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Format with write protect on...

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    #61
    Ok, I found the DMA controller ... on the add-on card. Geez, shows how much I know about Tandy's, because I figured that out only after I looked it up Anyway, pulling the 8237 results in a dead computer that only emits a steady beep. Can't format a floppy like that haha.

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      #62
      Well, I"m now worse off than when I started (as if owning a Tandy 1000 could get any worse)... the machine won't boot on 128k, and I'm getting a memory error with the card installed (and no boot). Bummer. Now I'm off to figure out how to fix a Tandy 1000 ram error.

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        #63
        Hey, good news .... and you are correct! I now have the same formatting behavior without DMA. Interesting behavior! (I was finally able to boot in 128k using DOS 3.1)

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          #64
          >I now have the same formatting behavior without DMA. Interesting behavior! (I was finally able to boot in 128k using DOS 3.1)

          Good job Chris!!!! I was going to say you can't boot DOS 6.22 on 128K for certain. I tried and it fails. My test version for that has been 3.30.

          So it goes ahead and acts like it is formatting the disk, but fails at the end right? But, all the file data is still there, right?

          So it is a bug in the non-DMA routines.

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            #65
            Originally posted by alank2 View Post
            >I now have the same formatting behavior without DMA. Interesting behavior! (I was finally able to boot in 128k using DOS 3.1)

            Good job Chris!!!! I was going to say you can't boot DOS 6.22 on 128K for certain. I tried and it fails. My test version for that has been 3.30.

            So it goes ahead and acts like it is formatting the disk, but fails at the end right? But, all the file data is still there, right?

            So it is a bug in the non-DMA routines.
            Yes, it is acting exactly like you describe. It goes through the format, but then fails at the end. Disk was write protected. I'd say too that you stumbled on something interesting and DMA related for sure!

            Also I got the RAM error fixed and the machine is back together now, but I can easily do more testing if there's anything else that should be confirmed.

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              #66
              Originally posted by chris_nh View Post
              Yes, it is acting exactly like you describe. It goes through the format, but then fails at the end. Disk was write protected. I'd say too that you stumbled on something interesting and DMA related for sure!
              Also I got the RAM error fixed and the machine is back together now, but I can easily do more testing if there's anything else that should be confirmed.
              Thank you for doing the testing to confirm it! Good job sir!!

              The question now perhaps is - for the other Tandy 1000's that do not have a DMA controller - which ones have the bug? Presumably the regular 1000 does.

              I may when I get time try to compare the DMA format track to the non-DMA format track in the IDA that was posted above if I get a chance.

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                #67
                Originally posted by chris_nh View Post
                Ok, I found the DMA controller ... on the add-on card. Geez, shows how much I know about Tandy's, because I figured that out only after I looked it up Anyway, pulling the 8237 results in a dead computer that only emits a steady beep. Can't format a floppy like that haha.
                Errors would be expected behavior if you pulled the DMA controller off an original memory card; no DMA chip means no RAM refresh. (Modern cards that use SRAM are fine without it.)

                So, yeah, that’s an interesting find. I can try again on my 1000HX with other versions of DOS, I guess, maybe PC DOS 2000 magically behaves differently, but it could well be some kind of bug fix. Probably should also try the EX if I really want to be complete.
                My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs Also: Blogspot

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                  #68
                  I hereby name it the "Tandy 1000 non-DMA write protected format BIOS bug."!

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                    #69
                    I'm finding this thread extremely interesting as I've been a 1000SX owner since late 1986. But here's the thing, why would you want to format a disk with write protection on in the first place, unless it was just a mistaken event? Here I go over simplifying again as I would just let a sleeping dog lie.
                    Surely not everyone was Kung-fu fighting

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                      #70
                      Not "want" to do it, but it's nice to be notified if you accidentally left write disabled.

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                        #71
                        Originally posted by Chuck(G) View Post
                        Not "want" to do it, but it's nice to be notified if you accidentally left write disabled.
                        See, I'm confused and it doesn't take much these days. I thought this was about attempting to format with the write protection on.
                        Surely not everyone was Kung-fu fighting

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                          #72
                          "write disabled" = "write protected"

                          You want to know about that--otherwise if you think you have a freshly formatted floppy and it's not, it could be disrupting to your life.

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                            #73
                            Originally posted by Chuck(G) View Post
                            "write disabled" = "write protected"

                            You want to know about that--otherwise if you think you have a freshly formatted floppy and it's not, it could be disrupting to your life.
                            Okay, then you're talking about "write disabled" as a fault as it's not selectable.
                            Surely not everyone was Kung-fu fighting

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                              #74
                              The whole point of write protection is to keep a disk from being changed/overwritten in the first place, people make mistakes. Thankfully the bug does not allow the disks data to change. It should fail immediately, but doesn't. That is the bug. Clearly the non-dma BIOS function doesn't check the result of the format operation somehow.

                              Comment


                                #75
                                Originally posted by alank2 View Post
                                The whole point of write protection is to keep a disk from being changed/overwritten in the first place, people make mistakes. Thankfully the bug does not allow the disks data to change. It should fail immediately, but doesn't. That is the bug. Clearly the non-dma BIOS function doesn't check the result of the format operation somehow.
                                I'm a little slow on this but I'm starting to catch on. I've been running my 1000SX for over 35 years and just never seen or heard of anything like what you're going through. Seems a bit odd to me.
                                Surely not everyone was Kung-fu fighting

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