Re: 251101-01 Kernal ROM chip for SX-64 (UD3)

From: Marko Mäkelä (
Date: 2007-01-09 21:06:32

On Tue, Jan 09, 2007 at 06:07:27PM +0100, Nicolas Welte wrote:
> Now when I had another look, I remembered a strange story someone told me. 
> He replaced a 2332 with a 2532 in a SuperPET, and the 6809 CPU wouldn't 
> work, because the 2332 has two CS inputs, but the 2532 only one! So guess 
> what, same thing in the 4040! Both inputs used! So I added a circuit to the 
> drive and now it can also use 2532 EPROMs. Two RAMs were also damaged, 
> after I changed them the drive is alive again :)
> I made some pictures of the modification:

Neat! You could have saved me some time by telling where you added the
circuit.  Am I right that you installed a socket and a chip to the lower
right corner, right of UB2?  It's neat that all required signals were
available nearby.  Was it a completely empty socket (only Vcc and GND
connected)?  It's a pity that the consumer-grade Commodores did away
with this practice of having some prototyping area (or place for fixing
hardware bugs).


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