TU58 problems

tony duell ard at p850ug1.demon.co.uk
Sat Jan 16 15:52:39 CST 2016

> I can certainly understand that.  But a TU58 emulator could be a useful
> diagnostic tool.  Personally, I would try to get it working from the

Agreed. But a diagnostic tool is only useful if you can trust it. I suspect that if 
I tried to set up a TU58 emulator I would have problems due to my lack of
programming knowledge and thus would be wondering if my problems were
due to the emulator or the VAX CPU..

> Similarly, it could be a useful diagnostic tool to connect the real
> TU58 hardware to a known-working (presumably slightly more modern)
> machine to see if it's willing to work that way.

Yes. Does such a program exist? Something that will let me send commands 
to the TU58 and see what it sends back? Again I could write one, but then 
again I want to be sure that when it doesn't work it's a real problem with the

I've read and re-read the TU58 ROM source listings and AFAIK there is no way
it could send the result packets my serial comms analyser thinks it is sending. No
logical fault could cause it to drop the bytes it seems not to be sending. My guess is
that said analyser is not doing what I expect! See what I mean about diagnostic tools
that are unreliable...


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