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

jdaggett at gate.net jdaggett at gate.net
Mon Jan 30 13:07:18 EST 2006


Neil

I agree that there are many directions that one can go from the base of the Coco 3. My
opinion is that the Multipack interface is a limiting item. To realy go forward the Coco
expansion bus needs to be taken to 50 pins minimum. This can allow more decoded I/O
than what is presently available.

james

On 29 Jan 2006 at 22:00, Neil Morrison wrote:

To: "Coco on Yahoo" <colorcomputer at yahoogroups.com>
From: "Neil Morrison" <neilsmorr at hotpop.com>
Date sent: Sun, 29 Jan 2006 22:00:23 -0800
Subject: [Color Computer] Re: [Coco] CoCo video?
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>

> 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.

>

> Neil

>

> ----- 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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