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In reply to : Bret 'll have to hate FreeDOS mKEYB, too (Developers)

posted by Japheth Homepage, Germany (South), 18.05.2011, 06:47

> Most likely, but not necessarily. It is at least theoretically possible to
> flush the SMARTDRV caches with INT 15.4F even if you don't intend to
> reboot.

I don't think this idea will work - at least not when EMM386 is loaded. The MS tool:


   MOV AH,0D                 ; Disk Reset
   INT 21h                   ; causes SmartDrv 4.x to write cache
   MOV AX, 40                ; set up segment addressing
   MOV DS, AX
   DS:
   OR  BYTE PTR    [17],0C   ; equivalent of pressing CTRL+ALT
   MOV AX,4F53               ; Issue a "DEL" (53h = DEL scan code)
   INT 15h                   ; EMM386 sees this & shuts down
   DS:
   MOV WORD PTR [72],1234    ; Set REBOOT flag to Warm-Boot (0=cold)
   JMP F000:FFF0             ; Execute the internal restart routine


uses int 15.4F53 to "shut down" EMM386 ( note that int 21h is used to clear the cache ). If EMM386 detects int 15h.4f53, it will reboot immediately and won't return - because it could do this only if no EMS or UMBs are supplied - which is a very rare case.

---
MS-DOS forever!

 

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