USER MANUAL

Chapter 7
The Parallel Port
7–4
Data Line Values (Binary)
Table 7.B shows the value of the data lines using binary data inputs.
Table 7.B
Binary Data Line Values
Data Line
Data Line
Value
Comments
D0 1 Least Significant Bit
D1 2
D2 4
D3 8
D4 16
D5 32
D6 64
D7 128
D8 256
D9 512 Most Significant Bit
The binary value of the data lines is the sum of the individual data lines: D0
+ D1 + D2 + D3 + D4 + D5 + D6 + D7 +D8 + D9 = Value
. For example: if
D0, D4 and D7 are at some voltage level, and the others are at ground level,
the value on the data lines is D0 + D4 + D7 = 1 +16 + 128 = 145.
Data Line Values (BCD)
In the BCD system, 4 bits represent one decimal digit. Table 7.C shows the
value of the data lines using BCD data inputs.
Table 7.C
BCD Data Line Values
Data Line
Data Line
Value
Comments
(Range = 0 to 399)
D0 1
D1 2
O
n
e
s
D
igi
t (0-
9
)
D2 4
O
n
e
s
D
igi
t (0-
9
)
D3 8
D4 10
D5 20
Te
ns
D
igi
t (0-
9
)
D6 40
Te
ns
D
igi
t (0-
9
)
D7 80
D8 100
n s igi 3
D9 200
Hu
n
dred
s
D
igi
t (0-
3
)
Using the Parallel Port