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

TTL Parts

  • Filter
  • Time
  • Show
Clear All
new posts

    TTL Parts

    I have several machines in my collection that have been repaired by simply replacing TTL components on various boards.

    One Altair 8800 was fixed when a friend helped me by tracing through the TTL on the front panel to isolate and replace a bad component or two.

    Another Altair 8800 that I recently recieved had bad TTL on both the processor board and the front panel board. Fortunately both of those were socketed so I was able to isolate the bad parts fairly quickly.

    The same was true of an Altos in my collection. One bad TTL part kept the machine from booting.

    With that said, I have two questions:

    1. What causes these parts to go bad? On the second Altair and on the Altos there was no reason for the parts to fail other then pure age. No spikes, static or other abuse could/should have caused it since there was none. The other Altair may have been poked the wrong way at some point.

    2. Having replaced these busted components with newer ones, where can one find older date-coded parts without tearing up other old machines? I'd like to keep my collections as close to pristine as possible which, to me, means keeping the date codes for the parts within reason.

    Any ideas or comments?

    The Vintage Computer and Gaming Marketplace
    The Vintage Computer

    re: TTL Parts


    Older TTL (before mid-1980s) was *extremely* voltage sensitive. While you say there were no "spikes", a warm PSU that allowed the 5V line to drift over about 5.25v could easily have killed them.

    If you really want to stick with original parts, you're going to have to do the same thing NASA do when they want ceramic-packaged 286 and 386 chips for the shuttle program - go on eBay and buy old equipment you can strip them out of!

    Luckily, as TTL was both flaky and expensive in those days, pretty much all of it was socketed, making for easy stripping down of old boards. For bulk TTL, I'd suggest keeping an eye out for old telephone exchange boards circa 1979-1982.

    If you're willing to compromise with newer devices, most machines will accept LS series chips (Low-power Schottky(sp?)) which have a greater voltage latitude, but being based on CMOS technology need to be handled with anti-static precautions. Also, they're no good for circuits where a single output line drives three or more inputs; in that case you need the original part.


      "LS series chips (Low-power Schottky(sp?)) which have a greater voltage latitude, but being based on CMOS technology ........"

      Sorry Charlie, LS TTL chips are not CMOS, nor based on CMOS technology.

      CMOS = Complimentary Metal Oxide Semiconductor technology.

      LS series is still BTL technology.