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

Commodore PC 10-iii/ PC 20-iii boot issues

  • Filter
  • Time
  • Show
Clear All
new posts

    Commodore PC 10-iii/ PC 20-iii boot issues

    Hi all,

    I'm new here and I have done some searching, but I cannot find an answer to this. I recently picked-up a Commodore PC 20-iii and i am having some trouble getting it to boot. I plug everything in and turn it on and I can hear the power supply fan and HDD spin up and I get 2 beeps from the HDD and the CAPS LOCK, etc... lights on the Keyboard flash and that's it. The floppy drives don't light up or make any noise and I do not get any output from the composite port.

    I have the video output connected to a converter box to switch it to HDMI so I can view it on my monitor, and I appear to get a video signal (the no signal indicator goes away and the screen goes from blue to black), but there is no information, just a black screen. I tried hooking it up through my receiver to view it on my TV, but again no luck.

    I checked the voltages on the power supply output and I have +4.68v and +/- 11.7v, so I think its ok, but just in case I picked up a new ATX power supply and tired connecting it to the HDD (i still need to make an adapter to hook it to the board) and again it spins up and I get 2 beeps. I know the beeps are from the HDD since it's the only thing hooked up.

    I tried booting with nothing connected and again just a black screen and no beeps or output.

    I reseated all of the chips that I could and still nothing.

    I checked the battery and its not leaking and had 3.7V. I have an external battery try that I can wired in if needed, but I'd rather not cut the original battery off if I don't need to.

    I'm not sure what to try next. I have an RGBi monitor, but it requires 220v and don't have a 220v power source right now. I don't have an ISA video card that I can try at the moment.

    Any thoughts?
    Last edited by Postie0717; May 22, 2021, 04:53 AM. Reason: Added tags

    Before this PC will boot from FDD/HDD at all, it will show several messages on the screen. So the first thing that has to be done is to find out if the PC sends those messages. Is there a possibility to make sure that this converter box works fine by testing it with another computer?
    Another thing: my PC20-III only gives some beepish sounds after all these messages but before starting to boot. It certainly are not two beeps.

    Where do you live? Not having 220V means not living in Europe which limits me helping you with physical parts.
    With kind regards / met vriendelijke groet, Ruud Baltissen


      Thanks for the assistance Rud.

      I have confirmed that the converter from composite to hdmi does work, i tested it with my Wii, so it looks like my first step will be getting a video signal. Any ideas? I'm still iffy about the power supply. I know it tested ok, but I'm still going to replace it with a new one once the parts come to adapt the new power supply to the old connector.


        Originally posted by Postie0717 View Post
        Any ideas?
        To be honest? None. I have several of these machines and so far I only ran into minor problems like bad ROMs or RAMs, broken CPU and empty built-in batteries of the RTC. No video problems so far. And if I cannot reason what the error is, the next thing that I would do is swapping ICs with a good board. The moment that that one stops working, I think I found the culprit. And finding the bad IC probably does me good: I don't have spares except the good ones of other unrepairable boards.

        With kind regards / met vriendelijke groet, Ruud Baltissen


          Thanks for the info Ruud.

          Ok, so I have confirmed that the power supply and the video convertor both work just fine. I picked up another machine, verified that it worked, and used it as a test bed for the power supplies and the video out. I'm beginning to suspect that its a video issue with the original machine. I'm wondering if its a PAL vs NTSC issue? I didn't think it would matter for the composite out, but i might be wrong. Would the RGBi out work better? Also i tested the HDD in the working machine and it still beeps twice and i get a no boot disk found error. Interestingly after the ram test, but before the boot disk error, a 1701 code pops up. Any ideas what this means? Thanks.


            CGA composite output is always either NTSC or black and white, but never PAL.
            Since you didn't mention any battery leakage, I assume that there is none. I have read that interrupted traces to the floppy controller are not uncommon in those machines in the presence of battery leakage.


              Originally posted by Postie0717 View Post
              ... a 1701 code pops up. Any ideas what this means? Thanks.
              That means that the HDD does not work.

              FYI: I use my PC20-III in combination with XT-IDE. It has one 20 GB HDD (only 8 GB available of course) and a CF card slot. I use that one to exchange data with other machines.

              With kind regards / met vriendelijke groet, Ruud Baltissen



                Originally posted by Postie0717 View Post
                ... a 1701 code pops up. Any ideas what this means? Thanks.
                Originally posted by Ruud View Post
                That means that the HDD does not work.
                In many other computers, 1701 points to a problem hard drive system (controller/drive/cables/power/slot).
                See here for some ideas.