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

From: Scott McDonnell (
Date: 2007-01-09 04:59:11

I would definitely agree with that diagnosis. However, before you start
looking for a replacement, have you opened the SX-64 and made sure all
the chips are pushed into their sockets completely? The case of the
SX-64 is pretty good at twisting the boards and eventually popping chips
out of sockets. Especially after shipment!


-----Original Message-----
From: []
On Behalf Of B. Degnan
Sent: Monday, January 08, 2007 10:30 PM
Subject: WTD: 251101-01 Kernal ROM chip for SX-64 (UD3)

Hi - I am working on an SX-64 that has a blank screen upon boot up.  It 
will run some carts, but not all.  I cannot load diskettes, but the
does come on briefly upon start up like you would expect.  I was able to

load and play Jupiter Lander cart, and more importantly run the C64/C128

Diagnostic Dead Test Cart (part # 314139-01).  The diagnostic returned
page OK, Stack page OK, RAM and sound tests OK.  Interestingly I could
get a different diagnostic cart to load, the "Commodore C-64 Diagnostic 
Cartridge" P/N 314061-01.  This is a nice diagnostic cart because it has
SX-64 detection and diagnostic routine.  I have other carts like Pac Man

and Spy Hunter that did not load either.

According to the symptoms I have
indicate (but not conclusively) that the problem is with chip UD3 - the 
251104-01 Kernal ROM.

Is this chip interchangeable with a regular C-64 Kernal ROM?  I would 
think... maybe?  I know that there are versions of the chip and maybe
the newer C64's would have something compatible.  If so, what is the

Does anyone have a spare 251104-01 or the equivalent for trade/sale?  I 
have plenty of regular C64's and other systems that I can borrow from.


Bill Degnan

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