HP8711A Unable to boot 3.54 Firmware

[remap128]

Hello guys,

I have just finished a hardware restoration of an vintage HP8711A network analyzer.

My target was to convert it to a 8712 to enable the vector features. I tried to update the FW to 3.54 version. But after firmware install from floppy, analyzer fails some self-test during the bootup, and stops with error message

"UNEXPECTED EXCEPTION VECTOR W/ OFFSET 002C"
SR = 0700
PC = 4017FFF0

After returning to FW rev 2.10, everything works fine, but i suggest that I would be unable to enable the vector features (using bootrom mod) with this FW.

Can anybody help me, please?

[rfdes]

If I remember correctly, you need to add more dynamic ram in order to use this version of firmware.

[scopeman]

Been there. Tried that.

If it is an early 8711A 2.10 may be the highest FW that the instrument can run. I had one of those.

Unfortunately the units with the older CPU won't support the Vector options. I sold mine and bought a HP8713C which I updated to a HP8714C as it had a LAN interface as well.

Does the CPU board have 31 pin SIMM's? If so it is an older CPU card. Also it is very picky about the type of SIMM's that work on the motherboard. IIRC the older CPU board used a 16 pin DIP for the GAL that is used to enable IBASIC as well. The newer card uses the larger 020 flash parts as well. The older unit uses 010 flash.

Even without the vector capability the HP8711A is still a nice instrument.

Also before you tried the update from 2.10 to 3.54 I hope that you backed up and then restored the cal constants. IIRC I think it warns the user about that but it has been 5 years or so since I had a HP8711A

Sam
W3OHM

P.S. you can find full documentation on the HP8711A including the CLIP (I scanned mine and donated it to Keysight for placement on their site.)

[picburner]

Some old 8711A mainboards refuse to work with highest FW also because of the jumper in the DSP section which does not use all the SRAM.
The one highlighted in the pic is in the correct position.