INT 21 - SMARTDRV.SYS - IOCTL - CACHE CONTROL
AX = 4403h
BX = handle for device "SMARTAAR"
CX = number of bytes to write
DS:DX -> SMARTDRV control block (see below)
Return: CF clear if successful
AX = number of bytes actually written
= 0000h if control block too small for given command
CF set on error
AX = error code (01h,05h,06h,0Dh) (see AH=59h)
SeeAlso: INT 2F/AX=4A10h

Format of SMARTDRV control block:
Offset  Size    Description
00h    BYTE    function code
00h flush cache
01h flush and discard cache
02h disable caching (flushes and discards cache first)
03h enable caching
04h control write caching
05h set flushing tick count
06h lock cache contents
07h unlock cache contents
08h set flush-on-reboot flag
09h unused
0Ah control full-track caching
0Bh reduce cache size
0Ch increase cache size
0Dh set INT 13 chain address
---function 04h---
01h    BYTE    write caching control action
00h turn off write-through
01h turn on write-through
02h turn off write buffering (also flushes cache)
03h turn on write buffering (also flushes cache)
---function 05h---
01h    WORD    number of timer ticks between cache flushes
---function 08h---
01h    BYTE    new flush-on-reboot flag (00h off, 01h on)
---function 0Ah---
01h    BYTE    full-track writes are
00h not cached
01h cached
---functions 0Bh,0Ch---
01h    WORD    number of 16K pages by which to increase/reduce cache size
---function 0Dh---
01h    DWORD   new address to which to chain on INT 13
Note:   the previous address is not preserved

See also: 214402

214403 - SMARTDRV.SYS - IOCTL - CACHE CONTROL