HP41C with Rp Pico attached

[blackjetrock]

(03-15-2024 11:16 AM)floppy Wrote:  

(05-31-2023 06:27 AM)blackjetrock Wrote:  This is a project that I have been working on. It is a RP Pico sitting on the bus of an HP41C. It can trace the bus traffic and dump to USB and can also drive the bus and hence emulate a module or modules. It can also enter programs by pressing keys on the keyboard. There's a small OLED display that mirrors the LCD. It is very much a work in progress, so for instance, the entered programs aren't quite right and I've only emulated the MATH module.

https://github.com/blackjetrock/pico41.git

Andrew

Sniffing then extending an HP12C bus would make it interacting with the external world?

Hmm, in principle that could be done. I'm not very familiar with the 12C in terms of voltages and whether there is a bus inside that can be sniffed. There's a lot of emulators so I presume that the machine is well understood. If there is a sniff-able bus then yes, you could probably extend it with some scheme where a memory is re-purposed as a control and status location. Programs that wrote to that memory (a register, probably) would give instructions to the sniffer to do something, like send an I2C packet, or the sniffer would put the reply from external hardware in some other register.

I have done something similar with the casio FX502P, using the cassette port to interact with an attached processor.

https://youtu.be/JpELJASPR_0

I managed to attach a printer, which works by printing the program data that the 502P sends when saving a program to cassette tape.

https://youtu.be/e1qKueurD7A