INT 21 - DoubleDOS - INSTALLATION CHECK/PROGRAM STATUS
AX = E400h
Return: AL = 00h if DoubleDOS not present
= 01h if running in visible DoubleDOS partition
= 02h if running in the invisible DoubleDOS partition
SeeAlso: AX=F400h

See also: 21E5

21E400 - DoubleDOS - INSTALLATION CHECK/PROGRAM STATUS