Posted By
crock
on 2012-01-22
18:59:18
 |  Re: First Beta Release of Diag264 (0.2B)
I am assuming that your software implementation of the CPU models the fact that the CLK and DATA lines are read/write, and that setting CLK/DATA out high holds CLK/DATA in low, as it's buffered through an inverter on the MB, right?
The ATN line is only an output, so is not internally connected to any read line. To test ATNm the serial port loopback connector sends ATN back into the CLK input, so this step will fail on an emulator.
WRT to the user port, if you run this on a real C16, it will skip the test as it writes a sequence of values to $FD10 which will not be held as there is no register to hold them. You tend to get somewhat random values back, I assume from capacitance on the data lines, maybe as an artifact of the last instruction read?
The fact that YAPE shows this as a fail makes me think that even when you're emulating a C16, the 6529 is still there and thus storing the value. It then fails because the loopback between P4 and P0 is not present, hence a status of $10.
rob
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