Click above to get retro games delivered to your door ever month!

INT 2F - Multiplex - 4DOS.COM v2.1+
        AX = D44Dh
        BH = function
            00h installation check
                Return: AX = 44DDh
                        BL = minor version number
                        BH = major version number
                        CX = PSP segment address for current invocation
                        DL = 4DOS shell number (0 for the first (root) shell,
                             updated each time a new copy is loaded)
            01h (internal) terminate current copy of 4DOS
            02h ???
                DX = ???
            03h EXEC program
                CX:DX -> EXEC record
            FEh deallocate shell number (passed through to root shell)
                ???
            FFh allocate shell number (passed through to root shell)
Note:   bug in v3.00 will crash system if unrecognized value in BH

Format of EXEC record:
Offset  Size    Description
 00h    WORD    offset of ASCIZ program name in same segment as EXEC record
 02h    WORD    offset of DOS commandline in same segment as EXEC record
 04h    WORD    segment of environment for child process (see INT 21/AH=26h)