HP-25 DIY with Z80

[eshazen]

Sorry for the long absence and not answering... challenging times.

Some people ask about keycaps. Search "Cherry MX relegendable" on e.g. Amazon.
Here is one seller, though they seem to be out of the 1x1 clear style right now.
The tops pop off and you just insert your own paper legend.

X-keys Keycap Cherry MX Compatible (Single, Purple, 10 Pack)
by P. I. Engineering
Learn more: https://www.amazon.com/dp/B00FZGETOM/ref...tFbEBMZQ6N

[eshazen]

I needed a new one for my office, and for variety I decided to use VFD displays.
It has a new power supply PCB at the back to provide the 1.2V @ ~1A and 25V for the VFDs and handle power sequencing.

I used Microchip HV5812 drivers for the VFDs which was quite straightforward.
All docs updated on github: https://github.com/eshazen/retro-25

[BobVA]

Nice! Thanks for the update!

[mpark]

Eric presented his calculators at the HPCC 2020 virtual conference. If you missed it, here's his presentation on youtube: https://youtu.be/Dise2HRakZ4?t=10213. Hopefully the timestamp works, but if not, skip to 2:50.

Great job, Eric!

[Eric Rechlin]

Direct link here to his talk:

https://www.youtube.com/watch?v=w87x0tetvFI