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HOST SOFTWARE INTERFACE
6 – 6
Reset and Interrupt HandlingReset and Interrupt Handling
Reset and Interrupt HandlingReset and Interrupt Handling
Reset and Interrupt Handling
Reset HandlingReset Handling
Reset HandlingReset Handling
Reset Handling
One of three different conditions may cause a reset: power on, hardware reset or software reset. All three
cause the interface processor to initialize itself and the Task File registers of the interface. A reset also causes a
set of the Busy bit in the Status register. The Busy bit does not clear until the reset clears and the drive
completes initialization. Completion of a reset operation does not generate a host interrupt.
Task File registers are initialized as follows:
Error 1
Sector Count 1
Sector Number 1
Cylinder Low 0
Cylinder High 0
Drive/Head 0
Interrupt HandlingInterrupt Handling
Interrupt HandlingInterrupt Handling
Interrupt Handling
The drive requests data transfers to and from the host by asserting its IRQ 14 signal. This signal interrupts the
host if enabled by bit 1 (IRQ enable) of the Fixed Disk Control register.
Clear this interrupt by reading the Status register, writing the Command register, or by executing a host
hardware or software reset.