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PCL-720
Programming
The Counter latch command is used to read back the value of a counter without
disturbing the count in progress.
M2-0 : Select the operating mode
M2
--0
0
X
X
1
1
M1
--0
0
1
1
0
0
M0
--0
1
0
1
0
1
Mode
---0
1
2
3
4
5
See Section 4.3.3. for the definition of each mode.
BCD : Selects binary or BCD counting
BCD
---0
1
Type
----------------------Binary counter l6-bits
BCD counter
If the modulus is set to be binary, the count can be any number from 0 up to
65,535. If the modulus is set to be BCD (binary coded decimal), then the count
can be set as any number from 0 to 9,999.
4.3.3. Mode Definitions
The definitions of the six operating modes are described here. Refer to the
data sheet of the 8253 for more details.
Mode 0 : Interrupt on Terminal Count
The output will be initially low after the mode set operation. After the
count is loaded into the selected count register, the output will remain