Posted By
crock
on 2011-02-10
05:05:48
 |  Re: cartridge programming
Yes, it is for the plus 4 and C16. I have around 8 boards at the moment, and while I've diagnosed them all, it required a *lot* of chip swapping and desoldering.
Yes TLC, that's exactly it. I had come to the same conclusions about the flip flops and was just seeing if there was some exploit out there.
If you have ram or kernal issues the most likely outcome is the ubiquitous blank screen. On a C64 this is easy to find with a dead test or some other cart which bypasses the kernal. For ram, i have a test routine that will run from rom making no use of either the zeropage or stack, and will indicate bad rams either via screen flash or any available I/O line to control LED's.
None of this is any use on a plus 4 though, because the rom/ram banking is all controlled through software and the cartridge selection goes through the kernal, which has already made use of the zeropage and stack before we get to the cartridge jumps. I have made it work by puting it on a rom that replaces the kernal chip but that's extra hassle and it means the kernal rom itself isn't tested.
It's also annoying that you can't bank the high area to ram leaving the low area to rom. I want to completely bypass the IRQ entry points in the kernal but I can't do this without copying my rom code into ram first.
rob
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