AMD
P R E L I M I N A R Y
has also been set to a 1 and the PCMCIA pin is set to 1. The value
that is read from this bit represents the current value of theTXDATA
pin of the Am79C930 device.
A complete description of the control of the function of theTXDATA
pin is described in the Multi-Function Pin section.
TCR8: Start Delimiter LSB
This register is the Start Delimiter LSB register.
CONFIGURATION REGISTER INDEX:
08h
Bit
Name
Reset Value
Description
7–0
SDLT[7:0]
00h
Start of Frame Delimiter. This register contains the LSB of the 24-bit
start delimiter field that is used for start of frame recognition during
reception and transmission in order to determine the start of MAC
CRC calculation. (Note that PFL of TCR3 may also affect start of
MAC CRC calculation start.) All, none or part of the 24-bit Start De-
limiter may be used for start of frame recognition by appropriate set-
tings of the SD[1:0] bits in the Network Configuration Register
(TCR0). Start of Frame detection is performed on the bits in the or-
der that they appear on the medium, with the SDLT LSB, bit 0, being
checked against the first bit to arrive at the Am79C930 (RX case)
or the first bit to leave the Am79C930 (TX case) and continuing in
that order.
TCR9: Start Delimiter CSB
This register is the Start Delimiter CSB register.
CONFIGURATION REGISTER INDEX:
09h
Bit
Name
Reset Value
Description
7–0
SDLT[15:8]
00h
Start of Frame Delimiter. This register contains the Center Signifi-
cant Byte (CSB) of the 24-bit start delimiter field that is used for start
of frame recognition during reception and transmission in order to
determine the start of MAC CRC calculation. (Note that PFL of
TCR3 may also affect start of MAC CRC calculation start.) All, none
or part of the 24-bit Start Delimiter may be used for start of frame
recognition by appropriate settings of the SD[1:0] bits in the Net-
work Configuration Register (TCR0). Start of Frame detection is
performed on the bits in the order that they appear on the medium,
with the SDLT LSB, bit 0, being checked against the first bit to arrive
at the Am79C930 (RX case) or the first bit to leave the Am79C930
(TX case) and continuing in that order.
TCR10: Start Delimiter MSB
This register is the Start Delimiter MSB register.
CONFIGURATION REGISTER INDEX:
0Ah
Bit
Name
Reset Value
Description
7–0
SDLT[23:16]
00h
Start of Frame Delimiter. This register contains the MSB of the
24-bit start delimiter field that is used for start of frame recognition
during reception and transmission in order to determine the start of
MAC CRC calculation. (Note that PFL of TCR3 may also affect start
of MAC CRC calculation start.) All, none or part of the 24-bit Start
110
Am79C930
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