NEC Network Controller uPD98502 - Manual (Page 301)

CHAPTER 5 ETHERNET CONTROLLER
Preliminary User’s Manual S15543EJ1V0UM 301
5.3.3 Buffer descriptor format
The Transmit Descriptor format is shown in Figure 5-5 and the description is shown in Table 5-6.
Figure 5-5. Transmit Descriptor Format
31 16 15 0
Word 0 Attribute Size
Word 1 Buffer Address Pointer
Table 5-6. Attribute for Transmit Descriptor
Attribute & Size Bit Name Status
31 L Last Descriptor
30 D/L Data Buffer / Link Pointer
29 OWN Owner 1:Ethernet Controller 0: V R 4120A
Ethernet Controller sets this bit after it began to transfer
data into each descriptor.
28 DBRE Data Buffer Read Error
27 TUDR Transmit Underrun Error
26 CSE Carrier Sense Lost Error
25 LCOL Late Collision
24 ECOL Excessive Collision
23 EDFR Excessive Deferral
22:19 - Reserved for future use. Write 0s.
18 TGNT Transmit Giant Frame
17 - Reserved for future use. Write 0s.
16 TOK Transmit OK
15:0 SIZE Transmit Byte Count
The Receive Descriptor format is shown in Figure 5-6 and the description is shown in Table 5-7.
Figure 5-6. Receive Descriptor Format
31 16 15 0
Word 0 Attribute Size
Word 1 Buffer Address Pointer