Woodstock Display Upgrade (a sight for sore eyes)

[markhen]

What’s next?

I picked the HP-25 as the first target for this upgrade since it’s my all-time favorite calculator! I have an EXTENSIVE HP collection, and of course there are other models that I’d like to support:

- Panamatik HP-2xE – Bernhard’s amazing ACT was part of my inspiration for this project. I have upgraded calcs and HP-01 watches with Bernhard’s kits, and we collaborated on a couple of things previously. My upgraded HP-25 display does ALMOST work with the HP-25E ACT, but there are a few “wrinkles”… I intend to talk w/Bernhard to see if we can iron these out…

- HP-29C – Since the display module decodes the PRGM codes, some (easy) tweaks to the code will be required. From an initial investigation, I think there are also some slight differences in the display interface timing vs. the HP-25.

- HP-21, HP-22 - I think this module will work with both models, something I can test.

- HP-27 – I’m not sure if the HP-27 PMOS levels affect the display interface? Maybe someone here knows?

Although all the basic functionality is working, there is still some PCB cleanup, some code cleanup and a couple of residual bugs to chase, as always <sigh>