Motorola MC68824 User Manual page 87

II
PRIVATE AREA
RX EOO ACCESS CLASS 6
FREE Fa POOL POINTER
FREE SO POOL POINTER
Figure 4-7. Initalization of a Reception Queue
for the other access classes is the same. Each receive queue must consist of at least one dummy
FO (FD1). The dummy FO is used to start the linking procedure and contains the pointer to the
next FO when there is one as shown in Figure 4-8. Therefore, the host must not remove the last
FO, which serves as the dummy FD, from the queue. In Figure 4-8, the TBC has received one
frame and has stored it using F02 and two BOs (B02 and B03).
4.3.3 TBe's Actions Upon Reception
As the TBC accepts frames addressed to it, it takes frame descriptors and buffer descriptors from
the beginning of the free frame descriptor and free buffer descriptor pools.
MOTOROLA
4-14
PRIVATE AREA
RX EOO ACCESS CLASS 6
FREE Fa POOL POINTER
FREE SO POOL POINTER
Figure 4-8. Reception Queue After Receiving One Frame
MC68824 USER'S MANUAL