Z80-MBC2: An Easy to Build Retro Z80 Computer in SBC Form

The Z80 microprocessor designed by Zilog powered some notable business PCs back in the mid 70’s to early 80’s, including the Osborne 1, Epsom QX-10 and the TRS-80 (among a host of others). Surprisingly enough, the Micro-Professor MPF1 (code and assembly language training system), introduced in 1981 is still being manufactured (by Acer no less) for use with the Z80. With that in mind, you might* be able to use it with Just4Fun’s Z80-MBC2 SBC — a Z80-based PC that can fit in your pocket.

The Z80-MBC2 is actually an upgraded SBC of Just4Fun’s original breadboard MBC with an added SD disk emulator and 128Kb of RAM for the CP/M 3 or CP/M 2.2 operating system (AKA control program). It features an ATmega32A for the universal I/O subsystem (rolling as EEPROM), and also functions as a reset and 4/8MHz clock generator for the Z80 CPU.

The MBC2 SBC is even outfitted with 16X GPIO header and can use any standard SD and RTC modules if you choose to use them. Just4Fun describes his Z80-MBC2 as a development platform with four ICs, which the microcontroller uses to simulate the Z80 support chips.

“It is a complete development ‘ecosystem,’ and using the iLoad boot mode it is possible to 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).”

Of course, to do that, he flashed the ATmega with MightyCore to gain a bootloader and to make it Arduino-compatible, which can be programmed through the board’s ICSP port. Just4Fun’s Z80-MBC2 SBC is another project to make it through to the finals for the 2018 Hackaday Prize contest and is also open source, so all of the schematics and software are listed on Just4Fun’s page for anyone interested in building their own.