Disk Info Block
In the System16 Info Block, there is the entry 'Offset to the DiskInfoBlock (Relative to System16's Base Address)' at offset 90, that points to this block. It's a chained structure with information on all diskdrives accessable to the V2_OS. Each entry is 32bytes long and starts with one byte that holds the 'DiskNumber'. This is 0 for the first floppy, 80h for the first fixed disk, 81h for the second fixed disk etc. If this value is 0ffh, this indicates the end of the chain.

Ofs Size Description
0 1 DiskNumber
1 1 Reserved (for DiskType)
2 2 Maximum Cylinders
4 1 Maximum Heads
5 1 Maximum Sectors
6 1 DiskIndex in the 'Type Chain', like 'IDE3', or 'FLOPPY2' etc.
7 1 Reserved
8 8 Type BIOS, IDE, ATAPI etc. Padded with spaces !!!, left-alligned
16 8 Serving Module
24 4 DiskName like 'fd0',0 or 'hdb',0 etc. 0-Terminated
28 4 Reserved

This table can be displayed by using the 'disklist' command from the command-prompt.