Announcement

Collapse

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

Building my own PDP computer

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

    Building my own PDP computer

    I'm a fan of computers ever since I was a child and love the look of classic computers from the golden age of processors and with that said I'll be stepping up and constructing my own pdp computer. If anyone here has done this please tell me how your experience was with it.

    #2
    That sounds like a daunting task, will it be a visual thing only or do you plan to make it compatible with the PDP model you are remaking? (also, which model are you going for?)

    You might want to look at: http://www.sparetimegizmos.com/Hardware/SBC6120-2.htm
    Looking for: anything from SGI or DEC/digital
    Pictures of my collection: www.pdp8.se

    Comment


      #3
      Hi! My hat is off to you for taking on a seriously challenging project! Please keep us posted.

      You might want to consider a Heathkit H-11 either as an alternative or a starting point for design. DEC PDP is not my specialty for sure but it looks like a solid platform.

      Thanks and good luck! Have a nice day!

      Andrew Lynch

      Comment


        #4
        Vintman,

        Do you mean designing your own computer, or building one from parts? If the latter, the SBC6120 mentioned above is good if you want to explore the pdp-8 family. Alternatively, if you want to explore the pdp-11 family, you can buy all the bits and pieces to build a q-bus (look it up) pdp-11 off ebay one $10 board at a time. A number of us here have done both.

        What is your skill level with electronics? Are you a decent technician?

        Lou

        Comment


          #5
          The term "PDP" is pretty broad. The PDP-11 range alone spans about 20 years and encompasses many very different machines. Which one you choose to base your project on will likely depend on complexity, so I'd imagine you'd be looking at the earlier end of the spectrum. That said, if you're going for an authentic replica, early systems are very complex due to the number of discrete components used while later systems benefit from increasing levels of integration. Other factors to consider would be your own experience in similar projects and what you intend to do with the finished product.

          There are many different ways to build a PDP-like machine, for example:
          • A control panel hooked up to a simulator/emulator running on a small PC or SBC. There are at least a couple of projects on the web which use this approach with original PDP-11/70 front panels. Others have built their own (sometimes very accurate) replicas of various models' control panels.
          • Implement a PDP system in programmable logic, like an FPGA. I know there are existing designs for PDP-8 processors although I'm not sure if these are available for general use. Again, you could hook this up to some kind of control panel, or just leave it at a serial console.
          • Build a system based on an existing LSI-11 chip (basically a PDP-11 processor on one big chip). You may be limited to a serial console here as IIRC not all signals required for a full front panel are accessible from outside the chip.
          • Build a complete processor out of discrete parts. This may sound complicated, but the schematics for most PDP-11 models are available for reference. The PDP-11/34 is, for example, "only" two big boards of chips.
          Steve Maddison
          Digital, Sinclair, Commodore, homebrew Z80 and other stuff...

          Comment


            #6
            Well, building a PDP-14 should be pretty easy, although not very satisfying (note the complete lack of arithmetic instructions).

            What methods do you want to employ? As someone said, there's a kit using the SBC6120 for the 12-bit PDP-8 (whose CPU might even fit in a large CPLD). Do you want to build a PDP-1 from discrete logic and core memory (good luck!)? You can easily fit a PDP-11 architecture in an FPGA--I believe that at least one such implementation already exists.
            Reach me: vcfblackhole _at_ protonmail dot com.

            Comment


              #7
              Thank you lynchaj it's a grueling adventure but i can see the light at the end of the tunnel and I'm slowly making my through it, thanks for the support :^)

              Comment


                #8
                I'm going too throw my hat into the ring and try and make it compatible, I plan it being a pdp-11 my fav in the series lol, wish me luck.

                Comment


                  #9
                  I'm going too start my journey this weekend into the construction of my pdp project, i'm extremely tired going over notes and design plans and dear god the memory.....well gotta hit the hay, i'll keep you informed and might even video document thisjourney and post it on youtube, will keep you guys posted, peace :^)

                  Comment


                    #10
                    The PDP-11 is nice, not overly complex but still a big bite to chew on. Keep us posted
                    Looking for: anything from SGI or DEC/digital
                    Pictures of my collection: www.pdp8.se

                    Comment


                      #11
                      My dream is slowly coming along, just working on some final reviews in the design and going over my parts too make sure I got everything. It's a long battle but I know I'm going too make it, peace

                      Comment


                        #12
                        So which approach did you decide on in the end? Care to fill us in on any of the major design features?
                        Steve Maddison
                        Digital, Sinclair, Commodore, homebrew Z80 and other stuff...

                        Comment


                          #13
                          Please do, I'm curious as well.
                          Looking for: anything from SGI or DEC/digital
                          Pictures of my collection: www.pdp8.se

                          Comment

                          Working...
                          X