Hard Disk Drives And Controller; Machine-Sensitive Programs - IBM NetVista Technical Information Manual

following processing occurs to maintain compatibility with the IRQ2 used by IBM
computer products:
1. A device drives the interrupt request active on IRQ2 of the channel.
2. This interrupt request is mapped in hardware to IRQ9 input on the second
3. When the interrupt occurs, the system microprocessor passes control to IRQ9
4. This interrupt handler performs an EOI command to the second interrupt
5. This IRQ2 interrupt handler, when handling the interrupt, causes the device to

Hard disk drives and controller

Reading from and writing to the hard disk is initiated in the same way as in other IBM
computer products; however, new functions are supported.

Machine-sensitive programs

Programs can select machine-specific features, but they must first identify the
machine and model type. IBM has defined methods for uniquely determining the
specific machine type. The machine model byte can be found through Interrupt 15H,
Return Configuration Parameters function (AH)=(C0H).
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NetVista™ Technical Information Manual
interrupt controller.
(interrupt hex 71) interrupt handler.
controller and passes control to the IRQ2 (interrupt hex 0A) interrupt handler.
reset the interrupt request before performing an EOI command to the master
interrupt controller that finishes servicing the IRQ2 request.