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

I wish to create a new DMA/RAM expansion card for the Tandy 1000 line.

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

    Originally posted by Eudimorphodon View Post
    Yeah. I tried that configuration on the road to ripping it down to just the RAM chip and nothing else. (Also tried with just the '00 and RAM but the buffer bypassed.)

    I'm going to have another crack at it after taking a break. Thinking of setting up a simple breadboard circuit I can plug into the address lines and verify that a given combination results in the expected selects; I quadruple checked it before sending off the board but... is what it is. I wish I had a way at hand to test the RAM chips.
    And the quick and dirty didn't work? Would you mind uploading your KiCad project somewhere? A fresh pair of eyes might help.

    If you plug the chip straight up to the bus with A19 as the enable, you should be able to at least run CheckIt 3 and do a memory test to find out if the chip is good.
    My vintage systems: Tandy 1000 HX, Tandy 1000 RSX, Tandy 1100FD, Tandy 64K CoCo 2, Commodore VIC-20, Hyundai Super16TE (XT clone), and some random Pentium in a Hewitt Rand chassis...

    Some people keep a classic car in their garage. Some people keep vintage computers. The latter hobby is cheaper, and is less likely to lead to a fatal accident.

    Comment


      Originally posted by blackepyon View Post
      If you plug the chip straight up to the bus with A19 as the enable, you should be able to at least run CheckIt 3 and do a memory test to find out if the chip is good.
      That's the thing, I effectively tried that configuration through the board and it still produced POST-halting errors. (Decode logic pulled and jumpers placed between the bus data lines and the inside side of the buffer socket, a17 bridged around the inversion to allow D000h, and A19 bridged to the RAM chip enable.) Unless there's something like intermittent connectivity through the patch jumpers happening that should have worked? I've continuity tested everything, and the RAM chip is receiving 5v.

      I'll have to buy some more patch wires to go straight to the bus socket skipping the board. I'll see if I can but the situation is perplexing.
      My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs Also: Blogspot

      Comment


        Originally posted by eeguru View Post
        Also here are my dimensions for the PLUS cards I've built (XT-IDE, HardMPU, Memory, and NE2000) so you can cross-check your footprint:
        [ATTACH=CONFIG]54073[/ATTACH]

        Edit: Just realized the forum decimates the resolution a great deal.

        Re-hosted here
        I've noticed that the forum likes to "decimate" *.png files. If you upload them as *.jpg, it doesn't have a problem.

        By the way, I noticed you got a half inch between the sets of 3 screw holes on the back plate. How'd you get that? As far as I can figure (without a modem or serial PLUS card), they should be about half that, to allow for installation in the first slot in the absence of the memory card. Or do I have that wrong?
        Last edited by blackepyon; June 29, 2019, 08:07 PM.
        My vintage systems: Tandy 1000 HX, Tandy 1000 RSX, Tandy 1100FD, Tandy 64K CoCo 2, Commodore VIC-20, Hyundai Super16TE (XT clone), and some random Pentium in a Hewitt Rand chassis...

        Some people keep a classic car in their garage. Some people keep vintage computers. The latter hobby is cheaper, and is less likely to lead to a fatal accident.

        Comment


          Btw I got a batch of DS1315-5+ chips the other day and tested them in my SmartWatch+ board - As I thought, they are a perfect drop-in replacement for the DS1216's.
          My Retro Collection:
          CBM: C64, Amiga 500 x2, 600 & 1200
          Apple's: IIc, Mac SE, LCII, LC630 & Power Mac G3/233 Desktop
          PC's: K6-III+ 500 System + Roland MT-32 & Tandy 1000 EX 640kb, 3.5" FDD, CF-IDE 4GB HDD
          Visit my Tindie store for Tandy 1000 Adapters for EX, HX, SX, SL, TX & TL etc

          Comment


            Originally posted by dJOS View Post
            Btw I got a batch of DS1315-5+ chips the other day and tested them in my SmartWatch+ board - As I thought, they are a perfect drop-in replacement for the DS1216's.
            Do they need a different version of the SmartWatch software or they just work as-is?
            My vintage systems: Tandy 1000 HX, Tandy 1000 RSX, Tandy 1100FD, Tandy 64K CoCo 2, Commodore VIC-20, Hyundai Super16TE (XT clone), and some random Pentium in a Hewitt Rand chassis...

            Some people keep a classic car in their garage. Some people keep vintage computers. The latter hobby is cheaper, and is less likely to lead to a fatal accident.

            Comment


              Originally posted by blackepyon View Post
              Do they need a different version of the SmartWatch software or they just work as-is?
              Nope, they just work with no modifications at all.

