Re: Microcontroller "PEEKing" into C64 memory?

From: Jim Brain <>
Date: Thu, 21 Jan 2016 18:41:18 -0600
Message-ID: <>
The idea is easy, but the TTL to do it is not.

Since I've already got my CPLD stuff on the bench, let me see if I can 
help you out there.

But, you would prefer, no doubt, something that plugs inside the case, 
not hang off the exp port.  Stuffing it under an IC inside the unit, and 
then sucking a IO select from somewhere would be ideal.

My first thought would be the SID (R/W line, some address lines, data 
lines, phi, pwr, gnd), but other places might be even better.  If you 
wanted to use the SID space, you have 3 registers there that conflict 
with nothing else:


You could do something like:

$1d = register
$1e = value

That would give access to a max of 256 LEDs, or you could do something 
more esoteric.

A CPLD could get you 8-10 registers in that fashion, if that's of interest.


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Received on 2016-01-22 01:00:11

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