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.

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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Favorite memory check routines

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    Favorite memory check routines

    Nothing says "S-100" quite like memory problems, which seem to crop up unexpectedly and lead to mysterious faults and crashes. My latest escapade has involved DDT suddenly not running on a 63K CP/M 1.4. I think I've narrowed it down to an 8K board addressed at C000-DFFF.

    I'm running a bunch of static ram boards in an IMSAI. Nearly each and every one has had a bad 2102 chip or two. Sometimes bad bits can be detected by the front panel, but other times the memory issues only crop up when running a program or (presumably) during DMA by the disk controller. This is with an 8080 board. Apparently things can get worse running a faster Z-80 CPU.

    I've used a number of memory check routines, ranging from the December 1976 Interface Age program, to other simple routines I've cobbled together, and going as far as comparing memory dumps written to disk then transferred to a unix box to examine with hexdump when the front panel and memory routines have failed to come up with anything.

    Since things seem to get weird with the (Tarbell 1011A) disk controller, I'm thinking of writing a routine that checks with reads and writes to disk (assuming the drives and controller are working... sigh...) (note: I think I've excluded that possibility in the present case.)

    I'm looking for recommendations and source of favorite memory routines out there. What do you use and why?


    Hi Eric,

    I feel your pain as I've had similar problems with my 2102 RAM boards. Recently, I've been using Martin Eberhard's MEMON ROM monitor with the additional memory test program. It's been great at finding faulty RAM although I've found that I sometimes have to run several passes for a fault to show up. Using a ROM based program means I can pull pretty much everything else out the system.



      The most intensive is galpat but march C or variants work well enough. For static memory you might want to include a retention test as it might surprise one to know that there are faults that make a static RAM act like a DRAM.


        Yes if the memory crashes in a zone used by CP/M all hell breaks loose.

        I have been running 48k of RAM in my SOL-20 & CP/M. Before I got all the hardware bugs out of the three 16k RAM boards, I had all kinds of trouble.

        Most of the issues (aside from some faulty delay lines) were due to poor connections from the corroded dissimilar metals on the IC pins & sockets.

        Once repaired the problems vanished. Each IC pin must have the corrosion removed where it interfaces with the socket and each socket pin must be checked for spring tension with an IC pin taken from a donor IC and soldered to a small arm to feel the socket pin tension on every socket. (If the RAM IC's and others are not in sockets, you are probably better off).

        The memory test program I used to check the entire memory from 0000h to BFFFh, is from Mike Douglas's site. It hides at CAC0h on the main board ram.But its address can be altered:

        One advantage; it relentlessly cycles and throws up the faulty addresses, but because of this, it makes it very easy to check the card with the scope to find defective IC's & socket connections etc while its doing its checking.

        (PS: TI sockets grip the IC pins from side to side, while other brands do it across the flat part of the IC pin. It is important to know which types of IC socket you have so the IC pins can be cleaned up on the surface that interfaces with the socket pin. The corrosion often needs to be scraped off the IC pin with a rectangular edge metal tool and then finished with 2000 grade paper.Every pin on every IC in a socket requires attention. Just washing the pins or re-seating the IC's won't work as the layers are crystalline oxides which are electrical insulators)
        Last edited by Hugo Holden; June 6, 2019, 05:40 AM.