AM79C976 Advanced Micro Devices, AM79C976 Datasheet - Page 191
![no-image](/images/manufacturer_photos/0/0/14/advanced_micro_devices_sml.jpg)
AM79C976
Manufacturer Part Number
AM79C976
Description
PCnet-PRO 10/100 Mbps PCI Ethernet Controller
Manufacturer
Advanced Micro Devices
Datasheet
1.AM79C976.pdf
(309 pages)
- Current page: 191 of 309
- Download datasheet (3Mb)
Bit
31-0
Bit
31-16
15-0
Bit
31-0
Bit
31-16
15-0
8/01/00
Name
RES
Name
RES
RCVRL
Name
RES
Name
RES
XMTRL
zeros and read as undefined.
zeros and read as undefined.
the two’s complement of the re-
ceive descriptor ring length. This
register is initialized during the
optional Am79C976 controller ini-
tialization routine based on the
value in the RLEN field of the ini-
tialization block. However, this
register can be manually altered.
The actual receive ring length is
defined by the current value in
this register. The ring length can
be defined as any value from
1 to 65535.
Read/Write accessible. These
bits are unaffected by H_RESET,
S_RESET, or STOP.
zeros and read as undefined.
zeros and read as undefined.
the two’s complement of the
transmit descriptor ring length.
This register is initialized during
the optional Am79C976 control-
ler initialization routine based on
the value in the TLEN field of the
initialization block. However, this
register can be manually altered.
The actual transmit ring length is
defined by the current value in
this register. The ring length can
be defined as any value from 1 to
65535.
Reserved locations. Written as
Reserved locations. Written as
Receive Ring Length. Contains
Reserved locations. Written as
Reserved locations. Written as
Transmit Ring Length. Contains
Description
Description
Description
Description
P R E L I M I N A R Y
Am79C976
Bit
31-0
Bit
31-16 RES
15-14 RES
13-12 RCVFW[1:0]Receive
Name
RES
Name
Read/Write accessible. These
bits are unaffected by H_RESET,
S_RESET, or STOP.
zeros and read as undefined.
zeros and read as undefined.
zeros and read as undefined.
RCVFW controls the point at
which receive DMA is requested
in relation to the number of re-
ceived bytes in the Receive
FIFO. RCVFW specifies the num-
ber of bytes which must be
present (once the frame has
been verified as a non-runt) be-
fore receive DMA is requested.
Note however that, if the network
interface is operating in half-du-
plex mode, in order for receive
DMA to be performed for a new
frame, at least 64 bytes must
have been received. This effec-
tively avoids having to react to re-
ceive frames which are runts or
suffer a collision during the slot
time (512 bit times). If the Runt
Packet Accept feature is enabled
or if the network interface is oper-
ating in full-duplex mode, receive
DMA will be requested as soon
as either the RCVFW threshold is
reached, or a complete valid re-
ceive frame is detected (regard-
less of length). When the Full
Duplex Runt Packet Accept Dis-
able (FDRPAD) bit (BCR9, bit 2)
is set and the Am79C976 control-
ler is in full-duplex mode, in order
for receive DMA to be performed
for a new frame, at least 64 bytes
must have been received. This
effectively disables the runt pack-
et accept feature in full duplex.
Description
Reserved locations. Written as
Description
Reserved locations. Written as
Reserved locations. Written as
FIFO
Watermark.
191
Related parts for AM79C976
Image
Part Number
Description
Manufacturer
Datasheet
Request
R
![AM27S29DC](/images/manufacturer_photos/0/0/14/advanced_micro_devices_tmb.jpg)
Part Number:
Description:
Advanced Micro Devices [4,096-Bit (512x8) Bipolar PROM]
Manufacturer:
Advanced Micro Devices
Datasheet:
![AM27S29APC](/images/manufacturer_photos/0/0/14/advanced_micro_devices_tmb.jpg)
Part Number:
Description:
Advanced Micro Devices [4,096-Bit (512x8) Bipolar PROM]
Manufacturer:
Advanced Micro Devices
Datasheet:
![AM29BL802CB-70RZE](/images/manufacturer_photos/0/0/14/advanced_micro_devices_tmb.jpg)
Part Number:
Description:
Advanced Micro Devices [8 Megabit (512 K x 16-Bit) CMOS 3.0 Volt-only Burst Mode Flash Memory]
Manufacturer:
Advanced Micro Devices
Datasheet:
![M41000001Y](/images/manufacturer_photos/0/0/14/advanced_micro_devices_tmb.jpg)
Part Number:
Description:
M41000001YAdvanced Micro Devices [32 Megabit (4 M x 8-Bit/2 M x 16-Bit) CMOS 3.0 Volt-only, Simultaneous Operation Flash Memory and 4 Mbit (512 K x 8-Bit/256 K x 16-Bit) Static RAM]
Manufacturer:
Advanced Micro Devices
Datasheet:
![AM95C94JC](/images/manufacturer_photos/0/0/14/advanced_micro_devices_tmb.jpg)
Part Number:
Description:
Advanced Burst Error Processor
Manufacturer:
Advanced Micro Devices
![AM7992BPC](/images/manufacturer_photos/0/0/14/advanced_micro_devices_tmb.jpg)
Part Number:
Description:
Serial interface adapter (SIA)
Manufacturer:
Advanced Micro Devices
Datasheet:
![AM9519ADC](/images/manufacturer_photos/0/0/14/advanced_micro_devices_tmb.jpg)
Part Number:
Description:
Universal interrupt controller
Manufacturer:
Advanced Micro Devices
Datasheet:
![AM27C256-150DC](/images/manufacturer_photos/0/0/14/advanced_micro_devices_tmb.jpg)
Part Number:
Description:
256 kilobit CMOS EPROM
Manufacturer:
Advanced Micro Devices
Datasheet:
![AM9128-10PC](/images/manufacturer_photos/0/0/14/advanced_micro_devices_tmb.jpg)
Part Number:
Description:
2048 x 8 static RAM, 100ns
Manufacturer:
Advanced Micro Devices
Datasheet:
![P8284A](/images/manufacturer_photos/0/0/14/advanced_micro_devices_tmb.jpg)
Part Number:
Description:
Manufacturer:
Advanced Micro Devices
Datasheet:
![DM81LS98N](/images/manufacturer_photos/0/0/14/advanced_micro_devices_tmb.jpg)
Part Number:
Description:
Three-State Octal Buffers
Manufacturer:
Advanced Micro Devices
Datasheet:
![AM2966PC](/images/manufacturer_photos/0/0/14/advanced_micro_devices_tmb.jpg)
Part Number:
Description:
AM2966PCOctal Dynamic Memory Drivers with Three-State Outputs
Manufacturer:
Advanced Micro Devices
Datasheet:
![DM81LS97N](/images/manufacturer_photos/0/0/14/advanced_micro_devices_tmb.jpg)
Part Number:
Description:
Three-State Octal Buffers
Manufacturer:
Advanced Micro Devices
Datasheet:
![DM81LS96N](/images/manufacturer_photos/0/0/14/advanced_micro_devices_tmb.jpg)
Part Number:
Description:
Three-State Octal Buffers
Manufacturer:
Advanced Micro Devices
Datasheet:
![PAL16L8-7PC](/images/manufacturer_photos/0/0/14/advanced_micro_devices_tmb.jpg)
Part Number:
Description:
TTL programmable array logic, 7ns
Manufacturer:
Advanced Micro Devices
Datasheet: