What is the standard hardware connector designation for the 25-pin parallel port interface used in IBM-compatible PCs?
Ch 09: Software Interrupts and DOS/BIOS Services
Covers IVT structure (256 vectors x 4 bytes each = 1KB), pushing flags and CS:IP during interrupt invocation, hooking existing software interrupts, and invoking DOS function calls for disk and character I/O.
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CS401 - Computer Architecture and Assembly Language Programming Examination Practice
Timed practice exam simulation for CS401 - Computer Architecture and Assembly Language Programming.
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Why are the CLI (Clear Interrupt Flag) and STI (Set Interrupt Flag) instructions necessary when hooking an interrupt vector in the Interrupt Vector Table (IVT)?
Provide valid 8088 assembly instruction(s) to read an 8-bit input value from I/O port address 0x312.
Provide valid 8088 assembly instruction(s) to write the byte value in register AL to I/O port address 0x12.
Provide concise answers for the following system programming questions:
1. Why is it necessary to disable hardware interrupts (`CLI`) when altering interrupt vectors or executing critical kernel dispatch operations via software interrupt `INT 80h`?
2. Why must interrupts be disabled (`CLI`) before attempting to modify the stack pointers (`SS` and `SP`)?
In the IBM PC/AT architecture, which Interrupt Request (IRQ) line on the primary Programmable Interrupt Controller (PIC) is used as the cascade interrupt for connecting the secondary PIC?
During hardware interrupt processing, who sends the End of Interrupt (EOI) command byte (0x20) to the Programmable Interrupt Controller (8259 PIC)?
How many total pins are present on a standard DB-25 parallel port connector?
On a standard 25-pin DB-25 parallel port connector, which range of pins is tied to electrical ground?
What priority level is assigned to the IRQ 0 (System Timer) interrupt line on the 8259 Programmable Interrupt Controller?