INT 15 - OS HOOK - DEVICE POST (AT,PS) AH = 91h AL = device type (see #00507) ES:BX -> request block for type codes 80h through BFh CF clear Return: AH = 00h Note: this function should be hooked by a multitasker to allow other tasks to execute while the BIOS is waiting for I/O completion; the default handler merely returns with AH=00h and CF clear SeeAlso: AH=90h