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55 lines
2.1 KiB
Markdown
55 lines
2.1 KiB
Markdown
# Z80-MBC2
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The [Z80-MBC2][link] combines a Z80 and an ATMEGA32A to provide a CP/m capable
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computing environment. It features a SD card bootloader which makes running
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Collapse OS on it rather simple.
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## Recipe
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In this recipe, we're going to run Collapse OS on the Z80-MBC2, interfacing
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through its serial port. We're going to use the MBC's API to implement BLK on
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the SD card.
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### Gathering parts
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* A Z80-MBC2 computer with its SD card module and a properly flashed "IOS" on
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the ATMega32A.
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* A FTDI-to-TTL cable to connect to the serial port.
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### Building the binary
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Running `make` will yield `os.bin` which is what we want.
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### Running on the Z80-MBC2
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Mount the SD card on your modern computer and copy `os.bin` as `autoboot.bin`,
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overwriting the binary that was previously there.
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We also have to copy the blkfs over. This is done by using IOS' drive system.
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Each `DSxNyy.DSK` file on the card is a drive, each drive has 512 track of 32
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sectors of 512 bytes, so one drive is plenty for our needs. Collapse OS
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hardcodes drive 0.
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Each drive is part of a set. IOS theoretically supports up to 10 sets, but the
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binary shipped by default only accepts 4. You have to overwrite an existing set.
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I used set 3. So, copy `blkfs` to file `DS3N00.DSK`. If you want, you can change
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the name of the set by changing the contents of `DS3NAM.DAT`.
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Put back the SD card in the Z80-MBC2 and power it up by connecting the FTDI
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adapter to it (red: VCC, black: GND, green: TX, white: RX).
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The FTDI adapter will show up as something like `ttyUSB0` (or `ttyU0` on
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OpenBSD). Connect to it with `screen` or `cu` or whatever you like. Baud rate of
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the Z80-MBC2 appears to be hardcoded to 115200.
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Then, enable IOS program selection by holding RESET and USER at the same time,
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wait 2 seconds, releasing RESET, wait 2 seconds, releasing USER. You should then
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be given a 1-8 choice.
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You begin by selecting the proper disk set, which is through choice 8, then you
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select the Autoboot binary through choice 4.
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You are now in Collapse OS.
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[link]: https://hackaday.io/project/159973-z80-mbc2-a-4-ics-homebrew-z80-computer
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