Re: DD2 & 3

From: Gerrit Heitsch <>
Date: Tue, 18 Jun 2013 19:47:31 +0200
Message-ID: <>
On 06/18/2013 07:38 PM, Jim Brain wrote:

> I guess, but dubious.  CBM could have just went and stuffed something in
> the address map that contradicted the 6821 address space.  IN any event,
> it was an academic question.  Interesting that they sourced a 6821
> instead of just adding a '574/'245 or something simple.

Replacing even a single port of a 6821 or a 6522 with TTLs only sounds 
simple until you think about what this would really mean. I'd say a 6821 
or 6522 needs less space on the PCB than even a limited port setup using 
TTLs in DIP that supports direction change of the data flow.

I once thought about what it would take to replace the 6529 (which is 
VERY simple) used in the 264 series with TTLs and gave up after 5 TTLs.


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Received on 2013-06-18 19:00:12

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