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Radio Shack’s introduction of the Color Computer 3 introduced extensive changes to the Color Computer design. Gone were the 6847 VDG and 6883 SAM, functionally replaced and enhanced with the TCC1014 Advanced Color Video Chip (ACVC) which most folks reference as the GIME. Other additions included an additional 64kB of …

Now that we’ve learned a bit about how the 6809E wants to be treated during a direct memory access (DMA) request, we can put all we’ve learned into action. But, before we launch into the details, let’s address some questions that arose during previous article discussions: Some asked why the …

Picking up from last time, we were able to successfully place a byte into the internal CoCo memory from the cartridge port without the use of the CPU by utilizing a direct memory transfer procedure. However, after the transfer, BASIC programs would stop with errors at times, machine language programs …

As referenced in http://www.go4retro.com/2020/02/26/direct-memory-access-possibilities-on-the-tandy-color-computer/, I am attempting to coax some direct memory access functionality from a TANDY Color Computer. I’ll be utilizing a TANDY Color Computer 1 for initial testing, as I feel it most closely matches the Motorola 6809 reference architecture and this year is the 40th anniversary of …

As part of my continuing efforts to understand direct memory access (DMA) capabilities of various 80’s home computer systems, I decided I should figure out what, if any, DMA capabilities are possible on the TANDY Color Computer systems. There are 3 essential models in the lineup, though from a technical …