82595TX Datasheet, PDF (25/59 Pages) Intel Corporation – ISA/PCMCIA HIGH INTEGRATION ETHERNET CONTROLLER

82595TX
7 0 FRAME TRANSMISSION
The 82595TX performs all of the necessary func-
tions needed to transmit frames from its local mem-
ory If Transmit Concurrent Processing is enabled
the CPU must only program the Base and Host Ad-
dress Register with the starting address to be trans-
mitted copy a portion of the frame into the
82595TX’s transmit buffer located in local memory
(the number of bytes for this first portion is deter-
mined by the software driver without causing an Un-
derrun) issue a XMT command to the 82595TX and
complete the data copies for this frame to local
memory If Transmit Concurrent Processing is dis-
abled the CPU must copy an entire frame into the
82595TX’s transmit buffer located in local memory
set up the 82595TX’s Current Address Registers to
point to that frame and issue a XMT command to
the 82559TX The 82595TX performs all the link
management functions DMA operations and statis-
tics keeping to handle transmission onto the link and
communicate the status of the transmission to the
CPU The 82595TX performs automatic retransmis-
sion on collision with no CPU interaction
7 1 82595TX XMT Block Memory
Format
The format in which a XMT block is written to memo-
ry by the CPU is shown in Figure 7-1 for a 16-bit
interface Figure 7-2 shows this structure for an 8-bit
interface
Figure 7-1 XMT Block Memory Structure (16-Bit)
281630 – 4
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