On 10/17/2017 10:50 AM, Dominique Carlier via cctalk wrote: > Hi Chuck, > > Yes I understand well. But the fact that the machines Z80 based were all > equipped with this famous serial I/O channel A and B, I therefore > thought that the principle of verification of these channels would > probably be the same on this type of architecture (Z80+PIO+CTC+SIO). > Therefore, there should be probably more people able to give me some > useful information.
Perhaps, but we don't know exactly what surrounds the Z80 SIO, or exactly what the diagnostic is complaining about. Does your SIO have anything other than line drivers or receivers on its external interface? Some systems have programmable loop-back circuitry to enable the terminal to function to talk to itself and verify functionality. If you ignore the diagnostic message and feed the terminal some serial data, do the inputs on the SIO wiggle appropriately in response? In other words, is the data getting from the connector to the SIO chip? Troubleshooting is slow, methodical work. The SIO/DART chip itself is very simple--and most likely not the cause of the diagnostic failure. But writing your own diagnostic software can verify that. At least that's what I think from a few thousand km away. --Chuck
