am79c864a Advanced Micro Devices, am79c864a Datasheet - Page 38

• Manufacturer Part Number: am79c864a
• Description: Physical Layer Controller With Scrambler Plc-s
• Manufacturer: Advanced Micro Devices

Encoder
The Encoder performs the 4B/5B encoding of data sym-
bols to be transmitted over the physical medium. The
four bits of data and one control bit from the MAC are
encoded into a unique five bit symbol which is sent to the
PDT. Although the Encoder operates on symbol pairs,
each symbol is encoded independently of the other.
The symbol encoding is defined in Table 16.
3-40
Symbol
Q
AMD
H
K
R
S
H
H
V
V
V
H
V
H
A
B
C
D
E
J
T
0
1
2
3
4
5
6
7
8
9
F
I
Table 15. 4B/5B Decoding of Data
Encoded Input
0 0 0 0 0
1 1 1 1 1
0 0 1 0 0
1 1 0 0 0
1 0 0 0 1
0 1 1 0 1
0 0 1 1 1
1 1 0 0 1
0 0 0 0 1
0 0 0 1 0
0 0 0 1 1
0 0 1 0 1
0 0 1 1 0
0 1 0 0 0
0 1 1 0 0
1 0 0 0 0
1 1 1 1 0
0 1 0 0 1
1 0 1 0 0
1 0 1 0 1
0 1 0 1 0
0 1 0 1 1
0 1 1 1 0
0 1 1 1 1
1 0 0 1 0
1 0 0 1 1
1 0 1 1 0
1 0 1 1 1
1 1 0 1 0
1 1 0 1 1
1 1 1 0 0
1 1 1 0 1
The SUPERNET 2 Family for FDDI 1994 Data Book
Decoded Output
1 0 0 0 0
1 0 1 1 1
1 0 1 0 0
1 1 1 0 0
1 0 0 1 1
1 1 1 0 1
1 0 0 0 1
1 1 0 0 1
1 0 1 0 0
1 0 1 0 0
1 1 0 0 0
1 1 0 0 0
1 1 0 0 0
1 0 1 0 0
1 1 0 0 0
1 0 1 0 0
0 0 0 0 0
0 0 0 0 1
0 0 0 1 0
0 0 0 1 1
0 0 1 0 0
0 0 1 0 1
0 0 1 1 0
0 0 1 1 1
0 1 0 0 0
0 1 0 0 1
0 1 0 1 0
0 1 0 1 1
0 1 1 0 0
0 1 1 0 1
0 1 1 1 0
0 1 1 1 1
P R E L I M I N A R Y
STREAM CIPHER SCRAMBLER
Background
A popular implementation of FDDI is the replacement of
fiber with unshielded twisted pair wire (UTP). When a
digital signal is transmitted over copper wire it radiates
radio frequency (rf) energy. FDDI encoded data has re-
petitive patterns which result in peaks in the rf spectrum
Symbol
INV
INV
INV
INV
INV
INV
INV
INV
Q
H
R
C
D
K
T
S
A
B
E
F
J
0
1
2
3
4
5
6
7
8
9
I
Table 16. 4B/5B Encoding of Data
Data Input
1 0 0 0 0
1 0 1 1 1
1 0 1 0 0
1 1 1 0 0
1 0 0 1 1
1 1 1 0 1
1 0 0 0 1
1 1 0 0 1
1 1 1 1 0
1 0 1 0 1
1 0 1 1 0
1 1 1 1 1
1 1 0 0 0
1 1 0 1 0
1 1 0 1 1
0 0 0 0 0
0 0 0 0 1
0 0 0 1 0
0 0 0 1 1
0 0 1 0 0
0 0 1 0 1
0 0 1 1 0
0 0 1 1 1
0 1 0 0 0
0 1 0 0 1
0 1 0 1 0
0 1 0 1 1
0 1 1 0 0
0 1 1 0 1
0 1 1 1 0
0 1 1 1 1
1 0 0 10
Encoded Output
0 0 0 0 0
1 1 1 1 1
0 0 1 0 0
1 1 0 0 0
1 0 0 0 1
0 1 1 0 1
0 0 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 0 1 1 0
1 0 1 1 1
1 1 0 1 0
1 1 0 1 1
1 1 1 0 0
1 1 1 0 1
1 1 0 0 1
1 1 1 1 0
0 1 0 0 1
1 0 1 0 0
1 0 1 0 1
0 1 0 1 0
0 1 0 1 1
0 1 1 1 0
0 1 1 1 1
1 0 0 1 0
1 0 0 1 1