Re: 8520/21

From: Jim Brain <>
Date: Thu, 05 Mar 2015 12:36:21 -0600
Message-ID: <>
On 3/5/2015 12:25 PM, Gerrit Heitsch wrote:
> Well, the way it looks with MOS means that the lower last number is 
> the chip that was done first, just like the 6520 and the 6522.
> So they had that 6526 in NMOS and when the Amiga design came around 
> ('85), they wanted a CIA for it as well but decided against the 
> TOD/RTC from the original design, probably wanting the plain counter 
> instead. 
This is what makes no sense.

Hey, we're building a new PC.  Let's see, we have a steady source of CIA 
chips we could use.  Uh, no, let's go to *ALL* the trouble to tape out a 
new IC, drop the TOD clock, go to a new process, and test it all and run 
through 4 revs just to get it working.

That is nuts.  The 6526 variant was speced at 2MHz, just pull it out of 
the parts bin and use it.  Why go to all the trouble to create a new 
IC.  That makes no sense at all.

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Received on 2015-03-05 19:01:30

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