Z80-MBC2

Development version

I forked from upstream to document my BIOS development in CPM_3_Custom_BIOS. My target is the addition of a 2nd serial interface via the I2C port of the AVR chip. The serial module is inspired by the idea of eightbitswide, but I'll implement it gapless into the BIOS as AUX device.

I edit the source code on my Debian Linux and build directly on the CP/M system via MAKE.COM. Files are transfered between Linux and CP/M with lrzsz and XM.COM, using the xmodem protocol.

The current status is documented in an own README document, Highlights:

• Original BIOS source code in Z80 syntax (*.MAC) builds a working CPM3.SYS.
• MAKEFILE allows the faster build that translates only changed parts.
• CHARIO.MAC provides two new physical devices SIOA and SIOB.
• S220718-R290823_IOS-Z80-MBC2.ino provides I/O commands for communication and controlling.
• Makefile allows the compiling of the *.ino via arduino-cli tool.

The development process is discussed in detail in this (German) forum thread Z80 MBC 2 - Aufbau und Inbetriebnahme.

Original README file from upstream

The Z80-MBC2 is an easy to build Z80 SBC (Single Board Computer). It is the "evolution" of the Z80-MBC (https://hackaday.io/project/19000-a-4-4ics-z80-homemade-computer-on-breadboard), with a SD as "disk emulator" and with a 128KB banked RAM for CP/M 3 (but it can run CP/M 2.2, QP/M 2.71, UCSD Pascal and others).

It has an optional on board 16x GPIO expander, and uses common cheap add-on modules for the SD and the RTC options. It has an "Arduino heart" using an Atmega32A as EEPROM and "universal" I/O emulator (so a "legacy" EPROM programmer is not needed).

It is a complete development "ecosystem", and using the iLoad boot mode it is possible cross-compile, load and execute on the target an Assembler or C program (using the SDCC compiler) with a single command (like in the Arduino IDE).

Project page: https://hackaday.io/project/159973-z80-mbc2-4ics-homemade-z80-computer

Latest IOS revision: IOS S220718-R290823