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2.4.3 BCD (Binary-coded Decimal)
(1) Definition
BCD is a numeral system that uses four binary bits to represent the decimal digits 0 through 9.
The difference from hexadecimal is that BCD does not use letters A to F.
Table2.7 shows the numeric representations in BIN, BCD, and DEC.
(2) Numeric representation in BCD
Each register (such as the data register, link register) in the CPU module consists of 16 bits.
Therefore, the numeric values can be stored in each register are those in the range between 0 to 9999 in BCD.
Table2.7 Numeric representations in BIN, BCD, and DEC
DEC (Decimal)
BIN (Binary)
BCD (Binary-coded Decimal)
0
0000
0
1
0001
1
2
0010
10
3
0011
11
4
0100
100
5
0101
101
6
0110
110
7
0111
111
8
1000
1000
9
1001
1001
10
1010
1
0000
11
1011
1
0001
12
1100
1
0010
Carry
