HP-71B Auto on

[Sylvain Cote]

(02-07-2023 07:30 PM)J-F Garnier Wrote:  

(02-07-2023 04:30 PM)Sylvain Cote Wrote:  The behavior you are seeing are happening to me when I am pushing the HP-IL interface to its limits.

Although the problem of a HP-71B refusing to turn-off is easily reproducible (see my old post),
I don't know any sequence/condition that causes a HP-71B to wakeup after 4.5 h and stay on.
I would be interested to know how it can be reproduced.

Last year I did a lot of HP-IL testing while I was writing my HHC/Allschwil presentation on HP-IL asynchronous communication.

My main test setup was:

• 6 x HP-71B (1BBBB) with HP-IL module (1B)
• 2 x PIL-Box
• 1 x pyILPER (with virtual scope and virtual display)
• 1 x pyILPER (with virtual scope and virtual tape).
  

One of the tests involved saturating the HP-IL loop with asynchronous messages between all the 71Bs for an extended period of time. (~120 hours)

This specific test revealed two faulty HP-IL interfaces.
These interfaces were working correctly with light traffic but they failed under serious stress.
The symptom was that at some point the 71Bs who had the faulty interfaces were experiencing a memory lost after several hours in the tests.
Swapping interfaces between machines revealed that the issue was following the HP-IL interfaces and not the 71B computers.
Once those interfaces were removed, the communication worked for the duration of the test.

Like you mentioned in your old post, manually interrupting a 71B with the ATTN key with pending interrupts sometime cause the 71B to stay on.
If I remember correctly, it also happened when a faulty interface was resetting its 71B on the loop,
creating a broken loop message for the other 71Bs present that sometimes stopped the program while processing an IRQ.
When that happened, RESET HPIL normally worked but in some cases I had to do a hard reset to put back the 71B on its feet. (hard reset → off;unplug;on;wait;off;plug;on;reset)

Sylvain