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====== Int 21H, AH=64H ======

===== Version =====

3 and higher

===== Brief =====

SET DEVICE DRIVER LOOKAHEAD FLAG

===== Family API =====


===== Input =====

  AH = 64h
  AL = flag
  00h (default) call device driver function 5 (non-dest read) before INT 21/AH=01h,08h,0Ah
  nonzero don't call driver function 5

  CX = 636Ch - Call OS/2 VDM function
  
===== Return =====

  Nothing (MS-DOS)
  CF set, AX=error code??? (DR DOS 5.0, which does not support this call)

===== Notes =====

This function is called by the DOS 3.3+ PRINT.COM. Under MS-DOS, this function does not use any of the DOS-internal stacks and may thus be called at any time, even during another DOS call
          
===== See also =====

AH=[[en:docs:dos:api:int21:01|01h]] - AH=[[en:docs:dos:api:int21:08|08h]] - AH=[[en:docs:dos:api:int21:0a|0Ah]] - AX=[[en:docs:dos:api:int21:5d:06|5D06h]]

===== Note =====

Text based on [[http://www.cs.cmu.edu/~ralf/files.html|Ralf Brown Interrupt List Release 61]]

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