HP-65 goes on hold after reading a card

[teenix]

(11-15-2020 12:13 AM)albertofenini Wrote:  Hi everyone

this is a unit that we restored a while ago but never truly tested
Few days ago we replaced a coil following the advice of Teenix (thanks for help !) and fixed an issue that was causing the G segment to be always off (the related coil was open)

We discovered that when a card is read, a steady 0.00 appears, but when we try to execute the loaded program, the unit goes in a non responsive status.

With the diagnostic card, to name one, it happens just hitting the R/S key in order to start the test
With the Temperature Conversion, to name another, you can input a value and it locks immediately after that

When used for standard operations it works with no problem

I may be wrong but with a number on the screen just typed, pressing STO will make
a .00 appears after the digit, but then pressing RCL won't recall the number.

Thanks for any idea you may want to share in roder to possibly fix it
Let us know if we can upload anything that can be of help

Take care !

My emulator shows the entered number plus [00] on the display after STO is pressed if FIX 2 is selected.

Are you pressing (say) STO 5, then use RCL 5 to recall it.

Can you write a program and switch to RUN mode and execute it? Does it read with a known good CPU board?

If so, then problem could be the card reader, the CRC chip in the hybrid, the usual copper traces, connection from card reader to CPU board etc.

I guess invalid data could be read from the card which confuses the CPU board when the code tries to run.

cheers

Tony