a8237
®
Programmable
DMA Controller
Data Sheet
April 1999, ver. 1.01
Features
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a8237
MegaCore function implementing a programmable direct
memory access (DMA) controller
Optimized for FLEX
®
architecture
Provides four independent channels
Offers static read/write or handshaking modes
Includes direct bit set/reset capability
Uses approximately 1,201 FLEX logic elements (LEs)
Functionally based on the Intel 8237A and Harris 82C37A devices,
except as noted in
“Variations & Clarifications” on page 24
General
Description
The
a8237
MegaCore function implements a programmable DMA
controller, which controls memory-to-peripheral and memory-to-
memory data transfers and provides block memory initialization
capability. Four independently programmable channels are available in
the
a8237,
and DMA requests can be made via hardware or software.
Figure 1
shows the symbol for the
a8237.
Figure 1. a8237 Symbol
A8237
clk
hlda
ncs
neopin
niorin
niowin
ready
reset
ain[3..0]
dbin[7..0]
dreq[3..0]
adstb
aen
dben
dmaenable
hrq
neopout
niorout
niowout
nmemr
nmemw
aout[7..0]
dack[3..0]
dbout[7..0]
Altera Corporation
A-DS-A8237-01.01
5
ALTERA [ ALTERA CORPORATION ]
