I'm considering building something like this as a quick / cheap way to get people familiar with Z80 programming.
Z80 Emulator for Raspberry Pi Pico and other RP2040 based MCU boards (https://github.com/djbottrill/rp2040_z80_emulator)
It could run on this $4.00 Raspberry Pi Pico RP2040 (https://www.adafruit.com/product/4864?gad_source=1&gad_campaignid=21079227318&gbraid=0AAAAADx9JvRA4ZaQ1qTvuAsCId632A5MX&gclid=EAIaIQobChMIrMD42v7nkQMVuzIIBR3--ynEEAQYBSABEgInmvD_BwE) from Adafruit.
That sounds pretty good. I am using RUNCPM (https://github.com/guidol70/RunCPM_RPi_Pico) on my PicoCalc (https://forum.clockworkpi.com/t/runcpm-for-picocalc/20459 (https://forum.clockworkpi.com/t/runcpm-for-picocalc/20459).) On the PicoCalc, it takes the normally 40-column screen and displays 80 columns on it - takes a bit of practice to get used to the squished characters, but that would not be any trouble with using a terminal emulator (minicom - https://en.wikipedia.org/wiki/Minicom (https://en.wikipedia.org/wiki/Minicom), or TeraTerm - https://en.wikipedia.org/wiki/Tera_Term (https://en.wikipedia.org/wiki/Tera_Term)) on just a plain Pico.
I was amazed at the amount of software included with RUNCPM. I have just started going over the drives (yes, on the SD card image - https://obsolescence.wixsite.com/obsolescence/multicomp-fpga-cpm-demo-disk there are five hard disk images (with may USER areas each,) with a huge number of programs. I mentioned to Marilyn that this would have been the collection of an extremely rich professional programmer back in the '70s.
You need to add an SD card socket (https://www.amazon.com/DIYables-Adapter-Arduino-ESP8266-Raspberry/dp/B0BXKLNN2L (https://www.amazon.com/DIYables-Adapter-Arduino-ESP8266-Raspberry/dp/B0BXKLNN2L), but that, with a breadboard and some hookup wires, would provide an entire usable Z-80 CP/M system. Looks like your suggestion; it would be about the cheapest you can get.
I've been taking a closer look at the version that you posted. I really like the V. 2.2 version implementing the telnet server over WiFi. That would be really cool, plus it implies that a WiFi network connection could be added to allow CP-Net (http://cpmarchives.classiccmp.org/cpm/Miscellany/cpnet.html) network access to other servers, and simple web pages.
I do like the N8VEM collection of disks for RUNCPM - that is a serious collection. I'm thinking that some/all of those programs may be able to be installed for that David Bottrill Z-80 emulator that you mentioned. I noticed that the A: drive on David's Git page is a hard drive (8 Megabytes,) but I could not see what all was on that image. Also, I have not seen how to add other drives, but you may be able to take some of the stuff from the N8VEM disks and copy them over.
Also, the newest version of RUNCPM for the PicoCalc (https://github.com/theflynn49/picocalc_runCPM/releases/tag/v1.5)allows a Pico 2(W) to run CP/M at 200MHz on the Pico - that translates to a 32Mhz(!) Z-80 clone. :o I'm almost afraid to try Ladders on the PicoCalc. ;D
I was thinking this would provide an easier path to messing around with the Z80 using modern hardware. While I don't have the time to explore it at the moment, I would be happy to fund such an endeavor, should someone want to pursue it. It could then be duplicated to open the door to others as well.
Quote from: Chris Savage on Dec 31, 2025, 09:05 AMI'm considering building something like this as a quick / cheap way to get people familiar with Z80 programming.
Z80 Emulator for Raspberry Pi Pico and other RP2040 based MCU boards (https://github.com/djbottrill/rp2040_z80_emulator)
It could run on this $4.00 Raspberry Pi Pico RP2040 (https://www.adafruit.com/product/4864?gad_source=1&gad_campaignid=21079227318&gbraid=0AAAAADx9JvRA4ZaQ1qTvuAsCId632A5MX&gclid=EAIaIQobChMIrMD42v7nkQMVuzIIBR3--ynEEAQYBSABEgInmvD_BwE) from Adafruit.
If the ZX80/81 are Z80 based, in theory this could be modicied to work on the ZX80/81.
Quote from: JKnightandKARR on Jan 01, 2026, 08:14 PMIf the ZX80/81 are Z80 based, in theory this could be modicied to work on the ZX80/81.
Yes, and there are several projects that do this. @ikjordan has a GitHub page (https://github.com/ikjordan/picozx81?tab=readme-ov-file) with one. His (hers?) works on several platforms, one of which is less than $25 from Pimoroni (https://www.pishop.us/product/pimoroni-pico-vga-demo-base (https://www.pishop.us/product/pimoroni-pico-vga-demo-base).)
But, if you let go of the ZX-81 format, and just use a serial terminal on your PC, you can get full Z-80 experience from just the Pico, a breadboard, a micro-USB cable and some hook-up wires (and optionally an SD card socket.) Of course, you won't get the single-key BASIC, the low-rez graphics nor the ZX gaming experiences with these projects. You also won't have a true Z-80 hardware system - but if that is not so important, these projects will be cheaper.