collapseos/recipes/z80mbc2
..
Makefile
README.md
xcomp.fs

Z80-MBC2

The Z80-MBC2 combines a Z80 and an ATMEGA32A to provide a CP/m capable computing environment. It features a SD card bootloader which makes running Collapse OS on it rather simple.

Recipe

In this recipe, we're going to run Collapse OS on the Z80-MBC2, interfacing through its serial port. We're going to use the MBC's API to implement BLK on the SD card. (the BLK part isn't done yet. TODO)

Gathering parts

  • A Z80-MBC2 computer with its SD card module and a properly flashed "IOS" on the ATMega32A.
  • A FTDI-to-TTL cable to connect to the serial port.

Building the binary

Running make will yield os.bin which is what we want.

Running on the Z80-MBC2

Mount the SD card on your modern computer and copy os.bin as autoboot.bin, overwriting the binary that was previously there.

Put back the SD card in the Z80-MBC2 and power it up by connecting the FTDI adapter to it (red: VCC, black: GND, green: TX, white: RX).

The FTDI adapter will show up as something like ttyUSB0 (or ttyU0 on OpenBSD). Connect to it with screen or cu or whatever you like. Baud rate of the Z80-MBC2 appears to be hardcoded to 115200.

Then, enable IOS program selection by holding RESET and USER at the same time, wait 2 seconds, releasing RESET, wait 2 seconds, releasing USER. You should then be given a 1-8 choice, with 4 being "Autoboot". Type 4.

You are now in Collapse OS.