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IA8237

Programmable DMA Controller

Copyright

© 1999, InnovASIC Inc.

Customer Specific IC Solutions

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

TIMING

AND

CONTROL

ADSTB

MEMR_n

MEMW_n

IOR_n

IOW_n

CS_n

READY

CLK

AEN

EOP_n

RESET

PRIORITY

ENCODER

AND

ROTATING

PRIORITY

LOGIC

HDLA

HRQ_n

DREQ0_n :

DREQ3_n

DACK0 :

DACK3

COMMAND

MASK

REQUEST

DECREMENTOR

TEMP WORD

COUNT REG

INC/DECREMENTOR

TEMP ADDRESS

REG

BASE

ADDRESS

BASE

WORD

COUNT

READ BUFFER

CURRENT

ADDRESS

CURRENT

WORD

COUNT

READ WRITE BUFFER

WRITE

BUFFER

READ

BUFFER

IO

BUFFER

TEMPORARY

STATUS

MODE

READ

WRITE

COMMAND

CONTROL

OUTPUT

BUFFER

IO

BUFFER

A0 : A3

A4 : A7

DB0 : DB7

16

16

INTERNAL DATA

BUS