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

8 bit IDE (XTA) Replacement Project

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

    #76
    Honestly all this weirdness and kneecapping limitations seems to make a pretty ironclad case that the one practical application for an XTA replacement drive is machines that are stuck with XTA ports on the motherboard and no option to use an XTIDE or XT-CF with none of these problems, but I guess it’s useful to at least get all this documentation reconstructed.
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs Also: Blogspot

    Comment


      #77
      Originally posted by Eudimorphodon View Post
      Honestly all this weirdness and kneecapping limitations seems to make a pretty ironclad case that the one practical application for an XTA replacement drive is machines that are stuck with XTA ports on the motherboard and no option to use an XTIDE or XT-CF with none of these problems, but I guess it’s useful to at least get all this documentation reconstructed.
      LOL. What, you don't want a hard to configure device that costs more than an XT-IDE lite, only gives you 40MB of storage and you can't easily pop the card in and out of the rear slot? But then you wouldn't need to also buy a controller card that costs as much as an XT-IDE lite.

      Maybe I should have done a RAM + XT-IDE upgrade for the 5140 instead.

      Comment


        #78
        Originally posted by JayesonLS View Post
        Maybe I should have done a RAM + XT-IDE upgrade for the 5140 instead.
        Heh. I actually have that in my project queue, currently stalled for several reasons including the complete and utter unobtanium status of the rear bus connector. (The workaround I started going down is sacrificing the guts of a parallel/serial module instead, that’s “only” going to require laying out a card edge with completely proprietary spacing and severe space limitations.) Trust me, that thing is a heaping bucket of pure hurt. IBM actively went to great lengths to make that critter difficult for third party expansion. Even the internal RAM cards have a proprietary demux bus decoder on them. Every card does.
        My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs Also: Blogspot

        Comment


          #79
          Originally posted by Eudimorphodon View Post

          Heh. I actually have that in my project queue, currently stalled for several reasons including the complete and utter unobtanium status of the rear bus connector. (The workaround I started going down is sacrificing the guts of a parallel/serial module instead, that’s “only” going to require laying out a card edge with completely proprietary spacing and severe space limitations.) Trust me, that thing is a heaping bucket of pure hurt. IBM actively went to great lengths to make that critter difficult for third party expansion. Even the internal RAM cards have a proprietary demux bus decoder on them. Every card does.
          I was thinking a double-size RAM card that added up to 512 of RAM, with 128K of that potentially being UMB, and JRide style memory mapped XT-IDE. You can't get the CF card out easily, but if you have the serial adapter (I do, so I guess I am biased), you can transfer files over that pretty easily. I am wondering now if maybe all the needed address lines are not available.

          Comment


            #80
            Getting back on topic, I think I will try to finish out the XTA interface card since I have put some thought into it. Plan is to make it configurable as either an ST05X, or a WDXT-150 card. I am going to use a pair of GAL16V8s for all of the glue logic. Keeps the part count down, and the BOM short. Also the least expensive option as far as purchasing parts go - Atmel's 16V8's are about 1.5x the cost of a typical LS logic chip and in this case, do a lot more work. The two 16v8's have a little logic to spare if future feature needs come up.

            XTA decode.PNG

            Comment


              #81
              Originally posted by JayesonLS View Post
              I was thinking a double-size RAM card that added up to 512 of RAM, with 128K of that potentially being UMB, and JRide style memory mapped XT-IDE. You can't get the CF card out easily, but if you have the serial adapter (I do, so I guess I am biased), you can transfer files over that pretty easily. I am wondering now if maybe all the needed address lines are not available.
              They’re (effectively) not, the RAM socket is hard decoded to under-640k area and the daisy-chained cards use a weird system that hard codes them to 128k each, IBM’s own 256k cards use a workaround to effectively look like two cards. You would have to tap signals on the motherboard proper and somehow trick the decoder, which is an ASIC, to sneak more RAM or a peripheral through that door. (It was one of many ideas I floated myself.)
              My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs Also: Blogspot

              Comment


                #82
                Still lots of work to do but making some progress on this ST & WD all-in-one XTA interface card.

                image_63468.png

                Comment


                  #83
                  Originally posted by JayesonLS View Post
                  Does anyone have an ST05X card with the resistor(s) populated on the area I have highlighted below? It is not populated on my card and would like to know the resistor value. The HD activity LEDs are driven directly by the hard drive and the current capability is not documented. I'd like to keep things simple and just use Seagate's original value.
                  My ST05X is a different design which has unused circuit traces for a floppy drive controller. The activity LED pin header is not installed, and neither are the resistors for it.


                  Comment


                    #84
                    i have two of those Double connector cards also. Mine has a tiny smd resistor in the upper left corner. 11.jpg 12.jpg

                    I have to check to see if it is the same like yours.

                    Also have those AT/XT Seagate drives. Guessing having 3 of them.. I have enough stuff laying around.. Mostly its hard to find anything here..
                    Last edited by Robin4; September 12, 2021, 02:11 PM.
                    THE BIOS MASTER

                    Comment


                      #85
                      Originally posted by Robin4 View Post
                      Mine has a tiny smd resistor in the upper left corner.
                      Thanks, that is just what I was after. 220 ohm. I have the same card as VWestlife. It came out of a Tandy hard card assembly and I guess they figured that Tandy's don't have unused HD LEDs, so why confuse people with a header for one.

                      Comment


                        #86
                        I am rather curious to know of either of the ST05X or WDXT-150 supports 2 hard drives.

                        From looking at the disassembly of the ST05X BIOS, it seems to support a second drive. Except as best I can tell it will never set the drive 1 (second drive) parameter table. It looks like this would not be set even if the case of a non-ST05X drive being set up first. I assume this parameter table is needed for the drive to work. The BIOS does set the number of drives in the BIOS to 2 so not sure what DOS does with that.

                        The WD BIOS, admittedly from a Compuadd 810 and not a WDXT-150, does not appear to be configured for two drives via one BIOS. Interesting since the WDXT-150 has an unpopulated second header. It is possible that the BIOS I have is not what is on a WDXT-150 however the rest of the handling of options in the BIOS is consistent with the WDXT-150 (BIOS and port addresses). I think the BIOS might be able to handle two drives if two WDXT-150 were installed, each with different BIOS address, port address and IRQ. The different IRQ seems to be necessary as the BIOS fully takes over the IRQ handler.

                        Comment


                          #87
                          The layout for the XTA controller turned out to be fairly easy. I'll write the GAL logic before I order boards since that usually turns up a problem or two. Probably tweak a few things before it goes out out also.

                          XTA-Interface-Top-Bottom.png

                          Comment


                            #88
                            Any hope for interleaves lower than 3:1 or is that simply as fast as 8-bit XTA can go?

                            Comment


                              #89
                              Originally posted by vwestlife View Post
                              Any hope for interleaves lower than 3:1 or is that simply as fast as 8-bit XTA can go?
                              If you're talking about the host adapter there's not a thing it can do to influence that, the controller is on the drives. This passes through all data and commands unmodified, it just decodes the IO/memory address it responds to and (apparently) slightly massages a couple control lines.

                              Theoretically a flash-based XTA replacement *drive* should be able to run at whatever the theoretically achievable DMA speed is, or about the same speed as a DMA XTIDE card, probably whichever is lower.
                              My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs Also: Blogspot

                              Comment


                                #90
                                But the format utility, that sets the interleave, is in the BIOS on the host adapter, right?

                                Has anyone ran spinrite with one of these drives? Does it talk about the interleave and being able to change it?

                                Comment

                                Working...
                                X