
Operation Theory
•
47
M2, M1 & M0 - Select Operating Mode ( Bit 3, Bit 2, & Bit 1)
M2 M1 M0 MODE
0 0 0 0
0 0 1 1
x 1 0 2
x 1 1 3
1 0 0 4
1 0 1 5
BCD - Select Binary/BCD Counting ( Bit 0)
0
16-BITS BINARY COUNTER
1
BINARY CODED DECIMAL (BCD) COUNTER (4
DIGITAL)
Note: The count of the binary counter is from 0 up to 65,535 and the count
of the BCD counter is from 0 up to 9,999
Mode Definitions
With the 8254, six operating modes can be selected:
•
Mode 0
: Interrupt on Terminal Count
•
Mode 1
: Programmable One-Shot.
•
Mode 2
: Rate Generator
•
Mode 3
: Square Wave Rate Generator
•
Mode 4
: Software Triggered Strobe
•
Mode 5
: Hardware Triggered Strobe
Detail description of these six modes can be found in the Intel Microsystems
Components Handbook Volume II Peripherals.
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