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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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IBM PC 5150 and IBM PC XT 5160 FAQ

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  • romanon
    replied
    Originally posted by Stone View Post
    My XT has it. I thought it was an emergency exit!
    Emergency exit screwed from outside?

    Leave a comment:


  • Stone
    replied
    My XT has it. I thought it was an emergency exit!

    Leave a comment:


  • romanon
    replied
    Whats the purpose of this hole?

    ibmpcatback.jpg

    I know that on XT-286 serve it for battery pack, but i have it also on my early XT case (05/1983) and i guess that in 1983 nobody think about batteries for CMOS RAM or?

    Leave a comment:


  • romanon
    replied
    Originally posted by tipc View Post
    apologies if this question has come up. Were all 5150 motherboards brown? Were all 5160 motherboards green?
    or dark dark purple

    in my experience: 1981-1984 - green
    1984-1985 - brown
    1985-1987 - dark purple

    Leave a comment:


  • Ozzuneoj
    replied
    Just wanted to mention that you don't absolutely need an expansion chassis to use a hard drive with a 5150. The one I have had a Miniscribe 21MB 3.5" MFM drive working fine with the stock 63.5w power supply, and it's been in the machine since 1987. As long as the power draw isn't too much for the PSU it works fine, even for booting. Newer or smaller drives are more likely to work.

    This isn't exactly a secret, but there doesn't seem to be much mention of using HDDs with these so I figured I'd chime in.

    Leave a comment:


  • Timo W.
    replied
    No, they can be either brown or green.

    Leave a comment:


  • tipc
    replied
    apologies if this question has come up. Were all 5150 motherboards brown? Were all 5160 motherboards green?

    Leave a comment:


  • Tyler Durden
    replied
    I have an IBM 5160 that has a BIOS ROM U18 with IBM part number 500026. The ROM is a ceramic package with a gold lid.

    The motherboard is also slighly different than the two shown here:
    http://www.minuszerodegrees.net/5160..._revisions.htm

    Mine has an Intel 8088.

    It also has the number 4073 stamped to the right of the silkscreen "64 - 256KB SYSTEM BOARD"


    I read that nobody has seen one of these motherboards in the wild and have not seen this BIOS PROM.

    Is this system one of the first beta XT's?

    Leave a comment:


  • mwin
    replied
    I got one of these letters with a 5150 I got from kijiji. Though I share it here in case someone wants a copy.

    Dear New Owner.jpg

    Leave a comment:


  • pearce_jj
    replied
    Originally posted by sergey View Post
    I was wondering about the purpose of the 74LS32 installed in U101 (which is a spare location). Some boards have it, some don't.
    Apparently the explanation is following: AMD DMAC (9517 aka 8287 by its Intel's designation) had a bug, probably something related to CPU writing to the DMA while a DMA operation was in progress. This bug was fixed by adding that 74LS32, some wires, and probably a few cut traces on the PCB.
    Very interesting - thanks for posting this.

    Leave a comment:


  • yuhong
    replied
    Originally posted by Beerhunter View Post
    Not the case. This myth that non-IBM Personal Computers were free of IBM royalties until Micro Channel came along is just that - a myth.
    I actually read some of the old InfoWorld etc articles on this matter, and one article said that it tended to be 5% for MCA systems once the patents were granted vs ~3% for PC AT compatibles.
    Last edited by yuhong; April 20, 2013, 04:46 PM.

    Leave a comment:


  • sergey
    replied
    Originally posted by dongfeng View Post
    64-256kB 5150:
    I was wondering about the purpose of the 74LS32 installed in U101 (which is a spare location). Some boards have it, some don't.
    Apparently the explanation is following: AMD DMAC (Am9517 aka 8237 by its Intel's designation) had a bug, probably something related to CPU writing to the DMA while a DMA operation was in progress. This bug was fixed by adding that 74LS32, some wires, and probably a few cut traces on the PCB. Interestingly enough the board on the picture appears to have an Intel made 8237, and still has the U101 patch work.

    Here is the IBM ECA that mentions this issue: http://www-05.ibm.com/services/ecalib/doc/5150-005.txt. Note that they call DMAC a "processor" .

    Other threads mentioning this bug / fix:
    http://www.vintage-computer.com/vcfo...revision-board
    http://www.vintage-computer.com/vcfo...IC-Differences

    Newsgroups references:
    http://groups.google.com/group/net.m...3ab53bc25ad3c6
    https://groups.google.com/group/comp...c8573a0adefa15

    5150-related ECAs (not sure if they are mentioned elsewhere):
    http://www-05.ibm.com/services/ecalib/doc/5150-001.txt
    http://www-05.ibm.com/services/ecalib/doc/5150-002.txt
    http://www-05.ibm.com/services/ecalib/doc/5150-003.txt
    http://www-05.ibm.com/services/ecalib/doc/5150-004.txt
    http://www-05.ibm.com/services/ecalib/doc/5150-005.txt
    http://www-05.ibm.com/services/ecalib/doc/5150-006.txt
    Last edited by sergey; April 20, 2013, 03:38 PM.

    Leave a comment:


  • Beerhunter
    replied
    Some of them tried. The problem for the clone manufacturers was that IBM owned some of the fundamental patents for building a PC, be it ISA or Micro Channel. In fact at the time of announcement, the Micro Channel patents were still pending and so Micro Channel machines were licensed for EXACTLY the same set of patents as ISA boxes. BTW, IBM only charged licences for complete PCs, motherboards and adapter cards were license free.

    At the time it really irked me that IBM failed to explain all of this properly. I well remember that I found out later, that on the 2nd August 1987, while I was briefing one set of journalists about Micro Channel and how it was still open architecture (In fact we documented Micro Channel much better than we ever did with the PC/PC AT.) one of our moronic executives who would not have recognised a PC if it bit him was threatening all and sundry with law suits!

    Leave a comment:


  • geneb
    replied
    Did any of them refuse to pay the royalty? (I'm assuming you're referring to clone motherboards and not ISA cards...)

    g.

    Leave a comment:


  • Beerhunter
    replied
    Originally posted by IBMMuseum View Post
    But when they saw competitors making the full base systems a licencing process came into place later for the PS/2s.
    Not the case. This myth that non-IBM Personal Computers were free of IBM royalties until Micro Channel came along is just that - a myth. IBM charged royalties on the early PCs as well. At the time the royalties system was highly confidential. So much so that here, in the UK, some manufacturers were quite surprised to be asked to pay. How do I know? I was there. I even remember the names of the guy in EMEA and the one in Boca who were responsible for collecting royalty payments.

    Leave a comment:

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