
105
STP2002QFP
Fast Ethernet, Parallel Port, SCSI (FEPS) - STP2002QFP
Sun Microsystems,
7.5.20 ERX Receive Descriptor PointerTable 124: ERX Configuration Register Definition
Field Bits Description Type
Rx_DMA_Enable 0 When set to 1’, the DMA operation of the
channel is enabled. The load control state
machine will start responding to RX_MAC
requests for data transfer. When cleared to
0, the DMA operation of the channel will
cease as soon as the transfer of the current
frame has ben completed.
R/W
2:1 Reserved R
First_Byte_Offset 5:3 This field determines the offset of the first
data byte of the packet within the first
double-word of packet data in the RxFIFO
and in the host data buffer.
R/W
8:6 Reserved R
Desc_Ring_Size 10:9 This field determines the number of
descriptor entries in the ring. These bits are
encoded as follows:
00: 32 entries
01: 64 entries
10: 128 entries
11: 256 entries
R/W
15:11 Reserved R
Checksum_Start_Offset 22:16 Indicates the number of half-words from
the first byte of the packet that should be
skipped before the TCP checksum calcula-
tion begins
R/W
Table 125: ERX Receive Descriptor Pointer Register Address
Register Physical Address Access Size
ERX receive descriptor pointer register 0x8C0_4004 4 bytes