2020-06-23 03:32:50 +10:00
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# PC/AT
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2020-06-13 04:01:24 +10:00
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2020-06-23 03:32:50 +10:00
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PC-compatible machines need no introduction. They are one of the most popular
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machines of all time. Collapse OS has a 8086 assembler and has boot code
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allowing it to run on a PC/AT-compatible machine, using BIOS interrupts in
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real mode. Collapse OS always runs in real mode.
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In this recipe, we will compile Collapse OS and write it to a USB drive that
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is bootable on a modern PC-compatible machine.
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## Gathering parts
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* A modern PC-compatible machine that can boot from a USB drive.
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* A USB drive
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* qemu for emulation
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## Build the binary
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Running `make` in this folder with yield:
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* mbr.bin: a 512 byte binary that goes at the beginning of the disk
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* os.bin: 8086 Collapse OS binary
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* disk.bin: a concatenation of the above, with `blkfs` appended to it starting at
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`0x2000`.
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`disk.bin` is what goes on the drive.
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This binary has `BLK` and `AT-XY` support, which means you have disk I/Os and
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can run `VE`.
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## Emulation
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You can run the built binary in qemu using `make emul`.
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## Running on a modern PC
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First, copy `disk.bin` onto your USB drive. For example, on an OpenBSD machine,
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it could look like:
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doas dd if=disk.bin of=/dev/sd1c
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Your USB drive is now BIOS-bootable. Boot your computer and enter your BIOS
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setup to make sure that "legacy boot" (non-EFI boot, that is, BIOS boot) is
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enabled. Configure your boot device priority to ensure that the USB drive has
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a chance to boot.
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Reboot, you have Collapse OS. Boot is of course instantaneous (we're not used
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to this with modern software...).
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