AM79C976 Advanced Micro Devices, AM79C976 Datasheet - Page 215

• 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
15-0
Bit
Note: Bits 7-0 in this register are programmable
through the EEPROM.
31-16
15-0
8/01/00
Name
RES
SID
Name
RES
SRAM_SIZE SRAM Size. Specifies the total
SVID is aliased to the PCI config-
uration space register Subsystem
Vendor ID (offset 2Ch).
SVID is read only. Write opera-
tions are ignored. SVID is cleared
to 0 by H_RESET and is not af-
fected by S_RESET or by setting
the STOP bit.
zeros and read as undefined.
gether with SVID (BCR23, bits
15-0) to uniquely identify the add-
in
Am79C976 controller is used in.
The value of SID is up to the sys-
tem vendor. A value of 0 (the de-
fault)
Am79C976 controller does not
support subsystem identification.
SID is aliased to the PCI configu-
ration space register Subsystem
ID (offset 2Eh).
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.
zeros and read as undefined.
size of the SSRAM buffer in units
of 512-byte pages. For example,
assume that the external memory
consists of one 64K X 32 bit SS-
RAM, for a total of 256K bytes. In
this case SRAM_SIZE should be
set to 512 (256K divided by 512).
This field must be initialized to the
appropriate value, either by the
Reserved locations. Written as
Subsystem ID. SID is used to-
Reserved locations. Written as
Description
Description
board
indicates
or
subsystem
P R E L I M I N A R Y
that
the
the
Am79C976
Bit
Note: Bits 7-0 in this register are programmable
through the EEPROM.
31-16 RES
15-0
Name
SRAM_BND SRAM Boundary. Specifies the
EEPROM or by the host CPU.
SRAM_SIZE must be set to a val-
ue less than or equal to 2000h.
Values larger than 2000h will
cause incorrect behavior.
Note: The minimum allowed
number of pages is eight for nor-
mal
Am79C976 controller will not op-
erate correctly with less than the
eight pages of memory. When
the minimum number of pages is
used, these pages must be allo-
cated four each for transmit and
receive.
CAUTION:
SRAM_BND and SRAM_SIZE to
the same value will cause data
corruption.
Read/Write
SRAM_SIZE is set to 000000b
during H_RESET and is unaffect-
ed by S_RESET or STOP.
The transmit buffer in the SRAM
begins at address 0 and ends at
the address (SRAM_BND*512)-
1. Therefore, the receive buffer
always begins on a 512-byte
boundary.
SRAM_BND must be initialized to
an appropriate value, either by
the EEPROM or by the host CPU.
SRAM_BND must be set to a val-
ue less than or equal to IFFCh.
zeros and read as undefined.
size of the transmit buffer portion
of the SRAM in units of 512-byte
pages.
SRAM_BND is set to 10, then
5120 bytes of the SRAM will be
allocated for the transmit buffer
and the rest will be allocated for
the receive buffer.
Description
Reserved locations. Written as
network
For
operation.
example
Programming
accessible.
215
The
if