HOST SOFTWARE INTERFACE
Reset and Interrupt 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 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.
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