Int 21 Fn 4403  - Smartdrv.sys V3.x Only - Ioctl - Cache Control           [c]

   AX = 4403h
   BX = handle for device "SMARTAAR"
   CX = number of bytes to write
   DS:DX -> SMARTDRV control block (see #1210)

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 #1366 at AH=59h/BX=0000h)

Note:  NCache2 (from the Norton Utilities v8.0) attempts to support this
     interface, but does not do so correctly, often hanging the system;
     one should use the SmartDrive v4.x or NCache private interfaces
     (see INT 2F/AX=4A10h/BX=0000h,INT 2F/AX=FE00h/DI=4E55h)

See Also: AX=4402h"SMARTDRV",INT 2F/AX=4A10h/BX=0000h

(Table 1209)
Values for SMARTDRV 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

Format of SMARTDRV control block:
Offset Size    Description (Table 1210)
 00h   BYTE    function code (see #1209)
---functions 00h-03h,06h,07h---
 no additional fields
---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