8/19

¡ Semiconductor

MSM82C53-2RS/GS/JS

DESCRIPTION OF BASIC OPERATIONS

Data transfers between the internal registers and the external data bus is outlined in the

following table.

0

0

0

0

0

CS

Function

0

0

0

1

0

1

1

1

0

1

RD

0

0

0

¥

1

0

0

0

1

0

WR

1

1

1

¥

1

0

1

1

0

0

0

1

1

¥

¥

1

0

1

0

0

1

0

1

¥

¥

Data Bus to Counter #0 Writing

Data Bus to Counter #1 Writing

Data Bus to Counter #2 Writing

Data Bus to Control Word Register Writing

Data Bus from Counter #0 Reading

Data Bus from Counter #1 Reading

Data Bus from Counter #2 Reading

Data Bus High Impedance Status

¥ denotes "not specified".

DESCRIPTION OF OPERATION

MSM82C53-2 functions are selected by a control word from the CPU. In the required program

sequence, the control word setting is followed by the count value setting and execution of the

desired timer operation.

Control Word and Count Value Program

Each counter operation mode is set by control word programming. The control word format

is out-lined below.

SC1

SC0

RL1

RL0

M2

M1

M0

BCD

Select Counter

Read/Load

Mode

BCD