Intel GD82559ER - Manual (Page 35)

Datasheet 29
Networking Silicon — GD82559ER
All accesses, either read or write, are preceded by a command instruction to the device. The
address field is six bits for a 64 register EEPROM or eight bits for a 256 register EEPROM. The
end of the address field is indicated by a dummy zero bit from the EEPROM, which indicates the
entire address field has been transferred to the device. An EEPROM read instruction waveform is
shown in the figure below.
The 82559ER performs an automatic read of seven words (0H, 1H, 2H, AH, Bh, Ch and DH) of the
EEPROM after the de-assertion of Reset.
The 82559ER EEPROM format is shown below in Figure 12 .
Figure 11. 64 Word EEPROM Read Instruction Waveform
Word 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0H IA Byte 2 IA Byte 1
1H IA Byte 4 IA Byte 3
2H IA Byte 6 IA Byte 5
AH Sig ID 0b BD Rev ID 1b DPD 0b 00b 0b STB
Ena
0b
BH Subsystem ID
CH Subsystem Vendor ID
DH Reserved
Figure 12. 82559ER EEPROM Format
A
1
A
0
E E C S
E E S K
E E D I
E E D O
A
5
A
4
A
2
D
1 5
D
0
R E A D O P c o d e
A
3
A
1
A
0