Missile Command -- Repair Log and Notes

KI4SWY

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So, Working on a Missile Command, Got the funky thing going on, Can't scratch my head on it...


Using a Fluke 9010A + 6502 Pod.

Rom Tests OK.
Ram Tests Fail with DCD error ( memory written to one address is at at another address )..

So, Testing Further.

If you write 0xFF to 0x0000 & 0x0001 , and then write 0x00 to 0x0001, 0x0000 will now have 0x07

This repeats for all the ram memory. ( regardless if working ram, 2bit, 3bit color,etc )
 
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It almost appears that DEAD0 & DEAD1 are tied together for J4,K4,L4,M4,N4,P4

hmm... I will need to check the previous repair work under socket J4.

i bet the output of F3 is able to only drive the first 3 ram chips before the "Short" takes over.
 
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