8259 Programmable Interrupt Controller (PIC)
Intel 8259 is aProgrammable Interrupt Controller (PIC). There are 5
hardware interrupts and 2 hardware interrupts in Intel 8085 and Intel 8086
microprocessors respectively. But by connecting Intel 8259 with these
microprocessors, we can increase their interrupt handling capability. Intel
8259 combines the multi-interrupt input sources into a single interrupt output.
Interfacing of single PIC provides 8 interrupts inputs from IR0-IR7. For
example, Interfacing of 8085 and 8259 increases the interrupt handling
capability of 8085 microprocessor from 5 to 8 interrupt levels.
Features of Intel 8259 PIC are as follows:
1. Intel 8259 is designed for Intel 8085 and Intel 8086 microprocessor.
2. It can be programmed either in level triggered or in edge triggered
interrupt level.
3. We can mask individual bits of interrupt request register.
4. We can increase interrupt handling capability upto 64 interrupt level by
cascading further 8259 PICs.
5. Clock cycle is not required.