              After I read this (below) I was pretty confident that would be the case.

              https://www.maximintegrated.com/en/a...ndex.mvp/id/52
              My Retro Collection:
              CBM: C64, Amiga 500 x2, 600 & 1200
              Apple's: IIc, Mac SE, LCII, LC630 & Power Mac G3/233 Desktop
              PC's: K6-III+ 500 System + Roland MT-32 & Tandy 1000 EX 640kb, 3.5" FDD, CF-IDE 4GB HDD
              Visit my Tindie store for Tandy 1000 Adapters for EX, HX, SX, SL, TX & TL etc

              Comment


                Originally posted by dJOS View Post
                Nope, they just work with no modifications at all.

                After I read this (below) I was pretty confident that would be the case.

                https://www.maximintegrated.com/en/a...ndex.mvp/id/52
                Sweet!
                And Digi-Key actually keeps these in stock! Bonus!
                Not exactly cheap for a 16-pin DIP ($23 CDN) but they're new, and available!
                Adding some of that to my next order...
                My vintage systems: Tandy 1000 HX, Tandy 1000 RSX, Tandy 1100FD, Tandy 64K CoCo 2, Commodore VIC-20, Hyundai Super16TE (XT clone), and some random Pentium in a Hewitt Rand chassis...

                Some people keep a classic car in their garage. Some people keep vintage computers. The latter hobby is cheaper, and is less likely to lead to a fatal accident.

                Comment


                  Originally posted by blackepyon View Post
                  By the way, I noticed you got a half inch between the sets of 3 screw holes on the back plate. How'd you get that? As far as I can figure (without a modem or serial PLUS card), they should be about half that, to allow for installation in the first slot in the absence of the memory card. Or do I have that wrong?
                  I'm not sure what you mean. My dimensions are 1/2 inch difference in width from left hole to right hole. That's 1/4" from adjacent hole to hole.
                  "Good engineers keep thick authoritative books on their shelf. Not for their own reference, but to throw at people who ask stupid questions; hoping a small fragment of knowledge will osmotically transfer with each cranial impact." - Me

                  Comment


                    Originally posted by eeguru View Post
                    I'm not sure what you mean. My dimensions are 1/2 inch difference in width from left hole to right hole. That's 1/4" from adjacent hole to hole.
                    Oh! Never mind, I read that wrong.
                    My vintage systems: Tandy 1000 HX, Tandy 1000 RSX, Tandy 1100FD, Tandy 64K CoCo 2, Commodore VIC-20, Hyundai Super16TE (XT clone), and some random Pentium in a Hewitt Rand chassis...

                    Some people keep a classic car in their garage. Some people keep vintage computers. The latter hobby is cheaper, and is less likely to lead to a fatal accident.

                    Comment


                      Originally posted by blackepyon View Post
                      Sweet!
                      And Digi-Key actually keeps these in stock! Bonus!
                      Not exactly cheap for a 16-pin DIP ($23 CDN) but they're new, and available!
                      Adding some of that to my next order...
                      I have a few of those supposedly sitting somewhere in Ohio last I checked (which means they should get here soon) that only cost around $6 a chip, but since I ordered them from China I'm girding myself for the real possibility that they're going to be garbage. It's good to have confirmation that they are indeed software compatible with the older chip, though.

                      I'm still at a loss here. I've retraced everything (including checking the one thing I hadn't absolutely verified, which is that something plugged into the female connector on the bottom of the board had good connectivity; it's fine) and my conclusion is that even if my decoding logic was somehow completely b***s-up wrong the jumpering I did to dumb it down should have worked if the RAM was good. My best guess how to proceed at this point is to order another RAM chip from a reputable dealer (Digi-Key, Mouser, whatever) and pray I really did get scr3wed. (I will be hitting the board with the logic probe/scope to make sure the enables are working as expected as well, but I'm skeptical I'm going to find a smoking gun.)

                      Re: hole spacing, yes, I derived quarter-inch spacing from my scaled version of the PCB art for the Plus RAM card in the Tandy manual (I didn't even think to measure the hole spacing on the rear bezel of the modem card, duh), and it seems to jive with reality:

                      tandyholes.jpg

                      I did test fit it and the Modem card will seat properly over my board (the large line filter just *barely* clears the calendar battery holder) on the "inside" connector, and it looks like if I stick the stacking headers I bought on the outside connector it'd line it up correctly for the top slot position.

