Thursday, October 22, 2015

Still debugging 2310 and 1053 virtual/mirror adapter operation


I did manage to wrestle a few minutes free at lunch and went into the workshop to test some more. I have found the condition causing my problems with the virtual 2310 disk drive, but the mirror 1053 driver continues to return nulls (which types as a period on a selectric).

When I blocked the code from pushing any XIO Write characters into the FIFO, the 1053 adapter returned the special code for empty buffer - that part works well. This points me at the retrieval logic which is intended to pop out the character and send it back to the PC.

The 2310 adapter is getting back a modifier value of 0x81 from the XIO Init Read instruction, which is pointing at sector 1 but requesting a verify read, which doesn't actually transfer any data. On the real drive, the sector is read and the checksums are verified, thus it is testing that the data does not have any errors, although it does not transfer any of those words into core. My logic is not doing the right thing when this happens, thus inducing the loop I am experiencing.

I ran out of time and hadn't broken through on either of the problems. It is hard to debug complex logic in short bursts with long intervals separating them.

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