On 10/14/2013 12:22 AM, Baltissen, GJPAA (Ruud) wrote: > Hallo Jim, > > >> Strangely, if I reset the drive after disconnecting them (and connecting >> the two inputs of the '86 together, all works as expected. > That is correct. The data line should be (H) after a reset. The question is: what pulls it (L) after your disk access? Can only be the drive IMHO, acting on CA1 (you didn't mention disconnecting it). It's not low after disk access. In both situations, the DATA line is high. CA1 and PB7 are both disconnected from the PCB in both situations. Using this schematic for reference: http://www.commodore.ca/manuals/funet/cbm/schematics/drives/new/1541/tech/1541-35.gif PB7 and CA1 are disconnected, and I tie ATN IN to ATNA (tying ATN IN from the IEC port to pin 4 of the UG2 74LS86, which should render the output always low, making the UD1 7406 always high. I'll see if I can post some logic traces tomorrow night. I *think* it is because ATN IN floats high if I disconnect it, and the code handles that differently immediately after reset than after a successful disk access. I guess I'll need to tie it low when ATN is inhibited. Message was sent through the cbm-hackers mailing listReceived on 2013-10-14 07:00:18
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