Forum Rules and 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.

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.

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.

Rule 2: Stay close to the original topic being discussed
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  • 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.

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.
  • 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.
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  • Use the Private Message system for posts that are targeted at a specific person.

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
  • Use Google, books, or other definitive sources. There is a lot of information out there.
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My Altair 8800a project

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    My Altair 8800a project

    I thought I share my work:

    Over the past three years I've made some S100 boards for my Altair 8800 build. Two years ago I've bought an empty optima case from Ebay. To make
    a working 8800a computer I worked on the PCB's and the frontpanel (artwork). First the artwork. Luckily there's a good scan online ( for
    designing a new frontpanel. I've made a new version in GIMP by selecting, tracing and pixel editing to get a clean frontpanel for printing. I think it's a nice attempt if I say so myself.

    I've printed the frontpanel on aluminum so there's a metal feel to it. I've integrated the logo strip because the printing company (photo on aluminum) can print transparent pngs.


    Then the pcbs. When I started with the pcbs I never made anything in Kicad. Now I'm somewhat of a pro . Some of the schematics from MITS are messy (as you probably know) so for
    example with the 8080 CPU I've bitmap converted the pcb scans to trace the tracks after I've made the schematic from the manual. I did this with every pcb. The boards are not a replica or a pixel
    perfect clone. This is because I chose for a schematic / PCB approach rather then a scan / gerber. an advantage is that you can easily make changes. (For example, A 8080 CPU pcb change with the clock mod)

    8080 CPU (works, KiCad replica. needs cpu clock tuning. Schematic cleaning necessary):


    Front Panel (works, KiCad replica. Schematic cleaning necessary):


    For the main board I've used scans available on the internet. This board is also remade with Kicad:


    Then I needed ram. I like using old boards and old ICs so I started with a 1k static ram board. It's a simple board but I don't have the pcb scans. The board is finished and working. Protect / Unprotect works.
    MITS 1k static ram board (works, Kicad new design based on pictures. No original traces):


    For the PSU I used an original PS DB supply pcb and bought transformers to use the system with 220volt. I've scans available when I stripped the PCB but it's better to use a switching power supply these days.
    I worked on my Altair for a very long time. Now I'm at the point where I can play kill the bit on my machine. I'm not a electrical engineer. Just a network IT-er with a passion for old machines. Keep that in mind when looking at the Kicad images

    At this moment I'm working on serial communication. The schematics for a 2SIO board are messy and I've made a prototype from the manual with problems. I would love to get pcb scans from a bare pcb. That would be really great. In the last couple of weeks I've made two
    other serial boards. The Solid State Music IO-4 and a MITS SIO-A board. These two boards are arrived last week and I'm waiting on the last ICs to test the boards. The traces on the IO-4 are autotraced so not that nice. For now that's enough.



    Solid State Music IO-4:


    The last project I'm working on is the Tarbell Cassette Interface. I've a finished schematic plus a PCB traced from the manual (very difficult thing to do!). The KCS mod is not included. I need to test this pcb in the coming weeks but a working serial board is my priority.

    Tarbell Cassette Interface 1001:


    I don't know if people are interested in the PCBs. I will setup a site when people are interested. I know Grant's very nice clone is neater but a more affordable alternative is desirable I think. If you do not want to work with 74xx logic, I would like to refer to the Altair 8800c
    Maybe someone can help me with bare pcb scans from 1k static ram, SSM IO-4 or the 2SIO card. I would love to trace those boards to Kicad perfection and also find the problem with the 2SIO board.

    Martijn from Holland.

    I had been considering doing something like this myself so it's fun to see what you have done here.

    More affordable alternative is definitely something I am interested in also.

    Quite a project for a first go a KiCad!


      Thank you. I'm sorting the files and cleaning up. Maybe a Git repo, I don't know yet.

      It's been fun to build something like this. I was lucky to buy an optima case. a working system is way too expensive for me. The problem
      is a nice alternative case. Some people used 19inch racks but I don't like that.

      I forgot to add some pictures of the system:


        Lots of good work already. Fun!



          Will you be posting your KiCAD files?


            Thanks for the nice reactions. It's a lot of work. The past few weeks I've been working on my SIO-A board. No luck. I think the card is working but when I use the test program from the computes notes I can select the card on address zero but
            the input instruction gives 174 and not zero or one. I need to debug the card. Maybe a wrong clock signal? I worked my way to all the errata sheets and I think I've done all the changes...

            I've included links for the Gerber files for the CPU and frontpanel for now. Let me know if you'll need other boards or if there are any problems. I need
            to setup a site / Github for all the files. The Kicad files (schematic) are so messy to release just yet

            The SSM or Tarbell is a work in process so I'm not ready to release them. I don't know if the cards work yet.

            Is there someone willing to de-solder a SIO-A (rev1) or 2SIO board to make a scan with a scanner? A high resolution scan with the components would also be nice.