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MSM82C43

8/13

PIN FUNCTIONS

Pin

PROG

CS

P20 – P23

P40 – P43

P50 – P53

P60 – P63

P70 – P73

GND

Function

Clock input from MSM80C49. When PROG is changed from "H" to "L", MSM82C43 STARTS

operating in accordance with an order from MSM80C49.

Input for chip select. Outputs and internal status cannot be changed when CS is "H".

4-bit bidirectional I/O ports. When connected to P20 thru P23 of MSM80C49, direct data

transfer from port to accumulator and from accumulator to port is possible.

4-bit bidirectional I/O ports.

Data is latched statistically when output to ports, but is only valid while PROG is at "L" level

when input.

+5V power supply

GROUND

FUNCTIONS

Power-on reset mode

Upon powered on, ports to 7 are 3-stated, and 2 is put into an input mode.

Write mode

Execution of MOVDPp, A, ORLDPp, A, ANLDPp, and A by MSM80C49 enables direct output

of accumulator contents to ports 4 thru 7, and output to the ports after ORing or ANDing with

port data. The port data is latched statistically at this time and remains unchanged until

execution of the next instruction.

Read mode

Execution of MOVDA andPp results in data of ports 4 thru 7 being accepted by the accmulator.

Note that port data is valid only while PROG is at "L" level. When at "H" level, ports 4 thru 7 are

switched to tristate and port 2 is switched to input mode.

Address and instruction code

Instruction

Port

P23

P22

P21

P20

Read

Port 4

00

00

Write

Port 5

01

01

OR

Port 6

10

10

AND

Port 7

11

11