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.
See more
See less

5160 BIOS Source Code

  • Filter
  • Time
  • Show
Clear All
new posts

    Originally posted by Plasma View Post
    The EGA BIOS should be initializing the video memory. The IBM BIOS doesn't check video memory on the EGA either since it is not EGA-aware.
    I'm wondering if the problem could be that the video bios is not completing it's initialization since the Hard drive controller bios is coming up immediatly after. As I mentioned previuosly, the IBM bios does the mem count in between. If I'm right, a short delay after the video bios comes up should do the trick. What do ya think?


      I don't think that's the problem. The video BIOS will not return control back to the system BIOS until it's done initializing. The hard drive BIOS init is not interrupting it.

      I have attached a small program which will dump your system memory to a file. Can you do a cold boot, load DOS and nothing else, then run "memdump cold.bin". Then do a cold boot again, wait for DOS to load, hit ctrl+alt+del, load DOS again, and run "memdump warm.bin". Attach cold.bin and warm.bin and I will see what's different.


        I made the memory dump files but they are to large to attach here. The forum has a silly limit of 97.7K and these files are bigger than that, even zipped up. If you send me a PM with your EMAIL address, I can send them to you as an email attachment.


          Email sent. Let me know if you find anything. No big rush on this as the Super XT BIOS is really working very well asside from this one issue.


            For anyone else interested, we finally tracked the problem down to UMBs not being cleared before the EGA BIOS was initialized. This is now an option in the latest version.



              Plasma is to be commended here!
              Super PC/Turbo XT BIOS 2.5 is up and running on my "Hot Rodded" IBM 5155. I have yet to find a problem with it. It speeds up the boot process considerably and appears to be completely compatible with the latest IBM Bios, in that all the apps and games that I ran with the IBM Bios run Perfectly with Super PC/Turbo XT BIOS 2.5
              I haven't documented it, but I think most apps seem to load and run faster than they did with the IBM Bios. Some time I'll have to run some tests with a stopwatch to find out for sure.

              Thanks Plasma for all your hard work and patience!

              p.s. I decided to set UMA_START = 0A000h, UMA_END = 0F000h so that if I decide to use my CGA adapter instead of the EGA Wonder, I can map more upper memory for UMB without having to change the Bios. I think it slows the boot process slightly by attempting to clear memory that's not mapped, but probably only a second or two.


                Glad to hear there are no more problems

                If you are using a CGA, the optimal setup would actually be to set MAX_MEMORY = 736, that way conventional memory can extend all the way to B800 (assuming you modify your GAL to map A000-B7FF to system RAM).


                  Originally posted by Plasma View Post
                  Glad to hear there are no more problems

                  If you are using a CGA, the optimal setup would actually be to set MAX_MEMORY = 736, that way conventional memory can extend all the way to B800 (assuming you modify your GAL to map A000-B7FF to system RAM).
                  The GAL is programmed to map several different regions based on the way the motherboard switches 3 and 4 are set. Right now, they are both open so it maps 640k of base memory plus segments D and E. If sw 4 is closed and sw 3 is open, it maps 640K base plus Segments A, D, and E. So I could set MAX_MEM to 704. Then if I add a jumper to the motherboard (e2: 2-3) sw 4 closed, sw 3 open, it maps 640K plus Segs A, B, D, & E. Then I could set MAX_MEM=736. Supposedly, the CGA can still use the upper half of segment B, even though the GAL has all of B mapped to ram. But I have yet to test this, so I would most likely set it to map segments A,D and E.
                  Last edited by ibmapc; May 2, 2012, 06:48 PM.


                    I have installed pcxtbios 3.1 on my IBM 5155 4.77Mh 640k, it work fine, but when i boot it say Game port found at 201h, i haven't Game port
                    I have only CGA card original, FDC controller original IBM for floppy 360k and Parallel card original.
                    Any idea ?


                      Something else must be responding to port 201h reads. Unfortunately I do not have a 5155 so I can't troubleshoot further. You can prevent the game port from showing detected by removing line 802 (directly after @@found_game).