Purpose
The 12B/14B line code is designed to provide a DC balanced encoding scheme for transmitting 12-bit data words over high speed serial links.
Encoding Algorithm
Like 8B/10B, the code table is split into two parts. The 7 least significant bits are encoded using a 7B/8B encoding table, and the 5 most significant bits are encoding using a 5B/6B table.
The 7/8 encoding is considered first, along with a running disparity count. The code is looked up in the 7B/8B table. Then it is optionally inverted if doing so would bring would bring the running disparity closer to 0. Some codes naturally have 0 disparity (4 ones and 4 zeros), and these are never inverted.
Then the 5/6 encoding is considered. The code is looked up in the code table, and then optionally inverted according to the following rules
- Attempt to balance the overall 14-bit code.
- If the selected 8-bit code has positive disparity, invert the 6-bit code if needed to achieve negative disparity.
- If the selected 8-bit code has negative disparity, invert the 6-bit code if needed to achieve positive disparity.
- Attempt to balance the running disparity
- If the selected 8-bit code has even disparity, invert by rules above based on the input running disparity rather than the selected 8-bit code disparity.
7B/8B Code Table
Name | In 7b | Out 8b | Out Disparity | Alt 8b | Alt Disparity |
D.0 | 0000000 | 01011000 | -2 | 10100111 | 2 |
D.1 | 0000001 | 00011001 | -2 | 11100110 | 2 |
D.2 | 0000010 | 00011010 | -2 | 11100101 | 2 |
D.3 | 0000011 | 00100011 | -2 | 11011100 | 2 |
D.4 | 0000100 | 01100100 | -2 | 10011011 | 2 |
D.5 | 0000101 | 10000101 | -2 | 01111010 | 2 |
D.6 | 0000110 | 10000110 | -2 | 01111001 | 2 |
D.7 | 0000111 | 10000111 | 0 | #N/A | 0 |
D.8 | 0001000 | 01101000 | -2 | 10010111 | 2 |
D.9 | 0001001 | 10001001 | -2 | 01110110 | 2 |
D.10 | 0001010 | 01001010 | -2 | 10110101 | 2 |
D.11 | 0001011 | 10001011 | 0 | #N/A | 0 |
D.12 | 0001100 | 01001100 | -2 | 10110011 | 2 |
D.13 | 0001101 | 10001101 | 0 | #N/A | 0 |
D.14 | 0001110 | 10001110 | 0 | #N/A | 0 |
D.15 | 0001111 | 11000111 | 2 | 00111000 | -2 |
D.16 | 0010000 | 00010011 | -2 | 11101100 | 2 |
D.17 | 0010001 | 10010001 | -2 | 01101110 | 2 |
D.18 | 0010010 | 10010010 | -2 | 01101101 | 2 |
D.19 | 0010011 | 10010011 | 0 | #N/A | 0 |
D.20 | 0010100 | 10010100 | -2 | 01101011 | 2 |
D.21 | 0010101 | 10010101 | 0 | #N/A | 0 |
D.22 | 0010110 | 10010110 | 0 | #N/A | 0 |
D.23 | 0010111 | 00010111 | 0 | #N/A | 0 |
D.24 | 0011000 | 10011000 | -2 | 01100111 | 2 |
D.25 | 0011001 | 10011001 | 0 | #N/A | 0 |
D.26 | 0011010 | 10011010 | 0 | #N/A | 0 |
D.27 | 0011011 | 00011011 | 0 | #N/A | 0 |
D.28 | 0011100 | 10011100 | 0 | #N/A | 0 |
D.29 | 0011101 | 00011101 | 0 | #N/A | 0 |
D.30 | 0011110 | 00011110 | 0 | #N/A | 0 |
D.31 | 0011111 | 00011100 | -2 | 11100011 | 2 |
D.32 | 0100000 | 00100101 | -2 | 11011010 | 2 |
D.33 | 0100001 | 10100001 | -2 | 01011110 | 2 |
