AM3270/TR3271 Reference Manual

AM3270 Product Environment
A Closer Look at AM3270
3–8 086705 Tandem Computers Incorporated
Figure 3-5. READ Operation
010
CALL READ
1
*
*
Delay for POLLINT
Send ACKn
Send [RVI]
?
?
?
Err=173
Err=100
or
Err=179 it
status in response to a select
and application buffer is
improper.
2
?
3
Err=0
Save Status
?
?
Err=177
2
3
(subdevice added to poll list)
(polling)
wait for response
no
yes
no
yes
list done
no
yes
retry
no
yes
Device End
yes
no
Device Error
no
yes
Specific Poll
4
Err=171
?
1
no
yes
retry
POLLINT=O
Send [NAK]
Text
(IF)
EOT
(IF)
Text
w/Error
(IF)
Overrun
(IF)
Status
Msg
(IF)
No
Resp
(IF)
3
2
3
3
WRITE Operation
Figure 3-6 illustrates the action of AM3270 in response to a WRITE request. This
example assumes that the line is idle and that the subdevice has the CRT protocol
assigned to it.