Riddle - Scrambled Minerva

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mk79
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Riddle - Scrambled Minerva

Postby mk79 » Wed Jun 24, 2020 4:15 pm

While testing my new QL-SD ROM adapter I got the following screen. I found it quite funny, anybody want to venture a guess how something like this could happen?
minerva_scramble.jpg


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NormanDunbar
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Re: Riddle - Scrambled Minerva

Postby NormanDunbar » Wed Jun 24, 2020 4:33 pm

Hi Marcel,

I would hazard a guess, the font pointer in the channels are all not pointing at the correct ROM location for the font set? Now, how that could happen, I have no idea.


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Re: Riddle - Scrambled Minerva

Postby tofro » Wed Jun 24, 2020 5:21 pm

Finnish Minerva ROM? ;)

No. Code from ROM seems to work OK, otherwise we wouldn't see anything. I know the Minerva Bitmap is a pixmap in the Minerva ROM, and that seems to work alright as well. Is Minerva running from the near or the far side of the ROM port? I guess near.

There seems to be an at least somewhat orderly shift in characters - All spaces are "?", "F" is transformed to "e", "1" to "O", 2 to "P", "3" to "R", "4" to "S" - But superscript "F" shows up too often, as well as "ä", so it's not as orderly as I first thought . I had first assumed you got an address or data line interchanged, but then the code wouldn't have run so far.

A solder joint between some upper address lines, perhaps (larger than $C000)?

Tobias


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Re: Riddle - Scrambled Minerva

Postby Derek_Stewart » Wed Jun 24, 2020 5:44 pm

Hi,

There could 2 possible reasons, either a hardware fault or software fault/corruption.


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Derek
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Re: Riddle - Scrambled Minerva

Postby pjw » Wed Jun 24, 2020 6:04 pm

mk79 wrote:While testing my new QL-SD ROM adapter I got the following screen. I found it quite funny, anybody want to venture a guess how something like this could happen?
I had something like this with Minerva for a while. Too long ago to remember what the trouble was or how it was resolved.
Youre welcome ;)


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Re: Riddle - Scrambled Minerva

Postby mk79 » Wed Jun 24, 2020 7:25 pm

OK, I'll solve :-) It was quite obvious when you have the QL in front of you but almost impossible to guess when not... though Tobias analysis came close with problems in the upper area.

Anyway, I forgot to remove the internal QL-SD before plugging the external one in. So there were two ROMs running at the same time! The twist is that one ROM was a German Minerva and one ROM was an English Minerva. These are in large parts identical as the language specific part is towards the end... so they agreed enough on the code to make it run flawlessly, but when they tried to access anything language specific they strongly disagreed and the result was garbage on the data bus :-) Still, thought this effect was interesting enough to share.


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Re: Riddle - Scrambled Minerva

Postby tofro » Wed Jun 24, 2020 7:30 pm

Funny. Bi-lingual QL. Could be called "the tower-of-babel-syndome"

They can't have been 100% in sync - I would have assumed that at least the "F1/F2" and "F3/F4" texts which are identical in English and German Minerva should have shown up?


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Re: Riddle - Scrambled Minerva

Postby NormanDunbar » Wed Jun 24, 2020 8:26 pm

Well, that was going to be my next guess! (I lied!)

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Norm.


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Re: Riddle - Scrambled Minerva

Postby swensont » Wed Jun 24, 2020 8:27 pm

Wow, Nice to see that you have the QL doing Klingon :-)


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Re: Riddle - Scrambled Minerva

Postby mk79 » Wed Jun 24, 2020 11:13 pm

tofro wrote:They can't have been 100% in sync - I would have assumed that at least the "F1/F2" and "F3/F4" texts which are identical in English and German Minerva should have shown up?
Due to different sizes of the texts before the F1/F2 text they end up at different addresses. And presumably the address fetched will not point to either of the versions as it must be garbled, too.



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