With the OS-9 system diskette in Drive 0, the DOS command boots the OS-9 Operating system.

DOS

NOTE: The DOS command only exists in Disk BASIC 1.1.

Disk BASIC 1.0 users had to load and run a boot / floppy speed test program manually to start OS-9.

The DOS command loads the content of diskette track 34 into memory starting at address $2600.

The loaded track data must start with the ASCII signature bytes 'OS' to be recognized as a valid boot track.

The next two bytes will be the address for Disk BASIC to branch to after loading the track, to start running the boot loader code itself.

See Disk BASIC Unravelled II, page B36, addresses $DF00 to $DF4B for the code implementing the DOS command.

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