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@ -132,7 +132,7 @@ INT ($FC): Interrupt vector management functions |
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INTSET ($20): Set interrupt vector |
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BC=Function/Subfunction A=Result |
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HL=Interrupt Vector HL=Previous Vector |
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E=Interrupt Vector Table Position DE=Interrupt Routing Engine Address |
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E=Interrupt Vector Table Position |
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Set the Interrupt Vector for the specified Interrupt Vector Table Position to the |
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specified Interrupt Vector. The previous value at the specified table position |
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@ -151,28 +151,25 @@ INT ($FC): Interrupt vector management functions |
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must be saved and restored by the interrupt handler. |
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Interrupt handlers are different for IM1 or IM2. |
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For IM1: |
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The new interrupt handler is responsible for chaining (JP) to the previous vector |
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if the interrupt is not handled. The interrupt handler must return with ZF set |
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if interrupt is handled and ZF cleared if not handled. |
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if the interrupt is not handled. If the interrupt is handled, the new handler may |
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simply return (RET) with ZF cleared (NZ). |
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For IM2: |
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The interrupt handler requires an invocation stub separate from the actual interrupt |
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handling code. The stub must be: |
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The new interrupt handler may either replace or hook the previous interrupt |
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handler. To replace the previous interrupt handler, the new handler just returns |
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(RET) when done. To hook the previous handler, the new handler can chain (JP) |
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to the previous vector. Note that initially all IM2 interrupt vectors are set |
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to be handled as “BAD” meaning that the interrupt is unexpected. In most cases, |
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you do not want to chain to the previous vector because it will cause the |
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interrupt to display a “BAD INT” system panic message. |
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PUSH HL |
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LD HL,<adr of actual interrupt handler> |
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JP <adr of int routing engine> |
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When calling Set Interrupt Vector, the address of the stub must be provided for the |
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Interrupt Vector parameter. The address of the Interrupt Routing Engine will be |
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returned in DE and must be inserted into the stub code as indicated above. In the |
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case of IM2 mode interrutps, the actual interrupt handler should not chain to the |
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previous entry. The new interrupt handler must assume all responsibilities for |
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the specific interrupt slot being occupied. |
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The interrupt framework will take care of issuing an EI and RETI instruction. |
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Do not put these instructions in your new handler. |
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If the caller is transient, then the caller must remove the new interrupt handler and |
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restore the original one prior to termination. This is accomplished by calling this |
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@ -236,8 +233,9 @@ DEVICE ($06): |
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Serial Device Attributes Byte: |
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7: 0=RS-232, 1=Terminal |
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6: 1=Parallel Port |
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If Terminal, 3-0 is attached Video Unit # |
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If device is of type Terminal, bits 3-0 indicate attached Video Unit # |
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============== |
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Disk Functions |
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b1ackmai1er
6 years ago
GitHub