D.34 | 0100010 | 00100110 | -2 | 11011001 | 2 |
D.35 | 0100011 | 10100011 | 0 | #N/A | 0 |
D.36 | 0100100 | 10100100 | -2 | 01011011 | 2 |
D.37 | 0100101 | 10100101 | 0 | #N/A | 0 |
D.38 | 0100110 | 10100110 | 0 | #N/A | 0 |
D.39 | 0100111 | 00100111 | 0 | #N/A | 0 |
D.40 | 0101000 | 00101001 | -2 | 11010110 | 2 |
D.41 | 0101001 | 10101001 | 0 | #N/A | 0 |
D.42 | 0101010 | 10101010 | 0 | #N/A | 0 |
D.43 | 0101011 | 00101011 | 0 | #N/A | 0 |
D.44 | 0101100 | 10101100 | 0 | #N/A | 0 |
D.45 | 0101101 | 00101101 | 0 | #N/A | 0 |
D.46 | 0101110 | 00101110 | 0 | #N/A | 0 |
D.47 | 0101111 | 00101010 | -2 | 11010101 | 2 |
D.48 | 0110000 | 00110010 | -2 | 11001101 | 2 |
D.49 | 0110001 | 10110001 | 0 | #N/A | 0 |
D.50 | 0110010 | 10110010 | 0 | #N/A | 0 |
D.51 | 0110011 | 00110011 | 0 | #N/A | 0 |
D.52 | 0110100 | 10110100 | 0 | #N/A | 0 |
D.53 | 0110101 | 00110101 | 0 | #N/A | 0 |
D.54 | 0110110 | 00110110 | 0 | #N/A | 0 |
D.55 | 0110111 | 00110111 | 2 | 11001000 | -2 |
K.55 | 0110111 | 10110111 | 4 | 01001000 | -4 |
D.56 | 0111000 | 10111000 | 0 | #N/A | 0 |
D.57 | 0111001 | 00111001 | 0 | #N/A | 0 |
K.57 | 0111001 | 10111001 | 2 | 01000110 | -2 |
D.58 | 0111010 | 00111010 | 0 | #N/A | 0 |
D.59 | 0111011 | 00111011 | 2 | 11000100 | -2 |
D.60 | 0111100 | 00111100 | 0 | #N/A | 0 |
D.61 | 0111101 | 10111101 | 4 | 01000010 | -4 |
D.62 | 0111110 | 00110100 | -2 | 11001011 | 2 |
D.63 | 0111111 | 10111011 | 4 | 01000100 | -4 |
D.64 | 1000000 | 01010100 | -2 | 10101011 | 2 |
D.65 | 1000001 | 11000001 | -2 | 00111110 | 2 |
D.66 | 1000010 | 11000010 | -2 | 00111101 | 2 |
D.67 | 1000011 | 11000011 | 0 | #N/A | 0 |
D.68 | 1000100 | 01000001 | -4 | 10111110 | 4 |
D.69 | 1000101 | 11000101 | 0 | #N/A | 0 |
D.70 | 1000110 | 11000110 | 0 | #N/A | 0 |
D.71 | 1000111 | 01000111 | 0 | #N/A | 0 |
D.72 | 1001000 | 01001001 | -2 | 10110110 | 2 |
D.73 | 1001001 | 11001001 | 0 | #N/A | 0 |
D.74 | 1001010 | 11001010 | 0 | #N/A | 0 |
D.75 | 1001011 | 01001011 | 0 | #N/A | 0 |
D.76 | 1001100 | 11001100 | 0 | #N/A | 0 |
D.77 | 1001101 | 01001101 | 0 | #N/A | 0 |
D.78 | 1001110 | 01001110 | 0 | #N/A | 0 |
D.79 | 1001111 | 01000101 | -2 | 10111010 | 2 |
D.80 | 1010000 | 01000011 | -2 | 10111100 | 2 |
D.81 | 1010001 | 11010001 | 0 | #N/A | 0 |
D.82 | 1010010 | 11010010 | 0 | #N/A | 0 |
D.83 | 1010011 | 01010011 | 0 | #N/A | 0 |
D.84 | 1010100 | 11010100 | 0 | #N/A | 0 |
D.85 | 1010101 | 01010101 | 0 | #N/A | 0 |
D.86 | 1010110 | 01010110 | 0 | #N/A | 0 |
D.87 | 1010111 | 01010111 | 2 | 10101000 | -2 |
D.88 | 1011000 | 11011000 | 0 | #N/A | 0 |
D.89 | 1011001 | 01011001 | 0 | #N/A | 0 |
D.90 | 1011010 | 01011010 | 0 | #N/A | 0 |
D.91 | 1011011 | 11010011 | 2 | 00101100 | -2 |
D.92 | 1011100 | 01011100 | 0 | #N/A | 0 |
D.93 | 1011101 | 01011101 | 2 | 10100010 | -2 |
D.94 | 1011110 | 11001110 | 2 | 00110001 | -2 |
D.95 | 1011111 | 11011110 | 4 | 00100001 | -4 |
D.96 | 1100000 | 01100010 | -2 | 10011101 | 2 |
D.97 | 1100001 | 11100001 | 0 | #N/A | 0 |
