Hallo Ian and others, I have no experience with a C= harddisk at all but enough experiences in repairing 6502 based systems. The first question is: is there a schematic available at all??? If there isn't, then one thing that you, Ian, can do is making one by re-engeneering the boards you have. Drawing one by hand is enough as I'm willing to convert it using a schematic-program. Without a SCH you still can do a lot. At http://home.hccnet.nl/g.baltissen/debugger.htm you find a debugger (SCH is missing for the moment). The core of the design is a flipflop that enables you to step the processor. This little gadget alone enables you to see if the 6502 does a proper reset. If it does the addressbus must show $FFFC plus a byte on the addressbus. You need a multimeter to read the individual bits from the databus. Step the 6502 and read the next byte. The two read bytes nust give a valid address. If you read $FFFF for example, the ROM never has been accessed and you know that something is wrong with the addressdecoder. About the cut wires: find out what they connected. This info alone could give you a clue. If it is a clocksignal, address- or dataline, you can suspect sabotage. In other cases you simply need the SCH. ___ / __|__ / / |_/ Groetjes, Ruud \ \__|_\ \___| http://Ruud.C64.org Message was sent through the cbm-hackers mailing list
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