Introduction to 8259 (8259 Microprocessor) || Interrupt Handling || Bcis Notes

Introduction to 8259 (8259 Microprocessor)

8259 microprocessor is defined as a Programmable Interrupt Controller (PIC) microprocessor. There are 5 hardware interrupts and 2 hardware interrupts in 8085 and 8086 respectively. But by connecting 8259 with CPU, we can increase the interrupt handling capability. It combines the multiple 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 it from 5 to 8 interrupt levels.

• It can be programmed according to given interrupts condition and it can be provided either with level or edge-triggered interrupt level.
• It can be programmed either work in 8085 or in it.
• Individual interrupt bits can be masked.
• By conducting more 8259 we can get up to 64 interrupt pins.

Features of 8259 PIC microprocessor 

• Intel 8259 is designed for Intel 8085 and Intel 8086 microprocessor.
• It can be programmed either in level triggered or in edge-triggered interrupt level.
• We can mask individual bits of interrupt request register.
• We can increase interrupt handling capability up to 64 interrupt level by cascading further 8259 PIC.
• A clock cycle is not required.

Pin Diagram of 8259 

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