134
Am79C971
15-0
CXBAU
Contains the upper 16 bits of the
current transmit buffer address
from which the Am79C971 con-
troller is transmitting.
Read/Write accessible only when
either the STOP or the SPND bit
is set. These bits are unaffected
by H_RESET, S_RESET, or
STOP.
CSR22: Next Receive Buffer Address Lower
Bit
Name
Description
31-16 RES
Reserved locations. Written as
zeros and read as undefined.
15-0 NRBAL
Contains the lower 16 bits of the
next receive buffer address to
which the Am79C971 controller
will store incoming frame data.
Read/Write accessible only when
either the STOP or the SPND bit
is set. These bits are unaffected
by H_RESET, S_RESET, or
STOP.
CSR23: Next Receive Buffer Address Upper
Bit
Name
Description
31-16
RES
Reserved locations. Written as
zeros and read as undefined.
15-0
NRBAU
Contains the upper 16 bits of the
next receive buffer address to
which the Am79C971 controller
will store incoming frame data.
Read/Write accessible only when
either the STOP or the SPND bit
is set. These bits are unaffected
by H_RESET, S_RESET, or
STOP.
CSR24: Base Address of Receive Ring Lower
Bit
Name
Description
31-16
RES
Reserved locations. Written as
zeros and read as undefined.
15-0
BADRL
Contains the lower 16 bits of the
base address of the Receive
Ring.
Read/Write accessible only when
either the STOP or the SPND bit
is set. These bits are unaffected
by H_RESET, S_RESET, or
STOP.
CSR25: Base Address of Receive Ring Upper
Bit
Name
Description
31-16
RES
Reserved locations. Written as
zeros and read as undefined.
15-0
BADRU
Contains the upper 16 bits of the
base address of the Receive
Ring.
Read/Write accessible only when
either the STOP or the SPND bit
is set. These bits are unaffected
by H_RESET, S_RESET, or
STOP.
CSR26: Next Receive Descriptor Address Lower
Bit
Name
Description
31-16
RES
Reserved locations. Written as
zeros and read as undefined.
15-0
NRDAL
Contains the lower 16 bits of the
next receive descriptor address
pointer.
Read/Write accessible only when
either the STOP or the SPND bit
is set. These bits are unaffected
by H_RESET, S_RESET, or
STOP.
CSR27: Next Receive Descriptor Address Upper
Bit
Name
Description
31-16
RES
Reserved locations. Written as
zeros and read as undefined.
15-0
NRDAU
Contains the upper 16 bits of the
next receive descriptor address
pointer.
Read/Write accessible only when
either the STOP or the SPND bit
is set. These bits are unaffected
by H_RESET, S_RESET, or
STOP.
CSR28: Current Receive Descriptor Address Lower
Bit
Name
Description
31-16
RES
Reserved locations. Written as
zeros and read as undefined.