SMC Networks SMC91C95 Product Manual page 31

RECEIVE FRAME STATUS WORD
This word is written at the beginning of each receive frame in memory. It is not available as a register.
HIGH ALGN BROD
BYTE ERR CAST
LOW
BYTE
ALGNERR - Frame had alignment error.
BRODCAST - Receive frame was broadcast.
BADCRC - Frame had CRC error.
ODDFRM - This bit when set indicates that the
received frame had an odd number of bytes.
TOOLNG - The received frame is longer than
802.3 maximum size (1518 bytes on the cable).
TOOSHORT - The received frame is shorter than
802.3 minimum size (64 bytes on the cable).
ADDRESS
ED 00 00 00 00 00
0D 00 00 00 00 00
01 00 00 00 00 00
2F 00 00 00 00 00
MULTCAST - Receive frame was multicast. If
hash value corresponds to a multicast table bit that
is set, and the address was a multicast, the
BAD ODD
CRC FRM
HASH VALUE
5 4 3
HASH VALUE 5-0
000 000
010 000
100 111
111 111
31
TOO
TOOLN
SHORT
G
2 1
HASH VALUE - Provides the hash value used to
index the Multicast Registers. Can be used by
receive routines to speed up the group address
search. The hash value consists of the six most
significant bits of the CRC calculated on the
Destination Address, and maps into the 64 bit
multicast table. Bits 5,4,3 of the hash value select
a byte of the multicast table, while bits 2,1,0
determine the bit within the byte selected.
Examples of the address mapping:
MULTICAST TABLE BIT
MT-0 bit 0
MT-2 bit 0
MT-4 bit 7
MT-7 bit 7
packet will pass address filtering regardless of
other filtering criteria.
MULT
CAST
0