a8259
®
Programmable
Interrupt Controller
Data Sheet
July 1997, ver. 1
Features
s
s
s
s
s
s
s
Optimized for FLEX
®
and MAX
®
architectures
Offers eight levels of individually maskable interrupts
Expandable to 64 interrupts
Offers a flexible priority resolution scheme
Provides programmable interrupt modes and vectors
Uses approximately 399 logic elements (LEs) in FLEX devices
Functionally based on the Intel 8259 device, except as noted in the
“Variations & Clarifications” section on page 79
General
Description
The Altera
®
a8259
MegaCore
™
function is a programmable interrupt
controller. The
a8259
can be initialized by the microprocessor through
eight data bus lines (din[7..0] and
dout[7..0]),
and the
ncs, nrd, nwr,
int,
and
ninta
control signals.
Figure 1
shows the symbol for the
a8259.
Figure 1. a8259 Symbol
A8259
nMRST
CLK
nCS
nWR
nRD
A0
nINTA
nSP
CASIN[2..0]
IR[7..0]
DIN[7..0]
INT
CASOUT[2..0]
CAS_EN
DOUT[7..0]
nEN
Altera Corporation
A-DS-A8259-01
57
ALTERA [ ALTERA CORPORATION ]
