When used with a handle for a file, this function always returns a ready status, even if the disk is full or no disk is in the drive.Returns a code indicating whether the device associated with a handle is ready for output.
Call with:
AH = 44H
AL = 07H
BX = handle
Returns:
If function successful
Carry flag = clear
and, for a device:
AL = 00H if device not ready
FFH if device ready
or, for a file:
AL = FFH
If function unsuccessful
Carry flag = set
AX = error code
Note:
When used with a handle for a file, this function always returns a ready status, even if the disk is full or no disk is in the drive.
Example:
Check whether the standard auxiliary device (usually COM1) can accept a character for output.
stdaux equ 3 ; standard auxiliary handle
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mov ax,4407h ; function & subfunction
mov bx,stdaux ; standard auxiliary handle
int 21h ; transfer to MS-DOS
jc error ; jump if function failed
or al,al ; test status flag
jnz ready ; jump if not busy
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