Individual Address Mask; Non-Rwr Maximum Retry Limit - Motorola MC68824 User Manual

II
If the boolean value of the expression is true, then the frame is accepted. For a more detailed
explanation and examples of group addressing, see APPENDIX B FRAME FORMATS AND AD-
DRESSING. This parameter is initialized by the host through the initialization table and may be
altered or read via the SET/READ VALUE command thereafter. The middle and high words must
be zero if the address length is two bytes. Note that the group address mask is stored following
the IEEE format.
Offset
60
62
64
D
e
I
MSB
2.1.21 Individual Address Mask
B
A
Group Address Mask - low Word
Group Address Mask - Middle Word
Group Address Mask - High Word lSB
I
The individual address mask can be either two or six bytes and must have its least significant bit
set to zero. It is used to modify the test used by the TBC for individual node address recognition.
The mathematical expression for accepting frames using the individual address mechanism is:
Destination Address AND IA.MASK=This Station Address AND IA.MASK
If the boolean value of the expression is true, then the frame is accepted. For a more detailed
explanation and examples of individual addressing, see APPENDIX B FRAME FORMATS AND
ADDRESSING. This parameter is initialized by the host through the initialization table and may
be altered or read via the SET/READ VALUE command thereafter. The middle and high words
should be zero if the address length is 16 bits. Note that the individual address mask is stored
following the IEEE format.
Offset
66
68
6A
D
e
B A
Individual Address Mask - low Word
Individual Address Mask - Middle Word
Individual Address Mask - High Word
lSB
I
2.1.22 Non-RWR Maximum Retry Limit
The maximum number of non-request with response retries sets an upper bound to the number
of times the TBC will attempt to transmit the same message. This parameter is initialized by the
host through the initialization table and may be altered or read via the SET/READ VALUE command
thereafter. Trying to send a frame again (retrying) is necessary when long host bus latency
conditions occur, sometimes causing the frame transmission to be aborted. The TBC will keep
attempting to send a message until this retry limit is met. This maximum retry limit is user
programmable with the TBC supporting a maximum of 255 retries. If the frame still has not been
sent when the maximum retry limit is met, negative confirmation appears in the confirmation
word of the frame descriptor and the TBC will stop trying to send it. The maximum retry limit for
non-RWR messages is not an IEEE 802.4 parameter.
Offset
6e
MOTOROLA
?R
D
o
I
0
I
0
e
B A
o
I
0
I
0
I
0
I
0
I
Non-RWR Maximum Retry limit
MC68824 USER'S MANUAL