The following traces were taken Using a Telenex Autoscope tee'd in to a link
. . . . House
. terminal 3274 . ------ . . ------ ------
. - ---- . | | . . | | PW | |
. -/ +-| +-.---| 3006 +--..........--| 3010 +-------| Host |
. +---| +----| . +------| . . +------| | +------|
. . . . |
................... .......... ---+-----
| |
| our |
| tester |
+---------|
The trace is read as follows:
sync timestamp hex coding of
character | data on line
| | |
v v v
from 3010 to host - High BCD --> FFs314:58:5844772FF
low BCD --> FFy2 00FFDFF
from host to 3010 - High BCD --> FFFF FFFFFFF
low BCD --> FFFF FFFFFFF
-------------------
21 - Polling trace
This shows the situation where the host is polling but neither end has anything to send.
- (A) Host polls with a general poll (control unit 40)
- (B) Control unit has nothing to send so sends EOT
- (C) Host sends EOT to end sequence
22 - Polling with data transfer - trace
This shows the host polling and this time the cluster controller has some text to send.
- (a) host polls with a general poll
- (b) terminal sends text.
<---------- 3270 data stream --->
---------------------------------------------------------------
PAD SYN SYN | STX | CU | Dev | AID | cursor | SBA: | text | ETX | BCC |
'55' | | add | add | enter | address| |=help | | |
+-----+-----+-----+-------+--------+---------+------+-----+-----|
02 40 40 7D C8F4 11C7E8 AAAB
- (c) Host acknowledges
- (d) Terminal ends transaction
23 - Selection - trace
This time the host has some text to send to the cluster controller.
- (a) Host wishes to send data to terminal so it selects control unit.
- (b) Terminal acknowledges.
- (c) t sends a message 193 bytes long.
<---------- 3270 data stream --->
| PAD SYN SYN | STX | ESC | WRITE | WCC | SBA: | start | text.. | ETX | BCC |
| '55' | command | field | |||||||
| 02 | 27 | F1 | C1 | 114A40 | 1D |
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