Is There Any Problem If The Value Of The Vacant Field (Word1, Word2 Bits 31 To 16); Of The Transmit Buffer Descriptor Is Not 0? Are The Values On The System Memory Rewritten; What Does The Packet Queue Pointer Field For Transmission Indication Indicate - NEC mPD98409 Q&A

Q.7.9
Is there any problem if the value of the vacant field (Word1, Word2 bits 31 to 16) of the transmit buffer
descriptor is not 0? Are the values on the system memory rewritten?
A.7.9
The vacant field (Word1, Word2 bits 31 to 16) may be a value other than 0. After reading two words of buffer
descriptors, the µ PD98409 internally ignores the information in the vacant field. The values on the system
memory are not rewritten.
LAST
31 30
31
Reference: µ PD98409 User's Manual 5.4.2 Structure of transmit data
Q.7.10

What does the Packet queue pointer field for transmission indication indicate?

A.7.10
The Packet queue pointer field indicates the address of the packet descriptor of the packet next to the one that
has just finished being transmitted. Note that it does not indicate the packet descriptor address of the packet that
has just finished being transmitted. Only the lower 15 bits of its address are reported.
Reference: µ PD98409 User's Manual 5.6 Transmit/Receive Indication
26
CHAPTER 7 TRANSMISSION
0
16
ADDRESS
Information S14769EJ1V0IF00
SIZE
15 0
0