
W89C840AF
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25
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Publication Release Date:October 2000
Revision 1.01
The Fast_Ethernet_Select in C18/CNCR register is used to select the mode in which the W89C840AF
is working in 10M or 100Mbps. In 100Mbps (100BASE) mode, the MAC will not check the SQE status when
transmitting a packet. In 10Mbps(10BASE) mode, the SQE signal will be checked by MAC. No further
function is controlled by the Fast_Ethernet_Select of C18/CNCR register.
Device identifying function
This function is to utilize the device configuration data stored in the device configuration registers, in
which some of them loaded from the external EEPROM. You can tell the vendor, device type, revision,
signature and your own defined code through reading the contents of these registers.
The F00/FID is a read-only register which contains the vendor ID. and device ID., used for
identification. Its
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contents is loaded from the external EEPROM when hardware reset only.
The second read only register F08/FREV used for identification. It contains the revision ID. which is
also loaded from EEPROM only. The Ethernet device identification code is also included in F08/FREV, but it
is a built in code, not loaded form EEPROM.
Another identification register is the F40/FSR, a read only, too. The signature code for Winbond
W89C840AF is built in the F40/FSR signature register. The 12Hth and 9aHth bytes will be read out
recursively when a number of consecutive PCI configuration space read operation is accessed to the F40/FSR.
The first, third, fifth,...etc. odd read operation will get 12H, however, the second, fourth, sixth,...etc. even read
operation will get 9aH.
For some special requirement, the field of driver area of F40/FSR can be used as a word-width data
buffer for latching the user defined identification code.
EEPROM hardware reset auto load and software programming function
The following configuration parameters should be stored in a EEPROM device for configuring the
W89C840AF and can be loaded into the corresponding configuration register while power-on reset occurring.
1) 6 bytes Ethernet ID.
2) 2 bytes subsystem ID.
3) 2 bytes subsystem vendor ID.
4) 2 bytes device ID.
5) 2 bytes vendor ID.
6) 1 bytes revision ID.
7) 1 byte booting device size
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power Management capability support and remote wake-up from LAN
8) 1 byte maximum latency
9) 1 byte minimum grant