D.98 | 1100010 | 11100010 | 0 | #N/A | 0 |
D.99 | 1100011 | 01100011 | 0 | #N/A | 0 |
D.100 | 1100100 | 11100100 | 0 | #N/A | 0 |
D.101 | 1100101 | 01100101 | 0 | #N/A | 0 |
D.102 | 1100110 | 01100110 | 0 | #N/A | 0 |
D.103 | 1100111 | 11100111 | 4 | 00011000 | -4 |
D.104 | 1101000 | 11101000 | 0 | #N/A | 0 |
D.105 | 1101001 | 01101001 | 0 | #N/A | 0 |
D.106 | 1101010 | 01101010 | 0 | #N/A | 0 |
D.107 | 1101011 | 11101011 | 4 | 00010100 | -4 |
D.108 | 1101100 | 01101100 | 0 | #N/A | 0 |
D.109 | 1101101 | 11101001 | 2 | 00010110 | -2 |
D.110 | 1101110 | 11101010 | 2 | 00010101 | -2 |
D.111 | 1101111 | 11101101 | 4 | 00010010 | -4 |
D.112 | 1110000 | 00100100 | -4 | 11011011 | 4 |
D.113 | 1110001 | 01110001 | 0 | #N/A | 0 |
D.114 | 1110010 | 01110010 | 0 | #N/A | 0 |
D.115 | 1110011 | 01010001 | -2 | 10101110 | 2 |
D.116 | 1110100 | 01110100 | 0 | #N/A | 0 |
D.117 | 1110101 | 01110101 | 2 | 10001010 | -2 |
D.118 | 1110110 | 01010010 | -2 | 10101101 | 2 |
D.119 | 1110111 | 01110111 | 4 | 10001000 | -4 |
K.120 | 1111000 | 11111000 | 2 | 00000111 | -2 |
D.120 | 1111000 | 01111000 | 0 | #N/A | 0 |
D.121 | 1111001 | 01100001 | -2 | 10011110 | 2 |
D.122 | 1111010 | 01111011 | 4 | 10000100 | -4 |
D.123 | 1111011 | 01110011 | 2 | 10001100 | -2 |
D.124 | 1111100 | 01111100 | 2 | 10000011 | -2 |
D.125 | 1111101 | 01111101 | 4 | 10000010 | -4 |
D.126 | 1111110 | 01111110 | 4 | 10000001 | -4 |
D.127 | 1111111 | 11101110 | 4 | 00010001 | -4 |
5B/6B Code Table
Name | In 5b | Out 6b | Out Disparity | Alt 6b | Alt Disparity |
D.x.0 | 00000 | 000110 | -2 | 111001 | 2 |
D.x.1 | 00001 | 010001 | -2 | 101110 | 2 |
D.x.2 | 00010 | 010010 | -2 | 101101 | 2 |
D.x.3 | 00011 | 100011 | 0 | NA | NA |
D.x.4 | 00100 | 010100 | -2 | 101011 | 2 |
D.x.5 | 00101 | 100101 | 0 | NA | NA |
D.x.6 | 00110 | 100110 | 0 | NA | NA |
D.x.7 | 00111 | 000111 | 0 | NA | NA |
D.x.8 | 01000 | 011000 | -2 | 100111 | 2 |
D.x.9 | 01001 | 101001 | 0 | NA | NA |
D.x.10 | 01010 | 101010 | 0 | NA | NA |
D.x.11 | 01011 | 001011 | 0 | NA | NA |
D.x.12 | 01100 | 101100 | 0 | NA | NA |
D.x.13 | 01101 | 001101 | 0 | NA | NA |
D.x.14 | 01110 | 001110 | 0 | NA | NA |
D.x.15 | 01111 | 000101 | -2 | 111010 | 2 |
K.x.28 | 11100 | 111100 | 2 | 000011 | -2 |
D.x.16 | 10000 | 110110 | 2 | 001001 | -2 |
D.x.17 | 10001 | 110001 | 0 | NA | NA |
D.x.18 | 10010 | 110010 | 0 | NA | NA |
D.x.19 | 10011 | 010011 | 0 | NA | NA |
D.x.20 | 10100 | 110100 | 0 | NA | NA |
D.x.21 | 10101 | 010101 | 0 | NA | NA |
D.x.22 | 10110 | 010110 | 0 | NA | NA |
D.x.23 | 10111 | 010111 | 2 | 101000 | -2 |
D.x.24 | 11000 | 001100 | -2 | 110011 | 2 |
D.x.25 | 11001 | 011001 | 0 | NA | NA |
D.x.26 | 11010 | 011010 | 0 | NA | NA |
D.x.27 | 11011 | 011011 | 2 | 100100 | -2 |
D.x.28 | 11100 | 011100 | 0 | NA | NA |
D.x.29 | 11101 | 011101 | 2 | 100010 | -2 |
D.x.30 | 11110 | 011110 | 2 | 100001 | -2 |
D.x.31 | 11111 | 110101 | 2 | 001010 | -2 |
Overview
Content Tools