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
  • 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.

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.
  • 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.

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:
  • "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.

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.
  • 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.
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New TestFDC Results Registry

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    Now available as a plaintext export:

    The linked plaintext export is dynamically generated and contains the same information as the HTML view. I finally got some testing done myself and have some new entries to get in this weekend!
    Check out The Glitch Works | My Retro Projects | Vintage Computer Services | Glitch Works Tindie Store -- Vintage Computer Kits and More


      Just finished integrating a tool that lets me do approvals in a less manual fashion -- I'd been doing it by hand in the DB until now. Better tools should mean faster/more frequent approvals!
      Check out The Glitch Works | My Retro Projects | Vintage Computer Services | Glitch Works Tindie Store -- Vintage Computer Kits and More


        Hey thanks for bumping this! Noticed my Win98 box's AP5T board was on the list and it motivated me to give it a run, and it supports FM on the built-in FDC like a freaking champ~!

        (Also IMD works perfectly inside Win98SE GUI)

        EDIT: actually while IMD works just fine, Win 98 REALLY didn't like me accessing the FDC directly without its knowledge. When I went back to access the drive through 98 it made some heinous seeks and bounced off the limiter (at this point I had a standard MFM DOS formatted disk in there and IMD was no longer running)
        Last edited by maxtherabbit; July 18, 2020, 07:43 PM.


          Simply set IMD to execute in real mode in Win98SE.
          Reach me: vcfblackhole _at_ protonmail dot com.


            I've been meaning to share some research I did on good FDCs a while back.

            Most enthusiasts know about the good NatSemi FDCs, but there were also good ones made by ALi (Acer Labs, Inc.). Their FDCs appeared in both their Super I/O chips and Southbridge chips. The southbridge chips with good FDC support are the M1535 and M1543, including variants (see below). These southbridges were paired with multiple generations of northbridges, thus it’s potentially possible to find a motherboard up to Socket 478 with good floppy support. In reality, I’ve not been able to find any beyond about Socket 370 however. ALi was overtaken by VIA and SIS after the Socket 370 era and lost market share. ALi’s later southbridges, M1563 and M1567, don’t have floppy support.

            ALi also partnered with PC Chips, and several generations of their Aladdin chipsets were re-branded on PC Chips boards. Any of these PC Chips chipsets should have good ALi FDCs in their southbridge: BXcel, HX Pro, Super TX, TX Pro, TX Two, and GFXpro. I own a PC Chips M754LMR+ (GFXpro) and the FDC is great.

            It's tedious to sort out all the various labels and generations of their southbridges -- for example, there were M1535, M1535+, M1535D, M1535D+, HT1535+, HT1535D+ -- but from what I can infer, any of them with a "3" or "4" as the 3rd digit should have the good FDC cores. For example, the GFXpro southbridge is HT2543CB1.

            The Acer Super I/O chips are less documented (and I need to do more testing), but the M5105 was commonly found on ISA cards in the early ‘90s and has good floppy support. The Diamond Flower MIO-400KF cards I've come across use this chip and are often cheap on eBay.

            Hope that helps people sort out their own stock and/or shop for boards with good FDCs.


              SMSC chips are generally very capable as well.
              Reach me: vcfblackhole _at_ protonmail dot com.


                Thanks for your updates TestFDC.

                I did some test yesterday and have a question.

                CA9277B Advanced Super I/O Controller with N82077SL FDC.

                My problem sometimes is to find the correct result as on 360k floppy SD at 250 failed and on HD-floppy it was not tested.

                So I interpreted the Result as follows
                 Data  Rate
                 250  300  500
                 SDX  SDX  SDX
                 FPF  PPF  PPF 
                Hardware SlotCPU AMD386-33  , Matrox VGA, 3C509 NIC
                A: 360kb
                Report on FDC capabilities, issued 21/06/2020 19:43:34:
                [B]Single-Density at 250 kbps ............................ Failed[/B]
                Single-Density at 300 kbps ............................ Not tested
                Single-Density at 500 kbps ............................ Not tested
                Double-Density at 250 kbps ............................ Passed
                Double-Density at 300 kbps ............................ Not tested
                Double-Density at 500 kbps ............................ Not tested
                Double-Density at 250 kbps / 128 byte sectors ......... Failed
                Double-Density at 300 kbps / 128 byte sectors ......... Not tested
                Double-Density at 500 kbps / 128 byte sectors ......... Not tested
                B: 1,2MB
                Report on FDC capabilities, issued 21/06/2020 19:49:47:
                [B]Single-Density at 250 kbps ............................ Not tested[/B]
                Single-Density at 300 kbps ............................ Passed
                Single-Density at 500 kbps ............................ Passed
                Double-Density at 250 kbps ............................ Not tested
                Double-Density at 300 kbps ............................ Passed
                Double-Density at 500 kbps ............................ Passed
                Double-Density at 250 kbps / 128 byte sectors ......... Not tested
                Double-Density at 300 kbps / 128 byte sectors ......... Failed
                Double-Density at 500 kbps / 128 byte sectors ......... Failed


                  I believe that I noted the inconsistent issue a couple of years ago. I believe I uploaded a much simpler version of the tool at the time.

                  But the Intel 82077AA-1 definitely has issues with FM and doesn't do 128-byte MFM, period.
                  Reach me: vcfblackhole _at_ protonmail dot com.