                      Just need to make the bloody thing work first.
                      My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs Also: Blogspot

                      Comment


                        Originally posted by blackepyon View Post
                        Sweet!
                        And Digi-Key actually keeps these in stock! Bonus!
                        Not exactly cheap for a 16-pin DIP ($23 CDN) but they're new, and available!
                        Adding some of that to my next order...
                        That's where I got mine from - I'm going to try another source I found that was under $3 per chip, I'll report back if they are any good.
                        My Retro Collection:
                        CBM: C64, Amiga 500 x2, 600 & 1200
                        Apple's: IIc, Mac SE, LCII, LC630 & Power Mac G3/233 Desktop
                        PC's: K6-III+ 500 System + Roland MT-32 & Tandy 1000 EX 640kb, 3.5" FDD, CF-IDE 4GB HDD
                        Visit my Tindie store for Tandy 1000 Adapters for EX, HX, SX, SL, TX & TL etc

                        Comment


                          Originally posted by Eudimorphodon View Post
                          I'm still at a loss here. I've retraced everything (including checking the one thing I hadn't absolutely verified, which is that something plugged into the female connector on the bottom of the board had good connectivity; it's fine) and my conclusion is that even if my decoding logic was somehow completely b***s-up wrong the jumpering I did to dumb it down should have worked if the RAM was good. My best guess how to proceed at this point is to order another RAM chip from a reputable dealer (Digi-Key, Mouser, whatever) and pray I really did get scr3wed. (I will be hitting the board with the logic probe/scope to make sure the enables are working as expected as well, but I'm skeptical I'm going to find a smoking gun.)
                          Just need to make the bloody thing work first.
                          Good to know that the holes line up as I expected.

                          And hey, like I said, I can go over your schematics with a fresh set of eyes if you can upload the KiCad project somewhere. I already got what I need, which is the 3-chip solution we worked out (that way I've got room for the DMA logic once I get that figured out). I'd be happy to help out in any way I can.
                          My vintage systems: Tandy 1000 HX, Tandy 1000 RSX, Tandy 1100FD, Tandy 64K CoCo 2, Commodore VIC-20, Hyundai Super16TE (XT clone), and some random Pentium in a Hewitt Rand chassis...

                          Some people keep a classic car in their garage. Some people keep vintage computers. The latter hobby is cheaper, and is less likely to lead to a fatal accident.

                          Comment


                            Originally posted by blackepyon View Post
                            And hey, like I said, I can go over your schematics with a fresh set of eyes if you can upload the KiCad project somewhere. I already got what I need, which is the 3-chip solution we worked out (that way I've got room for the DMA logic once I get that figured out). I'd be happy to help out in any way I can.
                            It's been a while, so I figured I should probably update that I haven't given up or anything. The last couple weeks suddenly got very busy, which might be the case for a few more.

                            I'll see what I can do to get the schematics posted somewhere in something like a usable form, because I'm still at a dead end. (A screenshot stuck on the forum here as a JPEG will of course suffer massive degradation.) The only work I've been able to do for the last week is start on recreating my decoding circuitry on a protoboard to quadruple check the logic does what I expect it to do with given address line inputs. About half done with that, so far everything checks out.

                            Been fighting the urge to wire one of the RAM chips up to my Commodore PET to interactively check it. The PET presents all the necessary signals on a couple header connectors on the motherboard and has pre-defined chip select signals already on the connector so it wouldn't require any decoding. I'd only be able to test 4k of it at once but that would be enough to sanity check if I was given completely dead ICs...
                            My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs Also: Blogspot

                            Comment


                              Originally posted by Eudimorphodon View Post
                              It's been a while, so I figured I should probably update that I haven't given up or anything. The last couple weeks suddenly got very busy, which might be the case for a few more.

                              I'll see what I can do to get the schematics posted somewhere in something like a usable form, because I'm still at a dead end. (A screenshot stuck on the forum here as a JPEG will of course suffer massive degradation.) The only work I've been able to do for the last week is start on recreating my decoding circuitry on a protoboard to quadruple check the logic does what I expect it to do with given address line inputs. About half done with that, so far everything checks out.
                              Yeah, been busy on my end too. Got a mountain of paperwork I've been lagging behind on for my "day job" (small landscaping business) that I need to get back to.

                              Doesn't need to be pretty. Just drop the KiCad project folder onto Mediafire or somewhere and drop me a link. I can prototype it on a breadboard on my end to make sure that there's not some hidden difference we might have missed between the EX and HX that might be interfering (I DOUBT that would be the case, but just to make sure).
                              My vintage systems: Tandy 1000 HX, Tandy 1000 RSX, Tandy 1100FD, Tandy 64K CoCo 2, Commodore VIC-20, Hyundai Super16TE (XT clone), and some random Pentium in a Hewitt Rand chassis...

                              Some people keep a classic car in their garage. Some people keep vintage computers. The latter hobby is cheaper, and is less likely to lead to a fatal accident.

                              Comment


                                Wow, this is really cool! I’ve got an EX that needs more memory, and am very interested in this. I wonder what the reason of not building a DMA controller into the machine was?
                                Last edited by compaqportableplus; July 14, 2019, 05:37 AM. Reason: Typo
                                Compaq - It simply works better

                                Comment

                                Working...
                                X