IA8237 Datasheet, PDF (2/4 Pages) InnovASIC, Inc – Programmable DMA Controller

IA8237
Programmable DMA Controller
Page 2 of 4
Advanced Information Sheet
The IA8237 is a programmable direct memory access (DMA) mega-function designed to be
functionally equivalent to the Intel 8237A and Harris 82C37A devices. The A8237 controls data
transfers between memory and peripherals, memory-to-memory transfers, and block memory
initialization. Four independently programmable channels are available, and requests may be
generated via hardware or software.
A block diagram is shown in Figure 1.
Functional Block Diagram
Figure 1
EOP_n
RESET
CS_n
READY
CLK
AEN
ADSTB
MEMR_n
MEMW_n
IOR_n
IOW_n
TIMING
AND
CONTROL
DREQ0_n :
DREQ3_n
HDLA
HRQ_n
DACK0 :
DACK3
PRIORITY
ENCODER
AND
ROTATING
PRIORITY
LOGIC
DECREMENTOR
TEMP WORD
COUNT REG
INC/DECREMENTOR
TEMP ADDRESS
REG
IO
BUFFER
A0 : A3
16
READ BUFFER
16
READ WRITE BUFFER
BASE
ADDRESS
BASE
WORD
COUNT
CURRENT
ADDRESS
CURRENT
WORD
COUNT
COMMAND
WRITE
BUFFER
READ
BUFFER
INTERNAL DATA
BUS
OUTPUT
BUFFER
A4 : A7
COMMAND
CONTROL
IO
BUFFER
DB0 : DB7
MASK
REQUEST
READ
WRITE
STATUS
TEMPORARY
MODE
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