It can manage eight priority interrupts. This is equivalent to providing eight interrupt pins on the processor in place of INTR pin.
Features of 8259A
1.
It can manage eight priority interrupts. This is equivalent to providing eight
interrupt pins on the processor in place of INTR pin.
2.
It is possible to locate vector table for these additional interrupts any where
in the memory map. However, all eight interrupts are spaced at the interval of
either four or eight locations.
3.
By cascading nine 8259s it is possible to get 64 priority interrupts.
4.
Interrupt mask register makes it possible to mask individual interrupt request.
5.
The 8259A can be programmed to accept either the level triggered or the edge
triggered interrupt request.
6.
With the help of 8259A user can get the information of pending interrupts,
in-service interrupts and masked interrupts.
7.
The 8259A is designed to minimize the software and real time overhead in
handling multi-level priority interrupts.
Review Question
1. List the features of 8259.
Microprocessors and Microcontrollers: Unit IV: (b) Programmable Interrupt Controller (PIC) - 8259 : Tag: : Programmable Interrupt Controller (PIC) - 8259 - Features of 8259A