But a couple of minutes earlier you said:
> Well, I guess the proposal was to write a piece of software that a
> TN3270 client connects to and is able to exchange data with it.
Do you really have a 3174? Do you have a real IBM terminal?
Or another way to ask: If you created such a program, what would you be
typing on when you work with the program?
I think Shmuel is talking about https://archive.org/details/bitsavers
And I just noticed my old web bookmark to the 3270 Programmer's
Reference is now gone! I guess I need to keep my 1990 printed manual
which covered in notes and marks and sticky notes :)
On 1/15/2020 8:01 AM, Alexander Huemer wrote:
I am aware RS232 is just a low-level protocol, though, if I decide to
really spend time on this, I have to interface with a 3174 somehow,
low-level. And I wonder which options I have for that, regardless of the
higher protocol layer. I am not questioning that they have to be figured
out.
What is bitsavers?
On Tue, Jan 14, 2020 at 07:59:49PM +0000, Seymour J Metz wrote:
An interface to 3270 displays would be useful only if you had software that
supported 3270 on your platform. Further, is there a real 3270 that is less
expensive than running, e.g., TN3270, on a desktop?
RS-232-C is just a protocol between a serial adapter and a modem; it doesn't
specify, e.g., control characters, packets, going between the modems. B&T,
Ethernet and TR all specify controls at a higher level.
Your best resource for 3270 information is probably bitsavers.
--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
________________________________________
From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> on behalf of Alexander
Huemer <alexander.hue...@xx.vu>
Sent: Tuesday, January 14, 2020 4:52 AM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: Talking to 3270 terminals?
Hi
I am new to this list and would like to discuss an idea and ask several
questions.
* Did anybody ever attempt to 'talk' to 3270 terminals with something
different than an IBM mainframe?
This might sound like a strange idea, though I find it intriguing to be
able to display content on such a terminal and be able to receive
keyboard input from it.
I guess the most straight-forward way to attempt something like that is
to use a 3270 terminal attached to a 3174 or similar and try to talk to
that instead of the terminal itself. I wouldn't know how to interface
with the terminal directly over the coax.
* What's the best available documentation regarding 3174 models and
their features?
I poked around on ibm.com and google but wasn't able to find much. It
seems like there were several different physical-layer north-bound
interfaces for 3174. Bus&Tag, Token Ring, Ethernet, RS232 (if I am not
mistaken, for dial-up connections), maybe others?
Bus&Tag doesn't seem to be a good candidate, it's difficult to interface
with as far as I understand.
Ethernet is way more common these days than Token Ring, though TR NICs
are easy to procure second hand and protocol support under Linux (the OS
I am most savvy with) is in place.
RS232 is easy to interface with also, though then again, I am not sure
if that interface really exists.
* Did the LAN interfaces (Ethernet, TR) talk SNA on layers 2 and 3 or
was there by any chance something going on with TCP/IP? I doubt it
though.
Talking SNA with custom software doesn't seem to be a low-hanging fruit.
From where I stand right now I cannot say how straight-forward the
network traffic between the mainframe and a 3174 is, how difficult it
would be to emulate that protocol with custom software over several
layers.
* Is anybody on the list here able to provide protocol traces from the
link between mainframe and 3174 over any interface? pcap format is
preferred, though anything would be valuable.
I would appreciate any thoughts regarding this topic, especially to the
questions marked with asterisks.
Also, if anything is known regarding a similar thing with 5250 instead
of 3170 terminals, that would be interesting as well.
-Alex
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