Ok, I searched the forum but can't seem to find anything to help me with this so I'll try my luck by asking.
I have this Mac/65 cartridge that one day suddenly failed to work. When I insert the cart the computer directly goes to the self test screen when no disk is connected. The computer is a 130XE and works fine with other cartridges, I also tested the cart with other Ataris and the result is the same.
I've just got a programmer recently and dumped the Mac/65 ROM and tried it in Altirra. Everything works fine there, so the EPROM is not defective or erased (it was my first suspect). I checked the resistor and the two caps on the PCB and they are OK. That leaves the two NOR gates and the flip-flop chip as possible suspects. I can certainly try replacing them, but is there any way to test the existing chips to see which one is actually defective, or is there a possibility of something else being wrong?
EDIT: I found this link which is useful in testing the 74LS02.
I have this Mac/65 cartridge that one day suddenly failed to work. When I insert the cart the computer directly goes to the self test screen when no disk is connected. The computer is a 130XE and works fine with other cartridges, I also tested the cart with other Ataris and the result is the same.
I've just got a programmer recently and dumped the Mac/65 ROM and tried it in Altirra. Everything works fine there, so the EPROM is not defective or erased (it was my first suspect). I checked the resistor and the two caps on the PCB and they are OK. That leaves the two NOR gates and the flip-flop chip as possible suspects. I can certainly try replacing them, but is there any way to test the existing chips to see which one is actually defective, or is there a possibility of something else being wrong?
EDIT: I found this link which is useful in testing the 74LS02.