[Coco] Coco 4

[peak at mail.polarcomm.com]

Right.
I dont even want to try "cycle stealing DMA" at this time.
That is why I said I wont attempt an ISA adapter that uses 
cards with DMA.


---- Original message ----
>Date: Tue, 06 Jan 2004 17:15:57 -0500
>From: jdaggett at gate.net  
>Subject: Re: [Coco] Coco 4  
>To: CoCoList for Color Computer Enthusiasts 
<coco at maltedmedia.com>
>
>The 68x09 with internal clock is better suited for DMA 
operations. 
>With the "E" versions you have to use a psuedo DMA.
>
>The internal clock chip has a DMA pin when taken low 
suspends the 
>processor for 32 cycles. It checks every 32 clock cycles to 
see if 
>DMA is through. On the "E" You have to use the halt or do a 
cycle 
>stealing method. You have to treat teh DMA controller as a 
>coprocessor shareing the busses.
>
>james
>
>
>
>On 6 Jan 2004 at 11:03, Neil Morrison wrote:
>
>From:           	"Neil Morrison" <neilsmorr at hotpop.com>
>To:             	"CoCoList for Color Computer 
Enthusiasts" 
><coco at maltedmedia.com>
>Subject:        	Re: [Coco] Coco 4
>Date sent:      	Tue, 6 Jan 2004 11:03:40 -0800
>Send reply to:  	CoCoList for Color Computer 
Enthusiasts 
><coco at maltedmedia.com>
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>> 
>> I hadn't even considered DMA. The no-halt design of some 
controllers
>> would be nice however.
>> 
>> Neil
>> 
>> ----- Original Message ----- 
>> From: <peak at mail.polarcomm.com>
>> 
>> 
>> > The memory of an ISA card would be decoded using coco's 
CTS
>> > line and the I/O using coco's SCS line. If you really 
want an
>> > ISA card adapter for the coco I will see if I can design 
one
>> > at least as far as a schematic diagram. Warning* I wont 
even
>> > attempt using DMA though**. The hardware part of an ISA 
card
>> > adapter for 8-bit ISA cards that dont use DMA should not 
be a
>> > problem. I have been wanting to do this anyway.
>> > Note: Many ISA cards need a 14.318Mhz signal.
>> > The coco1 and coco2 have this frequency but coco3 does 
not.
>> 
>> > Eric
>> 
>> 
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