Announcement

Collapse

Forum etiquette

Our mission ...

This forum is part of our mission to promote the preservation of vintage computers through education and outreach. (In real life we also run events and have a museum.) We encourage you to join us, participate, share your knowledge, and enjoy.

This forum has been around in this format for over 15 years. These rules and guidelines help us maintain a healthy and active community, and we moderate the forum to keep things on track. Please familiarize yourself with these rules and guidelines.


Remain civil and respectful

There are several hundred people who actively participate here. People come from all different backgrounds and will have different ways of seeing things. You will not agree with everything you read here. Back-and-forth discussions are fine but do not cross the line into rude or disrespectful behavior.

Conduct yourself as you would at any other place where people come together in person to discuss their hobby. If you wouldn't say something to somebody in person, then you probably should not be writing it here.

This should be obvious but, just in case: profanity, threats, slurs against any group (sexual, racial, gender, etc.) will not be tolerated.


Stay close to the original topic being discussed
  • If you are starting a new thread choose a reasonable sub-forum to start your thread. (If you choose incorrectly don't worry, we can fix that.)
  • If you are responding to a thread, stay on topic - the original poster was trying to achieve something. You can always start a new thread instead of potentially "hijacking" an existing thread.



Contribute something meaningful

To put things in engineering terms, we value a high signal to noise ratio. Coming here should not be a waste of time.
  • This is not a chat room. If you are taking less than 30 seconds to make a post then you are probably doing something wrong. A post should be on topic, clear, and contribute something meaningful to the discussion. If people read your posts and feel that their time as been wasted, they will stop reading your posts. Worse yet, they will stop visiting and we'll lose their experience and contributions.
  • Do not bump threads.
  • Do not "necro-post" unless you are following up to a specific person on a specific thread. And even then, that person may have moved on. Just start a new thread for your related topic.
  • Use the Private Message system for posts that are targeted at a specific person.


"PM Sent!" messages (or, how to use the Private Message system)

This forum has a private message feature that we want people to use for messages that are not of general interest to other members.

In short, if you are going to reply to a thread and that reply is targeted to a specific individual and not of interest to anybody else (either now or in the future) then send a private message instead.

Here are some obvious examples of when you should not reply to a thread and use the PM system instead:
  • "PM Sent!": Do not tell the rest of us that you sent a PM ... the forum software will tell the other person that they have a PM waiting.
  • "How much is shipping to ....": This is a very specific and directed question that is not of interest to anybody else.


Why do we have this policy? Sending a "PM Sent!" type message basically wastes everybody else's time by making them having to scroll past a post in a thread that looks to be updated, when the update is not meaningful. And the person you are sending the PM to will be notified by the forum software that they have a message waiting for them. Look up at the top near the right edge where it says 'Notifications' ... if you have a PM waiting, it will tell you there.

Copyright and other legal issues

We are here to discuss vintage computing, so discussing software, books, and other intellectual property that is on-topic is fine. We don't want people using these forums to discuss or enable copyright violations or other things that are against the law; whether you agree with the law or not is irrelevant. Do not use our resources for something that is legally or morally questionable.

Our discussions here generally fall under "fair use." Telling people how to pirate a software title is an example of something that is not allowable here.


Reporting problematic posts

If you see spam, a wildly off-topic post, or something abusive or illegal please report the thread by clicking on the "Report Post" icon. (It looks like an exclamation point in a triangle and it is available under every post.) This send a notification to all of the moderators, so somebody will see it and deal with it.

If you are unsure you may consider sending a private message to a moderator instead.


New user moderation

New users are directly moderated so that we can weed spammers out early. This means that for your first 10 posts you will have some delay before they are seen. We understand this can be disruptive to the flow of conversation and we try to keep up with our new user moderation duties to avoid undue inconvenience. Please do not make duplicate posts, extra posts to bump your post count, or ask the moderators to expedite this process; 10 moderated posts will go by quickly.

New users also have a smaller personal message inbox limit and are rate limited when sending PMs to other users.


Other suggestions
  • Use Google, books, or other definitive sources. There is a lot of information out there.
  • Don't make people guess at what you are trying to say; we are not mind readers. Be clear and concise.
  • Spelling and grammar are not rated, but they do make a post easier to read.
See more
See less

Vintage analog computer in surplus auction at University of Texas

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Vintage analog computer in surplus auction at University of Texas

    There is an interesting analog computer for sale in the current auction at the University of Texas in Austin. EAI model TR-20. The auction uses online bidding which ends on Friday Sept 20 for this item. The current bid price of $35 might be just for salvage value for the materials.

    swico_auctions_43886_1.jpg

    swico_auctions_43886_2.jpg

    https://swicoauctions.com/online/26/item/43886

    Searching the internet leads me to think that this computer might be from the 1960s or 70s. These computers where programmed with jumper cables and knobs. I understand that these computers were used to solve complex mathematical problems with analog electrical signals and that the output could be recorded on paper with an analog plotter.

    Lloyd

    #2
    This EAI TR-20 unit was delivered to my house earlier this week. It had been sitting in Austin for over a year I believe while seller waited for me to figure out how to get it shipped here without too much additional cost. It came with a bunch of patch cables, two function cards, and original power cable tucked inside the drawers.
    More fun.

    Comment


      #3
      Wow! That brought back some memories. I used an Analog Computer in college in the late 60's as part of a lab associated with a Feedback Control System class. As I recall it was hooked up to a huge plotter. I hope you can get it all working without to much trouble.
      -Dave

      Comment


        #4
        Which modules does it have? How many multiply modules? Also does it have any of the diode waveform modules?
        Dwight

        Comment


          #5
          Very cool. We had one of those in the EE dept. at University of Vermont in 1970. I still have 'Basic Analog Computation' by Gerald Peterson, which was our course textbook. Brings back memories.

          Comment


            #6
            It seems to be fairly loaded.

            3 quarter square mult 7.045
            3 dual repetitive integrators 12.1115
            1 tie point network 12.267
            1 variable diode function generator group(16.308 vdfg readout, 2 vdfg modules in the trays underneath)
            1 display network 12.987
            1 relay comparator 6.143
            1 dual function switch group (function switch assembly, readout 12.264)
            1 attenuator group 2.128 (attenuator panel, readout 12.265)

            repeat operation expansion group (repeat operation timing unit 36.082, high speed control panel 20.532)

            10 dual dc amps 6.712
            10 dual attenuator 42.187

            10.179 power supply
            43.037 reference regulator
            6.282 dual dc amp
            tr20.png

            Comment

            Working...
            X