Table of Contents
Advertisement
HP 27130B
TRANSACTIONS
Each transfer between the MUX and the host computer is called a "transaction", and occurs over the
I/O channel. Each transaction represents a single read or write (data, status, etc.)
Each read or write is preceded by a Connect Logical Channel (CLC) request block from the host com-
puter. The CLC request is in response to an SRQ signal, request
I
ng the next order, from the MUX.
CONNECT LOGICAL CHANNEL (CLC) REQUEST FORMAT
The Connect Logical Channel (CLC) request block has the following format:
7
6
5
4
3
2
1
0
byte 0
high byte log channel
ID
~
.
1
low byte log channel
ID
•
I
•
•
•
I
•
· ·
· ·
·
•
•
2
S
BLK
F
res
request code
•
I
•
•
I
·
L
·
•
·
•
·
· ·
3
subfunction code
•
·
•
·
I
I
L
·
•
•
•
· · ·
4
po rt
ID
·
I
~
I
•
•
•
· ·
·
· ·
· ·
5
data Ie ngt h high byte
.
6
data Ie ngt h low byte
where-
log channel I D
Assigned by the host for each transaction. The card firmware will keep the ID with each transaction
until it is completed.
S bit
Used by all non - blocked read device data requests and by the last block of the blocked read device
data request. If the S bit is set, any remaining data in the current read record will be available for
the next read request.
If
the S bit is clear, any data remaining in the current record will be discarded
after the read is completed.
BLK
o
=
non -blocked data transfer
1
=
blocked data transfer
4-2
Advertisement
Table of Contents
