Brian, you are absolutely correct.  You sent me everything I possibly needed to 
understand how this should work and I managed to ignore some of it.

I really, really appreciate all your help.

I’m just pumped that both DVI’s work when for a while I thought neither did.

I will check the disk to see if has the 200 files on it, although I don’t have 
plans to get a T200.  I had one a few years ago and sold it.

Thanks again!

Randy
> On Feb 19, 2018, at 2:42 AM, Brian White <bw.al...@gmail.com> wrote:
> 
> The manual, which is on-line btw, does mention somewhere in there that the 
> first step loads software from the disk to the dvi. Then the 2nd step loads 
> from the dvi to the M100. It also shows the backup procedure and all kinds of 
> other stuff.
> 
> Also, 3 observable things do happen when the M100 is loaded successfully, 
> it's just that none of them obviously look like "Everything worked, we're 
> ready."
> 
> 1) The M100 menu screen blanks and redraws.
> 
> 2) The free memory display on the M100 menu reduces by about 5K.
> 
> 3) The TV screen clears. The the Microsoft/Tandy boilerplate goes away 
> leaving only a cursor.
> 
> I should have thought to ask if you saw these in the first place. I did say 
> "nothing happens" but that still isn't good enough because how could you know 
> what counts as "something" when it's just things like that?
> 
> Though, I believe this is all in the video I posted. Did I ever post a link 
> here? I don't remember, maybe I only posted that to facebook...
> https://youtu.be/Mt6AmyLKkXQ <https://youtu.be/Mt6AmyLKkXQ>
> Not wait, I did post it here because didn't you point out that it looked like 
> I was using the serial port? So you saw the entire boot process. So you have 
> no excuse after all :)
> 
> The service manual is also on-line which describes even more about how the 
> dvi works.
> 
> http://www.classiccmp.org/cini/pdf/Tandy/Disk%20Video%20Interface%20Manual.pdf
>  
> <http://www.classiccmp.org/cini/pdf/Tandy/Disk%20Video%20Interface%20Manual.pdf>
> 
> http://www.classiccmp.org/cini/pdf/Tandy/Disk%20Video%20Interface%20Service%20Manual.pdf
>  
> <http://www.classiccmp.org/cini/pdf/Tandy/Disk%20Video%20Interface%20Service%20Manual.pdf>
> 
> It went similar with me. I thought I had 2 dead DVIs and 3 bad original 
> system disks, Then it turned out I had 2 good dvis, 3 good original system 
> disks, and merely one bad drive in one dvi. But I also had an unconfirmed 
> cable I made myself too, not one anyone else claimed was correct and tested. 
> I had no reason to believe I had it wired right. Now after finding some 360K 
> drives on ebay and finding just enough documentation on-line to set the 
> jumpers right, I have 2 fully working dvis, with 2 drives each no less.
> 
> Now the last thing is, does your system disk contain files with 200 in the 
> name, like FMT200 and BAK200 ? And if not, do you have or plan to have a 200? 
> There are two versions of the system disk. One is for 100 & 102 only, the 
> other is for 100, 102, & 200. If you don't have the 100/200 system disk I can 
> make a copy.
> 
> -- 
> bkw
> 
> On Feb 18, 2018 6:31 PM, "Randall Kindig" <randall.kin...@gmail.com 
> <mailto:randall.kin...@gmail.com>> wrote:
> Wow, I hooked up the original DVI box now that I know how all this works, and 
> since I verified the cable/M100/boot disk combination that works.
> 
> Guess what, it works too!!
> 
> I think what was throwing me was that when you reset the M100, the disk light 
> on the DVI doesn’t even come on most times.  You just hear a very brief disk 
> noise from it, a second or two, and that must be all it takes to load the 
> DISK BASIC.  You then go into BASIC on the M100, type SCREEN 1,1 and voila!
> 
> I had originally assumed the disk drive light would come on and that it would 
> take several seconds to load DISK BASIC, so I was looking for that behavior.
> 
> I now have a preponderance of riches.  Two working DVI boxes.  I’ll probably 
> sell a fully tested system on eBay with cable, boot disk, M100, DVI and 
> recover some of the funds I spent on all this.
> 
> Thanks to everyone who helped with this. Especially you, Brian.  I owe you 
> that beer :)
> 
> Randy
> 
> 
> 
>> On Feb 18, 2018, at 5:45 PM, Randall Kindig <randall.kin...@gmail.com 
>> <mailto:randall.kin...@gmail.com>> wrote:
>> 
>> This worked perfectly, Brian!  I now have a backup system disk and both have 
>> the write-protect tab on them.
>> 
>> thanks!
>> 
>> By the way, the system is consistently booting now.  Just had to shake the 
>> dust off of it, I guess.
>> 
>> Still would like to see if I can get the other DVI box working.
