AM79C978 Advanced Micro Devices, AM79C978 Datasheet - Page 203

• Manufacturer Part Number: AM79C978
• Description: Single-Chip 1/10 Mbps PCI Home Networking Controller
• Manufacturer: Advanced Micro Devices

15-12 ZEROS
11-0
CXDA+0Ch
CXDA+0Ch
CXDA+00h
CXDA+04h
CXDA+08h BUFF UFLO
CXDA+00h BUFF UFLO
CXDA+04h
CXDA+08h
Address
Address
CXDA+00h
CXDA+02h
CXDA+04h
CXDA+06h
Address
MCNT
OWN
OWN
31
31
BUFF
OWN
15
1
RFRTAG will be read as all zeros.
See the section on Receive
Frame Tagging for details.
This
Am79C978 controller will write
zeros to these locations.
Message Byte Count is the length
in bytes of the received message,
expressed as an unsigned binary
integer. MCNT is valid only when
ERR is clear and ENP is set.
MCNT
Am79C978
cleared by the host.
ERR
ERR
30
30
field
UFLO
ADD_
ADD_
ERR
FCS
DEF
DEF
FCS
14
EX
EX
29
29
1
is
Table 85. Transmit Descriptor (SWSTYLE = 0)
Table 86. Transmit Descriptor (SWSTYLE = 2)
Table 87. Transmit Descriptor (SWSTYLE = 3)
is
written
MORE/
MORE/
LTINT
LTINT
controller
LCOL
LCOL
ADD_
FCS
DEF
28
28
reserved.
EX
13
1
LCAR
LCAR
ONE
ONE
by
27
27
MORE/
LTINT
LCOL
12
1
The
and
the
Am79C978
RTRY
RTRY
DEF
DEF
26
26
LCAR
USER SPACE
USER SPACE
ONE
TBADR[31:0]
TBADR[31:0]
11
TBADR[15:0]
RMD3
Bit
31-0
Transmit Descriptors
When SWSTYLE (BCR20, bits 7-0) is set to 0, the soft-
ware structures are defined to be 16 bits wide, and
transmit descriptors look like Table 85 (CXDA = Current
Transmit Descriptor Address).
When SWSTYLE (BCR 20, bits 7-0) is set to 2, the
software structures are defined to be 32 bits wide, and
transmit descriptors look like Table 86 (CXDA = Current
Transmit Descriptor Address).
When SWSTYLE (BCR 20, bits 7-0) is set to 3, then the
software structures are defined to be 32 bits wide, and
transmit descriptors look like Table 87 (CXDA = Current
Transmit Descriptor Address).
RES
STP
STP
25
25
RTRY
DEF
US
Name
10
ENP
RES
ENP
24
24
BPE
RES
BPE
RES
23
23
STP
9
User Space. Reserved for user
defined space.
Description
BCNT
22-16
22-16
RES
RES
RES
ENP
8
15-12
15-12
1111
RES
1111
TDR
TBADR[23:16]
11-4
RES
11-4
RES
7-0
BCNT
BCNT
TRC
TRC
3-0
3-0
203