AM79C973BKC AMD (ADVANCED MICRO DEVICES), AM79C973BKC Datasheet - Page 180

• Manufacturer Part Number: AM79C973BKC
• Manufacturer: AMD (ADVANCED MICRO DEVICES)

Specifications of AM79C973BKC

• Lead Free Status / Rohs Status: Not Compliant

7-0
BCR23: PCI Subsystem Vendor ID Register
Note: Bits 15-0 in this register are programmable
through the EEPROM.
Bit
31-0
180
MIN_GNT
RES
Name
Minimum Grant. Specifies the
minimum length of a burst period
the Am79C973/Am79C975 con-
troller needs to keep up with the
network activity. The length of the
burst period is calculated assum-
ing a clock rate of 33 MHz. The
register value specifies the time
in units of 1/4 ms. MIN_GNT is
aliased to the PCI configuration
space register MIN_GNT (offset
3Eh). The host will use the value
in the register to determine the
setting
Am79C975 Latency Timer regis-
ter.
Reserved locations. Written as
zeros and read as undefined.
Read accessible always; write
accessible only when either the
STOP or the SPND bit is set.
MAX_LAT is set to the value of
FFh by H_RESET which results
in a default maximum latency of
63.75 microseconds. It is recom-
mended to program the value of
18H via EEPROM. MAX_LAT is
not affected by S_RESET or
STOP.
Read accessible always; write
accessible only when either the
STOP or the SPND bit is set.
MIN_GNT is set to the value of
06h by H_RESET which results
in a default minimum grant of
1.5 ms, which is the time it takes
to Am79C973/Am79C975 con-
troller to read/write half of the
FIFO. (16 DWord transfers in
burst mode with one extra wait
state per data phase inserted by
the target.) Note that the default
is only a typical value. It also does
not take into account any descrip-
tor accesses. It is recommended
to program the value of 18H via
EEPROM. MIN_GNT is not af-
fected by S_RESET or STOP.
Description
of
the
Am79C973/
P R E L I M I N A R Y
Am79C973/Am79C975
15-0
BCR24: PCI Subsystem ID Register
Note: Bits 15-0 in this register are programmable
through the EEPROM.
Bit
31-16 RES
15-0
BCR25: SRAM Size Register
Bit
Note: Bits 7-0 in this register are programmable
through the EEPROM.
SVID
SID
Name
Name
Subsystem ID. SID is used to-
Subsystem Vendor ID. SVID is
used together with SID (BCR24,
bits 15-0) to uniquely identify the
add-in board or subsystem the
Am79C973/Am79C975 controller
is used in. Subsystem Vendor IDs
can be obtained form the PCI
SIG. A value of 0 (the default) in-
dicates
Am79C975 controller does not
support subsystem identification.
SVID is aliased to the PCI config-
uration space register Subsystem
Vendor ID (offset 2Ch).
Read accessible always. SVID is
read only. Write operations are
ignored. SVID is cleared to 0 by
H_RESET and is not affected by
S_RESET or by setting the STOP
bit.
Reserved locations. Written as
zeros and read as undefined.
gether with SVID (BCR23, bits
15-0) to uniquely identify the add-
in
Am79C973/Am79C975 controller
is used in. The value of SID is up
to the system vendor. A value of
0 (the default) indicates that the
Am79C973/Am79C975 controller
does not support subsystem
identification. SID is aliased to the
PCI configuration space register
Subsystem ID (offset 2Eh).
Read accessible always. SID is
read only. Write operations are
ignored. SID is cleared to 0 by
H_RESET and is not affected by
S_RESET or by setting the STOP
bit.
Description
Description
board
that
or
the
subsystem
Am79C973/
the