>> 
>> Randy
>> 
>> 
>>> On Feb 17, 2018, at 10:24 PM, Brian White <bw.al...@gmail.com 
>>> <mailto:bw.al...@gmail.com>> wrote:
>>> 
>>> The easiest way is using the backup program on the system disk.
>>> 
>>> It's possible but I think it's probably more difficult with a modern pc. I 
>>> don't think just any modern floppy controller chip can do it, and you need 
>>> a 360K drive too, ideally, not the more common 1.2M drive. Then you also 
>>> need special formatter software, which I don't know how available that is 
>>> today, and don't know if it would work from dosbox or something. Might have 
>>> to make a freedos bootable usb stick just to run the disk writing util.
>>> 
>>> Steven Adolf has some notes on all that on club100 in the member uploads.
>>> 
>>> It's much simpler to just use "BACKUP.SNG" in your case right from the 
>>> system disk.
>>> 
>>> You would boot the dvi normally, then go into basic and:
>>> 
>>> RUN"0:FORMAT"
>>> 
>>> Then follow the prompts to remove the system disk and put in a disk to be 
>>> blanked and formatted.
>>> 
>>> Then put the system disk back in and:
>>> 
>>> NEW
>>> RUN"0:BACKUP.SNG"
>>> 
>>> Then follow the prompts to switch back and forth putting the new disk in, 
>>> then the system disk, then the new one again, etc, until it's over. Choose 
>>> All when it asks All or System.
>>> 
>>> I would definitely put tape over the write-protect notch on your one 
>>> remaining working system disk before any of this!
>>> 
>>> -- 
>>> bkw
>>> 
>>> On Feb 17, 2018 9:19 PM, "Randall Kindig" <randall.kin...@gmail.com 
>>> <mailto:randall.kin...@gmail.com>> wrote:
>>> I will check that, Brian.  Thanks for your help.
>>> 
>>> My other question is around the boot disk.  I was sent 2 boot disks with 
>>> the cable, but now only 1 seems to work.  I’m worried now only having one 
>>> working disk.
>>> 
>>> How do I back it up?  Is there a way to do that with the DVI?  Can I create 
>>> one in a different disk drive, like the drive in the TRS-80 Model 4P?
>>> 
>>> thanks
>>> 
>>> Randy
>>>> On Feb 17, 2018, at 9:15 PM, Brian White <bw.al...@gmail.com 
>>>> <mailto:bw.al...@gmail.com>> wrote:
>>>> 
>>>> This sounds consistent with Fugu's idea about old capacitors. It sounds 
>>>> like both dvi's are marginal, but one is slightly better than the other, 
>>>> and one of your M100's is slightly better than the other, and so with the 
>>>> two best ones combined, it just barely works, sometimes.
>>>> 
>>>> I would check that voltage as he described and I expanded.
>>>> 
>>>> On Feb 17, 2018 8:37 PM, "Randall Kindig" <randall.kin...@gmail.com 
>>>> <mailto:randall.kin...@gmail.com>> wrote:
>>>> SUCCESS!
>>>> 
>>>> Per John’s suggestion (and was thinking the same thing when he suggested 
>>>> it) I now have a working system.  I started trying different combinations 
>>>> of DVI/M100/cable (of which I have 2 each).
>>>> 
>>>> DVI #2, M100 #2, Cable #2, no luck
>>>> 
>>>> So I swapped out M100 #2 (32K) for M100 #1 (24K/REX), and it worked!
>>>> 
>>>> It’s still a little finicky and doesn’t always work, but has worked 
>>>> multiple times now.  I don’t know if there’s anything I can do to “tune” 
>>>> it so it’s more consistent, but I”m pumped that I finally got it to work.
>>>> 
>>>> I had tried this M100/cable combination with DVI #1, so I’m wondering if 
>>>> there’s an issue with that DVI.  There also must be an issue of some sort 
>>>> with M100 #1 as the current DVI/cable setup didn’t work with that machine, 
>>>> but does with the other.
>>>> 
>>>> This sure seems like a finicky setup.  I would love to see a modern DVI 
>>>> replacement, perhaps with SD card for disk and video output, that would 
>>>> take up far less desk space and be more robust.
>>>> 
>>>> Thanks all!  Any other suggestions for troubleshooting why the M100 (#2) 
>>>> doesn’t work with this and also why DVI #1 doesn’t work with either M100 
>>>> would be much appreciated.
>>>> 
>>>> Randy
>>>> 
>>>> 
>>>> > On Feb 17, 2018, at 4:22 PM, Randy Kindig <randall.kin...@gmail.com 
>>>> > <mailto:randall.kin...@gmail.com>> wrote:
>>>> >
>>>> > I was just thinking the same thing John.  It’s worth a try.
>>>> >
>>>> > Thanks
>>>> >
>>>> > Sent from my iPhone
>>>> >
>>>> >> On Feb 17, 2018, at 3:07 PM, John R. Hogerhuis <jho...@pobox.com 
>>>> >> <mailto:jho...@pobox.com>> wrote:
>>>> >>
>>>> >> Btw it occurs to me that there are 16 permutations possible there. Not 
>>>> >> so high that you couldn’t do all 16 and see if you ever get different 
>>>> >> results in any of 16 if you haven’t already.
>>>> >>
>>>> >> — John.
>>>> 
>>> 
>> 
> 

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