INT 21,44,7 / IOCTL,7 - Get Output Status

AH = 44h

AL = 07

BX = handle

on return

CF = 0 if successful

= 1 if error

AX = error code if CF set (see ~DOS ERROR CODES~)

AL = 00 if ready (files), or not ready (char devices)

= FF ready (files or char device)

- indicates if a device or file is ready for output

- files always return ready, character devices don't