AX = 440Ch
BX = device handle
CH = category code
07h tape (ASPITAPE.SYS)
CL = function
01h "mtop" - perform tape operation
02h "mtget" - get tape status
03h ignore end-of-tape errors
04h enable end-of-tape errors
DS:DX -> parameter block (see below)
Return: CF set on error
AX = error code (see AH=59h)
CF clear if successful
DS:DX -> data block
Notes:  This device driver is a simple DOS interface to the Adaptec Advanced
SCSI Programming Interface (ASPI).  It provides the following device
names as access to the SCSI tape, 'RMTx' (rewind on close) and
'NRMTx' (NO rewind on close) where x can go from 0 to 3.  There may
also be the following names 'MTx' and 'NMTx' which default to 1024
byte blocks.  The names may also have a '$' appended to try and make
them unique from file names of 'RMT0' etc.
once opend these devices must be put into RAW mode

Format of mtop parameter block:
Offset  Size    Description
00h    WORD    operation code
00h "MTWEOF" - write an end-of-file record
01h "MTFSF" - forward space file
02h "MTBSF" - backward space file
03h "MTFSR" - forward space record
04h "MTBSR" - backward space record
05h "MTREW" - rewind
06h "MTOFFL" - rewind and unload
07h "MTNOP" - perform TEST UNIT READY
02h    DWORD   repetition count

Format of mtget parameter block:
Offset  Size    Description
00h    BYTE    ASPI host ID
01h    BYTE    SCSI target ID
02h    BYTE    SCSI logical unit number
03h    BYTE    device parameters
bit 0: drive must use fixed-block read and write
bit 7: drive is an ASPI device
04h    BYTE    current device state
bit 0: device currently opened in buffered mode
bit 1: drive currently opened in nonbuffered mode
bit 2: rewind drive on last close
bit 3: drive has been written on
bit 4: drive has been read from
bit 5: next read will return 0 bytes
bit 6: EOM will resemble EOF
bit 7: drive may be busy rewinding
05h    BYTE    unit number within driver
06h    WORD    fixed block blocksize
08h    BYTE    last SCSI status
09h    BYTE    last SCSI sense key
0Ah    WORD    last SCSI opcode (packed)
bits 0-7: SCSI operation (SCSI packet byte 0)
bits 8-10: SCSI flags (SCSI packet byte 1)
bits 11-12: ASPI "Direction Bits" (ASPI SRB byte 3)
0Ch    WORD    residual bytes from SCSI opcode

See also: 214402

21440C - Greg Shenaut ASPITAPE.SYS - INTERFACE