INT 2F,8 - DRIVER.SYS Support (Undocumented DOS 3.2+)

AH = 08

AL = 00 installation check

= 01 add new block device

= 02 execute device driver request

= 03 get drive data table list (DOS 4.0+)

DS:DI = pointer to drive data table (AL=01)

ES:BX = pointer to device driver request header (AL=02)

on return:

AL = 00 not installed, ok to install (AL=00)

= 01 not installed, do NOT install (AL=00)

= FF installed (AL=00)

ES:BX = updated device request header (AL=02)

- function 01 scans DOS's drive data tables and appends the new

data table to to the chain. All tables referencing the same

physical drive are updated