82C37 datasheet(13/34 Pages) OKI

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¡ Semiconductor

MSM82C37B-5RS/GS/VJS

Symbol

Pin Name

Input/Output

Function

End of Process

EOP

Input/Output

EOP is active-low bidirectional three-state signal. Unlike other

pins, this pin is an N-channel open drain. During DMA operations,

a low-level output pulse is obtained from this pin if the channel

word count changes from 0000H to FFFFH.

And DMA transfers can be terminated by pulling the EOP input to

low level. Both of these actions are called terminal count (TC).

Hold Request

HRQ

Output

HRQ is active-high signal used as an output of hold request to

the CPU for system data bus control purposes. After HRQ has

become active, at least one clock cycle is required before HLDA

becomes active.

Address Enable

AEN

Output

AEN is active-high ouput signal used to indicate that output

signals sent from the MSM82C37B-5 to the system are valid.

And in addition to enabling external latch to hold the eight higher

order bits of the transfer address, this signal is also used to

disable other system bus buffers.

DMA Acknowledge

0 - 3 Channels

DACK0 -

DACK3

Output

DACK is output signals used to indicate that DMA transfer to

peripheral devices has been permitted. (Available in each channel.)

Although these pins are switched to active-low when reset, they

can be programmed to become active-high.

Address 0 - 3

A0 - A3

Input/Output

A0 - A3 is bidirectional three-state signals used as input signals

for specifying the MSM82C37B-5 internal register to be accessed

by the CPU during idle cycles, and as an output the four lower

order bits of the transfer address during active cycles.

Address 4 - 7

A4 - A7

Output

A4 - A7 is three-state signals used as an output the four higher

order bits of the transfer address during active cycles.

Note that there is no DACK output signal during memory-memory

transfers.

When internal or external EOP is generated, the MSM82C37B-5

terminates the transfer and resets the DMA request.

When the EOP pin is not used, it is necessary to hold the pin at

high level by pull-up resistor to prevent the input of an EOP

by error. Also note that the EOP function cannot be satisfied in

cascade mode.

Memory Read

MEMR

Output

MEMR is active-low three-state output signal used as a control

signal in reading data from memory during read transfers and

memory-memory transfers.

Memory Write

MEMW

Output

MEMW is active-low three-state output signal used as a control

signal in writing data into memory during write transfers and

memory-memory transfers.

Address Strobe

ADSTB

Output

ADSTB is active-high signal used to strobe the eight higher order

bits of the transfer address by external latch.

PIN FUNCTIONS (continued)

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