
RTL8100B(L) 
2001-11-9 
Rev.1.41 
32 
6. EEPROM (93C46) Contents 
The 93C46 is a 1K-bit EEPROM. Although it is actually addressed by words, its contents are listed below by bytes for 
convenience. The RTL8100B(L) performs a series of EEPROM read operations from the 93C46 addresses 00H to 31H. 
 
It is suggested to obtain Realtek approval before changing the default settings of the EEPROM. 
Bytes
00h 
01h 
Contents
29h 
81h 
Description 
These 2 bytes contain the ID code word for the RTL8100B(L). The RTL8100B(L) will load 
the contents of the EEPROM into the corresponding location if the ID word (8129h) is right, 
otherwise, the RTL8100B(L) will not proceed with the EEPROM autoload process. 
Reserved. The RTL8100B(L) no longer supports autoload of Vender ID and Device ID. 
The default values of VID and DID are hex 10EC and 8139, respectively. 
PCI Subsystem Vendor ID, PCI configuration space offset 2Ch-2Dh. 
PCI Subsystem ID, PCI configuration space offset 2Eh-2Fh. 
PCI Minimum Grant Timer, PCI configuration space offset 3Eh. 
PCI Maximum Latency Timer, PCI configuration space offset 3Fh. 
Bits 7-6 map to bits 7-6 of the Media Status register (MSR); Bits 5, 4, 0 map to bits 13, 
12, 8 of the Basic Mode Control register (BMCR); Bits 3-2 are reserved. If the network 
speed is set to Auto-Detect mode (i.e. Nway mode), then Bit 1=0 means the local 
RTL8100B(L) supports flow control (IEEE 802.3x). In this case, Bit 10=1 in the 
Auto-negotiation Advertisement Register (offset 66h-67h), and Bit 1=1 means the local 
RTL8100B(L) does not support flow control. In this case, Bit 10=0 in Auto-negotiation 
Advertisement. This is because there are Nway switch hubs which keep sending flow 
control pause packets for  no reason, if the link partner supports Nway flow control. 
RTL8100B(L) Configuration register 3, operational register offset 59H. 
After auto-load command or hardware reset, the RTL8100B(L) loads the Ethernet ID to 
IDR0-IDR5 of RTL8100B(L)'s I/O registers.  
RTL8100B(L) Configuration register 0, operational registers offset 51h. 
RTL8100B(L) Configuration register 1, operational registers offset 52h. 
Reserved. Do not change this field without Realtek approval. 
Power Management Capabilities. PCI configuration space address 52h and 53h.  
Reserved. Do not change this field without Realtek approval. 
Power Management Control/Status. PCI configuration space address 55h. 
Reserved. Do not change this field without Realtek approval. 
RTL8100B(L) Configuration register 4, operational registers offset 5Ah. 
PHY1_PARM_U Reserved. Do not change this field without Realtek approval. 
PHY Parameter 1-U for RTL8100B(L). Operational registers of the RTL8100B(L) are 
from 78h to 7Bh.  
PHY2_PARM_U Reserved. Do not change this field without Realtek approval. 
PHY Parameter 2-U for RTL8100B(L). Operational register of the RTL8100B(L) is 
80h.  
02h-05h 
- 
06h-07h 
08h-09h 
0Ah 
0Bh 
0Ch 
SVID 
SMID 
MNGNT 
MXLAT 
MSRBMCR 
0Dh 
0Eh-13h 
CONFIG3 
Ethernet ID 
14h 
15h 
CONFIG0 
CONFIG1 
PMC 
16h-17h 
18h 
PMCSR 
19h 
CONFIG4 
1Ah-1Dh 
1Eh