Control Block Format (DOS 4.x):

% Offset Size Description

00 dword starting sector

04 word number of sectors to write

06 dword pointer to buffer

- writes disk sectors from buffer at DS:BX or DS:[BX+6]

- after calling this interrupt the flags register remains on the

stack and must be popped manually

- sectors are logical sectors starting at the beginning of a

logical disk; each DOS partition on a drive unit is considered

one logical drive and has it's own logical sector numbers with

track 0 starting at the first track in the partition

- this function uses logical drives, and is susceptible to ASSIGN

- physical sector numbers can be converted to and from DOS sector

numbers with the following formulas:

dos_sector = (sector - 1) + (head * sectors_per_track) +

(track * sectors_per_track * num_heads)

physical_sector = 1 + (dos_sector MOD sectors_per_track)

physical_head = (dos_sector / sectors_per_track) MOD num_heads

physical_track = dos_sector / (sectors_per_track * num_heads)

- see ~INT 13,STATUS~