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Thread: 3274 21C Worth Picking Up?

  1. #21
    Join Date
    Jun 2018
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    Quote Originally Posted by Al Kossow View Post
    At least the 3191s have model 'M' keyboards, which aren't that uncommon or collectable.
    Haven't checked on this thread in a while, but its nice to hear that almost all of these terminals and controllers found a good home. I bought one of the 3191's because it had a model F 122, not a model M 122, but didn't know how I could get the terminal to work with a modern computer or what I'd use it for. I've seen people use 1970's serial terminals with modern Linux machines which looks really cool, but IBM's use a different protocol. So, what do people do with 3191's?

  2. #22
    Join Date
    Sep 2006
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    Quote Originally Posted by willmurray461 View Post
    I bought one of the 3191's because it had a model F 122
    I was the other bidder. $66 was a good price for a clean Model F kb.

    So, what do people do with 3191's?
    They could be used with the Hercules IBM mainframe emulator, but the connectivity is complicated.

    Currently, you need a fairly complicated and expensive box like an IBM 3174 to translate TN3270 protocol
    (the default mapping of the mainframe 3270 terminal protocol to TCP/IP in Hercules) to the CUT (Control Unit Terminal)
    coaxial protocol that the 3278/3178/3191s use. It's actually more involved than just protocol translation, the
    things we think of as what goes on inside of an ASCII terminal are split between the CUT and the 3174 'Establishment Controller'.

    It can't be any old 3174; most of them were sold as remote devices with low-speed serial connections.
    It has to have an ethernet (or token-ring that could talk TCP/IP) because TN3270 runs through TCP,
    so you need a fairly big/expensive 3174 that could support those interfaces, and only the larger models support
    TCP/IP networking.

    Most people don't bother with trying to get a real IBM or third party CUT to work because of this.
    It is MUCH easier to just run a TN3270-capable CUT emulator, of which there are many.

    I'm starting to investigate what it would take to do the equivalent TN3270 to CUT bridging on a Beaglebone.
    You really don't need the capabilities of a 3174 just to talk to one CUT.

    There are also some crazy hacks you could come up with once you have a Linux box that could talk
    directly to a CUT. In theory, you could make them work like a ordinary serially connected terminal.
    I was thinking it would be a cute hack to be able to play 'worms' or 'rogue' on one.

    Here is an overview of this style of terminal:
    https://en.wikipedia.org/wiki/IBM_3270
    Last edited by Al Kossow; October 5th, 2018 at 07:49 PM.

  3. #23

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    Quote Originally Posted by Al Kossow View Post
    I'm starting to investigate what it would take to do the equivalent TN3270 to CUT bridging on a Beaglebone.
    You really don't need the capabilities of a 3174 just to talk to one CUT.
    I was thinking about a similar project recently. I figured the DP8340/41 chips do almost all of the hard work involved with the serial communication. The CUT protocol itself though seems to very simple judging by the limited information I was able to find out about it.
    But I wanted to get a terminal working with a 3174 first.

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