Forum Rules and Etiquette

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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.

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Rule 1: 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.

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Rule 2: Stay close to the original topic being discussed
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Rule 3: 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.
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Rule 4: "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:
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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.

Rule 5: 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
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IBM 5155 Keyboard Problem

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    IBM 5155 Keyboard Problem

    I get an IBM 5155 for 250$ wich is a great price, i think.
    Everything is ok, but the Keyboard isnt. If I hit keys, sometimes
    there appears letters on the screen wich arent they, what i've hit.
    So if i press E, there appears EX, and with O, there appears OU.
    What can I do there? (I havent testet it with the CP/M OS, so just with the ROM BASIC because of floppy problems on other computer)

    Originally posted by Manello View Post
    What can I do there?
    It sounds like a faulty keyboard, but I guess that the problem cause could be the keyboard circuitry on the motherboard. It would be good to quickly prove which of the two is the cause.

    If you look inside the 5155, you will see a black cable that runs from the front-panel keyboard connector, along the right side, to the motherboard. You can see the black cable in the photo that is [here]. If you have an XT-class keyboard (an AT-class one will not work), then you could unplug the black cable from the keyboard socket on the motherboard, plug your XT-class keyboard into the socket (when the the 5155 is powered off), and see if that changes the symptom.


      I will try that over the weekend


        That's a cool looking machine there Manello. Very tight and tidy.

        Here's another photo showing the connector at the back:

        I too have a faulty keyboard on my portable 8088 clone (Eagle PC "Spirit"). Fortunately it has an outside DIN connector for an external keyboard, which works fine, but PC/XT compatible keyboards are becoming hard to come by.

        I have heard somewhere, (can someone more knowledgeable than I confirm?), that keyboards have their own ROM which can occasionally develop Alzheimer's. For example, I once had a notebook that forgot how to type a "c". It was NOT a physical switch problem, because shift-c produced a "C" just fine. I couldn't figure it out, and the computer was not worth saving so I stripped it of RAM and its dinky hard drive and threw it away. But I would like to repair the Eagle if at all possible.

        If the ROM thing is true, it would be the second reason popping up today to urge me to buy an EPROM programmer of some sort.


          Keyboard hasnt got his own ROM. If you press a Button, The Keyboard sends a package of Data in bits to the computer. Only keaboards with "extra programmable keys" habe got theyre own rom.
          (The Package of Bits is determinatet of an Matrix in youre keyboard, and it is generatet physical when pressing buttons)


            First rule out the cord being the cause of the problem.
            @ BillDeg:
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              Mine does this kind of thing. Leave it running for ten minutes or so, then give the keyboard and bit of a bash on the bench (not to destruction!), restart and mostly it will work OK until next time you turn it on

              I thought I read somewhere that they have a foam in them that disintegrates and goes dusty, but someone else on there posted that there is no such foam.


                Originally posted by pearce_jj View Post
                Mine does this kind of thing. Leave it running for ten minutes or so, then give the keyboard and bit of a bash on the bench (not to destruction!), restart and mostly it will work OK until next time you turn it on

                I thought I read somewhere that they have a foam in them that disintegrates and goes dusty, but someone else on there posted that there is no such foam.
                All model F buckling spring keyboards have foam padding *inside* the spring assembly.
                Here's a photo of the foam.

                I would wager the problem has to do with the ancient electrolytic capacitors on the controller board. Those should be replaced. They'll probably be axial.


                  At post #5, the OP indicated that he was going to do a simple test to prove that it was indeed the keyboard at fault.
                  In my opinion, I don't think it is worth adding posts to this thread until the result comes in.