAM was the "glue" that provided all of the timing and address decoding for the entire system.  To reduce flicker the 6847 and 6809E memory accesses were alternate cycled.  This means that they used opposite edges of the Phase 1 clock  to access memory. However, this meant running the system at .8949 MHz.  The SAM had the ability to run the CPU at twice that speed but this resulted in the video being disabled. The 6883 SAM could address up to 96K of memory but to populate that much memory required after market modifications. There are many programs and peripherals available for the Color Computer.  The floppy disk system used 5 1/4" diskettes and could run operating systems like Flex, Star DOS and OS/9 Level 1.  I don't recall if OS/9 Level II was ported to the Color Computer. I believe there was even some kind of hard disk drive interface available, though not from Tandy IIRC. The audio cassette interface used 1200Hz/2400Hz tones to represent ones and zeros. There are many Color Computer enthusiast groups all over the country and people still make add-ons and software for it. Please just google Tandy Color Computer. On 1/23/2023 11:22 AM, Chris via cctalk wrote: