AM79C976 Advanced Micro Devices, AM79C976 Datasheet - Page 214

• Manufacturer Part Number: AM79C976
• Description: PCnet-PRO 10/100 Mbps PCI Ethernet Controller
• Manufacturer: Advanced Micro Devices

Note: Bits 15-0 in this register are programmable
through the EEPROM.
Bit
31-16
15-8
7-0
214
Name
RES
MAX_LAT
MIN_GNT
SWSTYLE
All Other
[7:0]
00h
01h
02h
03h
04h
05h
zeros and read as undefined.
maximum arbitration latency the
Am79C976 controller can sustain
without causing problems to the
network activity. The register val-
ue specifies the time in units of
1/4 microseconds. MAX_LAT is
aliased to the PCI configuration
space register MAX_LAT (offset
3Fh). The host will use the value
in the register to determine the
setting of the Am79C976 Latency
Timer register.
Read/Write
MAX_LAT is set to the value of
18h by H_RESET which results
in a default maximum latency of 6
microseconds. MAX_LAT is not
affected by S_RESET or STOP.
imum length of a burst period the
Am79C976 controller needs to
keep up with the network activity.
The length of the burst period is
calculated assuming a clock rate of
Reserved locations. Written as
Maximum Latency. Specifies the
Minimum Grant. Specifies the min-
Description
64-bit address
PCnet-PCI
PCnet-PCI
PCnet-ISA
Reserved
controller
controller
controller
LANCE/
Name
VLAN
Style
RES
P R E L I M I N A R Y
Table 92. Software Styles
accessible.
Undefined
Am79C976
SSIZE32
0
1
1
1
1
1
Note: Bits 15-0 in this register are programmable
through the EEPROM.
Bit
31-16 RES
15-0
16-bit software
structures, non-burst or
burst access
RES
32-bit software
structures, non-burst or
burst access
32-bit software
structures, non-burst or
burst access
Not used
Not used
Undefined
Name
SVID
Initialization Block
Entries
Read/Write
MIN_GNT is set to the value of
18h by H_RESET which results
in a default minimum grant of 6
µs. MIN_GNT is not affected by
S_RESET or STOP.
33 MHz. The register value speci-
fies the time in units of 1/4 µs.
MIN_GNT is aliased to the PCI
configuration
MIN_GNT (offset 3Eh). The host
will use the value in the register to
determine the setting of the
Am79C976
register.
zeros and read as undefined.
used together with SID (BCR24,
bits 15-0) to uniquely identify the
add-in board or subsystem the
Am79C976 controller is used in.
Subsystem Vendor IDs can be ob-
tained from the PCI SIG. A value
of 0 (the default) indicates that the
Am79C976 controller does not
support subsystem identification.
Description
Reserved locations. Written as
Subsystem Vendor ID. SVID is
16-bit software structures,
non-burst access only
RES
32-bit software structures,
non-burst access only
32-bit software structures,
non-burst or burst access
32-bit software structures,
non-burst or burst access
32-bit software structures,
32-byte descriptors, non-
burst or burst access
Undefined
Descriptor Ring Entries
Latency
space
accessible.
8/01/00
register
Timer