SYSTEM OVERVIEW
The 8259A Programmable Interrupt Controller manages interrupts for an Inte1386
DX
microprocessor system. Interrupts from
as
many
as
eight external sources are accepted
by
one 8259A;
as
many
as
64
requests can be accommodated
by
cascading several 8259A
chips. The 8259A resolves priority between active interrupts, then interrupts the proces-
sor and passes a code to the processor to identify the interrupting source. Programmable
features of the 8259A allow it to be used in a variety of
ways
to fit the interrupt require-
ments of a particular system.
1.10 INTEL PROGRAMMABLE LOGIC DEVICES
Intel manufactures a line of high speed PLDs (Programmable Logic Devices) specifically
designed for use with microprocessors such as the Intel386 DX. These devices called
j.LPLDs
(Microcomputer Programmable Logic Devices) include the 85C220 and the
85C508/85C509. Some of the design examples in this manual use these devices.
1-8