AM79C978A AMD [Advanced Micro Devices], AM79C978A Datasheet - Page 143

• Manufacturer Part Number: AM79C978A
• Description: Single-Chip 1/10 Mbps PCI Home Networking Controller
• Manufacturer: AMD [Advanced Micro Devices]

Bus Configuration Registers (BCRs)
The BCRs are used to program the configuration of
the bus interface and other special features of the
Am79C978A controller that are not related to the
IEEE 802.3 MAC functions. The BCRs are accessed
by first setting the appropriate RAP value and then by
performing a slave access to the BDP. See Table 36.
All BCR registers are 16 bits in width in Word I/O mode
(DWIO = 0, BCR18, bit 7) and 32 bits in width in DWord
I/O mode (DWIO = 1). The upper 16 bits of all BCR reg-
isters is undefined when in DWord I/O mode. These
bits should be written as zeros and should be treated
as undefined when read. The default value given for
any BCR is the value in the register after H_RESET.
Some of these values may be changed shortly after
H_RESET when the contents of the external EEPROM
is automatically read in. None of the BCR register val-
ues are affected by the assertion of the STOP bit or
S_RESET.
Note that several registers have no default value.
BCR0, BCR1, BCR3, BCR8, BCR10-17, and BCR21
are reserved and have undefined values. BCR2 and
BCR34 are not observable without first being pro-
grammed through the EEPROM read operation or a
user register write operation.
BCR0, BCR1, BCR16, BCR17, and BCR21 are regis-
ters that are used by other devices in the PCnet fam-
ily. Writing to these registers have no effect on the
operation of the Am79C978A controller.
Writes to those registers marked as “Reserved” will
have no effect. Reads from these locations will produce
undefined values.
Am79C978A
BCR0: Master Mode Read Active
Bit
31-16 RES
15-0
BCR1: Master Mode Write Active
Bit
31-16 RES
15-0
MSRDA
MSWRA
Name
Name
Reserved locations. Written as
Reserved
Reserved locations. Written as
Reserved
zeros and read as undefined.
H_RESET, the value in this regis-
ter will be 0005h. The setting of
this register has no effect on any
Am79C978A controller function.
It is only included for software
compatibility with other PCnet
family devices.
Read always. MSRDA is read only.
Write operations have no effect.
zeros and read as undefined.
H_RESET, the value in this regis-
ter will be 0005h. The setting of
this register has no effect on any
Am79C978A controller function.
It is only included for software
compatibility with other PCnet
family devices.
Read always. MSWRA is read only.
Write operations have no effect.
Description
Description
locations.
locations.
After
After
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