The BCD Number System
The Binary Coded Decimals (BCD) are exactly that, decimals (base 10) that are coded in the binary (base 2) format. Each decimal can be coded in the binary format and below is a table showing the conversions. Notice that the decimals are converted using a 4bit binary code.
Using the table below, we will convert the decimal number 529 to BCD. 5 in 4 bit binary is 0101, 2 in 4 bit binary is 0010 and 9 in 4 bit binary is 1001. Putting this together we get the following BCD number (notice the space between each coded decimal number):
Answer: 0101 0010 1001BCD = 529 (decimal)
Binary Coded Decimals (BCD)
| Decimal # | 8's | 4's | 2's | 1's | Totals |
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| 0 | 0 | 0 | 0 | 0 | 0+0+0+0=0 |
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| 1 | 0 | 0 | 0 | 1 | 0+0+0+1=1 |
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| 2 | 0 | 0 | 1 | 0 | 0+0+2+0=2 |
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| 3 | 0 | 0 | 1 | 1 | 0+0+2+1=3 |
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| 4 | 0 | 1 | 0 | 0 | 0+4+0+0=4 |
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| 5 | 0 | 1 | 0 | 1 | 0+4+0+1=5 |
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| 6 | 0 | 1 | 1 | 0 | 0+4+2+0=6 |
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| 7 | 0 | 1 | 1 | 1 | 0+4+2+1=7 |
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| 8 | 1 | 0 | 0 | 0 | 8+0+0+0=8 |
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| 9 | 1 | 0 | 0 | 1 | 8+0+0+1=9 |
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