Am79C971
141
P R E L I M I N A R Y
CSR62: Previous Transmit Byte Count
Bit
Name
Description
31-16 RES
Reserved locations. Written as
zeros and read as undefined.
15-12 RES
Reserved locations.
11-0
PXBC
Previous Transmit Byte Count.
This field is a copy of the BCNT
field of TMD1 of the previous
transmit descriptor.
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.
CSR63: Previous Transmit Status
Bit
Name
Description
31-16 RES
Reserved locations. Written as
zeros and read as undefined.
15-0
PXST
Previous Transmit Status. This
field is a copy of bits 31-16 of
TMD1 of the previous transmit
descriptor.
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.
CSR64: Next Transmit Buffer Address Lower
Bit
Name
Description
31-16 RES
Reserved locations. Written as
zeros and read as undefined.
15-0
NXBAL
Contains the lower 16 bits of the
next transmit buffer address from
which the Am79C971 controller
will transmit an outgoing frame.
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.
CSR65: Next Transmit Buffer Address Upper
Bit
Name
Description
31-16 RES
Reserved locations. Written as
zeros and read as undefined.
15-0
NXBAU
Contains the upper 16 bits of the
next transmit buffer address from
which the Am79C971 controller
will transmit an outgoing frame.
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.
CSR66: Next Transmit Byte Count
Bit
Name
Description
31-16 RES
Reserved locations. Written as
zeros and read as undefined.
15-12 RES
Reserved locations. Read and
written as zeros.
11-0
NXBC
Next Transmit Byte Count. This
field is a copy of the BCNT field of
TMD1 of the next transmit de-
scriptor.
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.
CSR67: Next Transmit Status
Bit
Name
Description
31-16 RES
Reserved locations. Written as
zeros and read as undefined.
15-0
NXST
Next Transmit Status. This field is
a copy of bits 31-16 of TMD1 of
the next transmit descriptor.
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.
7-0
RES
Reserved locations. Read and
written as zeros. Accessible only
when either the STOP or the
SPND bit is set.