Mumbai University > Computer Engineering > Sem 5 > Microprocessor

Marks: 5M

Year: May 2016

The 8259 is a programmable interrupt controller designed to work with Intel microprocessor 8080 A, 8085, 8086, 8088. The 8259 interrupt controller can

1. Handle eight interrupt inputs. This is equivalent to providing eight interrupt pins on the processor in place of one INTR/INT pin.
2. Vector an interrupt request anywhere in the memory map. However, all the eight interrupt are spaced at the interval of either four or eight location. This eliminates the major drawback, 8085 interrupt, in which all interrupts are vectored to memory location on page 00H.
3. Resolve eight levels of interrupt priorities in a variety of modes.
4. Mask each interrupt request individually.
5. Read the status of pending interrupts, in service interrupts, and masked interrupts.
6. Be set up to accept either the level triggered or edge triggered interrupt request.
7. Mine 8259 as can be cascade in a master slave configuration to handle 64 interrupt inputs.

The 8259 is contained in a 28-element in line package that requires only a compatible with 8259. The main difference between the two is that the 8259 can be used with Intel 8086/8088 processor. It also induces additional features such as level triggered mode, buffered mode and automatic end of interrupt mode.