[Color Computer] Re: [Coco] CoCo video?

Neil Morrison neilsmorr at hotpop.com
Mon Jan 30 01:00:23 EST 2006

I know everyone has their own idea about 'expanding' the Coco. I still like 
the idea of an expansion interface, like the old Model I, that sits under 
the monitor. I see a fast processor with a meg of ram and all the I/O you 
want, HD, FD, maybe even a USB. It would connect to the Coco via a cable and 
a connector in the ROMPak slot and would use the Coco for keyboard, video, 
and cassette say, but would do all the heavy processing. Good place to use a 
DMA and maybe a meg of ROM for OS-9 or whatever.


----- Original Message ----- 
From: <jdaggett at gate.net>

> Neil
> Yes there was. MC6844. This chip better interfaces with the MC6809 and
> not the MC6809E. The MC6809 has an input labled DMABREQ. Asserting
> this pin low will suspend the MC6809 execution for 16 cycles. Then the
> MC6809 will execute one cycle. Thus there is an alternating of 16 to one
> cycle ratio for DMA access.
> With some external logic this can be done with the MC6809E.
> james

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