The RC2040

Continuing from Emulating a Z80 RC2014 with CPM and IDE drives via an SD card here..


What is a Rc2040

The RC2040 is an emulated RC2014 (a build your self Z80 computer). But this one is entirely contained within a RP2040 (Raspberry Pi PI Pico) processor.

On the RC2040 you can Run any RC2014 Stock ROM image. including Basic and various Z80 monitors and CPM monitor. (except RomWBW there isn’t enough RAM)
RC2014 Rom Image details are here

Details on running the various RC2014 ROM based programs are here

Emulated ROM and RAM is a bit weird, because internally it’s all actually RAM, but the RC2040 allows a user definable area of RAM that is read only, or no ROM at all.

It also allows loading of RC2014 ROM images (rather than programming ROMS or EPROMs) directly from the attached SD card.

With CPM the RAM is more interesting, as CPM starts running from a ROM, but when it loads, the ROM is switched out so it can use the full 64K RAM. This is achieved in the RC2040 by simulating the RC2014 RAM/ROM card that allows an IO port to “swapout” or disable the ROM

Running the CPM monitor from the ROM, allows you to run any CPM-80 compatible program. There are hundreds out there and they include BASIC, Infocom Adventures (Zork, Hitchhikers) Wordstar, Startrek this list is endless.

CPM of course requires disk drives. These are emulated in file(s) on the SD card. The format is similar to the format used in the RC2014 CF card module (and with some simple changes, It will also work with the same CF images).

Instead of the CF format, the RC2040 uses a .img format, this makes it directly compatible with the CPM images from the RC2014 web site. But for CPM to work we also need a drive geometry structure which matches the .img, this is provided with an additional .id file.

The img format gives 128M of drive space, Split into drives from A-P

The img file system also makes it directly compatible with CPM Disk Manager which allows you to directly write into the CPM img file from your computer, which saves a lot of time when transferring software to your RC2040

The RC2014 uses its serial port to talk to the world. The RC2040 has the ability of using either its own USB embedded serial port, or a physical serial port similar to the RC2014’s this is selectable (see ini file settings )

The RC2040 also allows you to run with two different serial port configurations ACIA and SIO. Unfortunately you need a different ROM and CPM bios to work with each serial port type. Hence the selection in the Github SD card section. (again this is selectable via ini file settings.)

The CPM IDE images come with a few CPM programs to get you started. Anything ending in .COM will run directly from CPM. anything with a .BAS extension needs you to run basic first (c:MBASIC) then load the program (load “programname.BAS”) and then run.

More details on running CPM are here

Get You started. ( a work in progress..)

A complete kit of parts for the RC2040 is available here from Extreme Kits