AM79C973KCW Advanced Micro Devices, AM79C973KCW Datasheet - Page 293

• Manufacturer Part Number: AM79C973KCW
• Description: PCnet-FAST III Single-Chip 10/100 Mbps PCI Ethernet Controller with Integrated PHY
• Manufacturer: Advanced Micro Devices

Descriptor
Descriptor
Descriptor
Descriptor
Descriptor
Descriptor
Descriptor
Descriptor
Descriptor
#1
#2
#3
#4
#5
#6
#7
#8
#9
OWN = 1
SIZE = HEADER_SIZE (minimum 64 bytes)
OWN = 1
SIZE = S1+S2+S3+S4
OWN = 0
SIZE = 1518 - (S1+S2+S3+S4+HEADER_SIZE)
OWN = 1
SIZE = HEADER_SIZE (minimum 64 bytes)
OWN = 1
SIZE = S1+S2+S3+S4
OWN = 0
SIZE = 1518 - (S1+S2+S3+S4+HEADER_SIZE)
OWN = 1
SIZE = HEADER_SIZE (minimum 64 bytes)
OWN = 1
SIZE = S1+S2+S3+S4
OWN = 0
SIZE = 1518 - (S1+S2+S3+S4+HEADER_SIZE)
Figure 91. LAPP 3 Buffer Grouping for Two-interrupt Method
P R E L I M I N A R Y
Am79C973/Am79C975
STP = 0
STP = 0
STP = 1
STP = 0
STP = 0
STP = 1
STP = 0
STP = 0
STP = 1
Note that the times needed for tasks S1,
S2, S3, S4, and S6 should be divided by
0.8 microseconds to yield an equivalent
number of network byte times before
subtracting these quantities from the
expected message size A.
A = Expected message size in bytes
S1 = Interrupt latency
S2 = Application call latency
S3 = Time needed for driver to write
S4 = Time needed for driver to copy
S6 = Time needed for driver to copy
to third descriptor
data from buffer #1 to
application buffer space
data from buffer #2 to
application buffer space
21510B-B4
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