Chapter 6. System compatibility
4.Waits one I/O delay
5.Enables the interrupt through the Set Interrupt Enable Flag command
Hardware interrupt IRQ9 is defined | as the | replacement interrupt | level | for the cascad |
Program interrupt sharing is implemented | on IRQ2, interrupt hex 0A. | The | following processing | |
maintain compatibility with the IRQ2 | used by | IBM Personal 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 interrupt
3.When the interrupt occurs, the system microprocessor passes control to the IRQ9 ( interrupt handler.
4. This interrupt | handler performs | an EOI command to the second interrupt controller and |
to the IRQ2 | (interrupt hex 0A) | interrupt handler. |
5. This IRQ2 interrupt handler, when handling the interrupt, causes the device to rese request before performing an EOI command to the master interrupt controller that fini the IRQ2 request.
Hard disk drives and controller
Reading from and writing to the hard disk is initiated in the same way as in IBM Pe products; however, new functions are supported.
Software compatibility
To maintain software compatibility, the interrupt polling mechanism that is used by IBM P products is retained. Software that interfaces with the reset port for the IBM Pers
Software interrupts
With the | advent | of | software interrupt sharing, software interrupt routines must daisy | ||||||||||||
routine must check the function value, and | if | it is | not in | the range of function calls | |||||||||||
transfer | control | to | the next routine in the chain. Because | software | interrupts | are ini | |||||||||
address | 0:0 | before | daisy chaining, | check | for | this | case. | If | the | next routine | is | poin | |||
the | function | call | is | out of range, | the appropriate | action | is | to | set | the carry | flag | ||||
an | error | condition. |
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Machine-sensitive programs
Programs | can select | they must first identify the | machine | |
IBM | has | defined methods for uniquely determining | the specific machine type. The machin | |
can | be | found through Interrupt 15H, Return System | Configuration Parameters function | (AH)=C0 |
24 Technical Information Manual