Building a HP35 scientific calculator clone

[olekgr]

It's nice to present this project - Building a HP35 scientific calculator clone with a Z80 cpu from scratch.



But without using emulators, HP microcode etc. I have always wanted to rewrite original algorithms, created by David S. Cochran.
As the original HP35 was built 50 years ago, this is a good time to do the same :-)

Everything (hardware, software, source code, working gerbers etc) is on my github page:

https://github.com/olekgr/HP-35_Z80

I hope this project will be interesting for someone.

[EdS2]

Very nice! Thanks for sharing your code too!

[Roland57]

Great job, especially using the original algorithms !! Does your hp35 even exhibit the ln 2.02 bug ? :-)

Roland

[Chr Yoko]

Great work !
So you programmed the whole simulator under Z80 assembly language 8-)
(8 bits)
Looking at your schematic , it is quite inspiring too.

[redglyph]

That's impressive, thanks for sharing!

My first reflex would be indeed to use an FPGA, but it's not as fun as using the real Z80 and logic ICs. I used to love this CPU assembly language!

[Required]

Wow. Great work.
Love the assembly - reminds me of the coding I did as young.

Thank you for sharing!

[eshazen]

Very nice! I also built an HP-25 replica using a Z80 but I run the HP microcode in a C emulator. Your software is much more impressive.

My project: https://github.com/eshazen/retro-25