KS8999_11 MICREL [Micrel Semiconductor], KS8999_11 Datasheet - Page 49

• Manufacturer Part Number: KS8999_11
• Description: Integrated 9-Port 10/100 Switch with PHY and Frame Buffer
• Manufacturer: MICREL [Micrel Semiconductor]

January 2005
Micrel, Inc.
4B/5B Coding
In 100BaseTX and 100BaseFX the data and frame control are encoded in the transmitter (and decoded in the
receiver) using a 4B/5B code. The extra code space is required to encode extra control (frame delineation) points. It
is also used to reduce run length as well as supply sufficient transitions for clock recovery. The table below provides
the translation for the 4B/5B coding.
Code Type
Control
Invalid
Data
Not defined
Not defined
Not defined
Not defined
Not defined
Not defined
Not defined
Not defined
Not defined
Not defined
Not defined
Not defined
Not defined
Not defined
4B Code
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
0101
0101
Table 13. 4B/5B Coding
5B Code
49
11110
01001
10100
10101
01010
01011
01110
01111
10010
10011
10110
10111
11010
11011
11100
11101
11111
11000
10001
01101
00111
00100
00000
00001
00010
00011
00101
00110
01000
01100
10000
11001
Start delimiter part 1
Start delimiter part 2
End delimiter part 1
End delimiter part 2
Transmit error
Data value C
Data value D
Data value 0
Data value 1
Data value 2
Data value 3
Data value 4
Data value 5
Data value 6
Data value 7
Data value 8
Data value 9
Data value A
Data value B
Data value E
Data value F
Invalid code
Invalid code
Invalid code
Invalid code
Invalid code
Invalid code
Invalid code
Invalid code
Invalid code
Invalid code
Value
Idle
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