Int 15/AH=90h

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OS HOOK - DEVICE BUSY (AT,PS)

AH = 90h
AL = device type (see #00507)
ES:BX -> request block for type codes 80h through BFh
CF clear

Return:
CF set if wait time satisfied CF clear if driver must perform wait AH = 00h

Notes: Type codes are allocated as follows: 00-7F non-reentrant devices; OS must arbitrate access 80-BF reentrant devices; ES:BX points to a unique control block C0-FF wait-only calls, no complementary INT 15/AH=91h call. Floppy and hard disk BIOS code uses this call to implement a timeout; for device types 00h and 01h, a return of CF set means that the timeout expired before the disk responded.. 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

See Also: AH=91h - INT 13/AH=00h - INT 17/AH=00h - INT 1A

(Table 00507) Values for device type: 00h disk 01h diskette 02h keyboard 03h PS/2 pointing device 21h waiting for keyboard input (Phoenix BIOS) 80h network FBh digital sound (Tandy) FCh disk reset (PS) FDh diskette motor start FEh printer

Category: Bios - Int 15h - O

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