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

From: B. Degnan (billdeg_at_degnanco.com)
Date: 2007-01-09 04:29:45

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 light 
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 Zero 
page OK, Stack page OK, RAM and sound tests OK.  Interestingly I could not 
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 an 
SX-64 detection and diagnostic routine.  I have other carts like Pac Man 
and Spy Hunter that did not load either.

According to zimmers.net/commie/docs/sx64.txt the symptoms I have reported 
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 only 
the newer C64's would have something compatible.  If so, what is the chip 

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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