More FPGA progress



Just some news for those interested :
A new HP86b+ in FPGA

Some more bugs but many progress ...



Looking very good!

My own recent FPGA project (RetroChallenge 2010 winner, "best hardware hack") was much less ambitious: implementing the old COSMAC ELF microcomputer from the Popular Electronics article in an FPGA. Runs 100 times faster than the original.

It's not really calculator related, but I do have CamelForth running on it, so at least it does RPN. :-)

Much thanks to Jim Donnelly, former HP Corvallis Division calculator engineer, for machining the aluminum front panel for me. Much thanks also Richard Ottosen and Jim Phillips, who also helped with the front panel. Richard recorded the demo video using my cell phone.

demo video

Blog entries



Back in the last 70s, I was a fan of the CDP1802 and the ELF. I built my own ELF, which is still operable today, with its eight toggle switches using DMA to initialize RAM from console (no ROM monitor needed), a speaker driven by Q, and so on. The original ELF had a couple of HP hex displays that were very nice but also expensive, so I resorted to standard 7-segment displays driven by Mitel 4368 decoders (if memory helps). I bought an 1861 for video, but never found time to put it to work. In fact, in the Memories section of the Museum, in an old article by me, there are photos of my ELF and also of a "chemical process monitor" I developed with the 1802. The fact that it was CMOS captured me, but not to the point of consuming all my hobby money; some was directed to my HP-41C and its accessories.

I would like to know more about your FPGA-based COSMAC, because I became a EE professor, and we have some courses here where the students replicate classic microprocessors using FPGA.

Best regards, congratulations, and thank you for the chance to refresh these memories!


Cool project! Thanks for letting us know. Those of us unable to solder may still use the Cosmac Elf Emulator and key in the dice rolling program.

Edited: 12 Aug 2010, 3:30 a.m.


I just placed an order for this board, for another project. Is your 85B emulator available for others to try out?

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