Announcement

Collapse

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

Original-IBM-5150 or IBM-Clone Memory Experimentation Thread

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    #61
    Sorry about the delay. Looking over my pin-routing, The RAS and CAS are fed to the memory ICs by a 157, a LS08 (AND gate), and a 138.

    I'd have to check whether that matches up with any schematic I've looked over before. (If this feeds through the same types of logic gates present in those ICs)

    Comment


      #62
      Are you actually writing down a schematic for your machine as you're doing this? Because you really need a complete schematic to determine under what circumstances (IE, state of the address lines) which RAS/CAS pair is active. (And also for what address ranges that '245 on the RAM data lines is enabled.) Open up the 5150 and 5160 service manuals and look at sheet 3 of the schematics for both of those machines: What you need to know is what is *immediately upstream* of the '138s. (There should be two, one that directly supplies the CAS lines and the other that supplies RAS through the '08.) The input and enable lines (1,2,3 and 4,5,6) will connect to some combination of address lines and an address decoder. That address decoder is what you need to understand. Full stop. There are many things it could be, the 5150's schematic is the "simple" version and the 5160's is a fully programmable one. Diagram everything, accurately. There is no particular reason the Sanyo's address decoder should match either IBM machine's particularly closely, there are *many* ways this to skin this cat and you need to understand what Sanyo actually did.
      My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs Also: Blogspot

      Comment


        #63
        Originally posted by Eudimorphodon View Post
        Are you actually writing down a schematic for your machine as you're doing this? Because you really need a complete schematic to determine under what circumstances (IE, state of the address lines) which RAS/CAS pair is active. (And also for what address ranges that '245 on the RAM data lines is enabled.)
        Not a schematic (yet), just a routing from a pin-listing of one chip to the other, with their corresponding silkscreen numbers (the 8088 and 8087 are off on the right) Sorry I can't make it any clearer:

        Sanyo Pin Routing small.png
        Originally posted by Eudimorphodon View Post
        Open up the 5150 and 5160 service manuals and look at sheet 3 of the schematics for both of those machines: What you need to know is what is *immediately upstream* of the '138s. (There should be two, one that directly supplies the CAS lines and the other that supplies RAS through the '08.) The input and enable lines (1,2,3 and 4,5,6) will connect to some combination of address lines and an address decoder. That address decoder is what you need to understand. Full stop. There are many things it could be, the 5150's schematic is the "simple" version and the 5160's is a fully programmable one. Diagram everything, accurately. There is no particular reason the Sanyo's address decoder should match either IBM machine's particularly closely, there are *many* ways this to skin this cat and you need to understand what Sanyo actually did.
        And yes, I've already realized that what Sanyo has done doesn't match up perfectly in any way in places (i.e. It's mostly the same gates and same routing, but instead you're routing an input through the same gate in a different logic chip).

        Comment

        Working...
        X