[MiNT] Q-funk's MiNT problem

[Mario Becroft <mb@tos.pl.net>]

On IRC lately I discussed at length with Martin-Eric Racine the problem he
was having with MiNT on his TT.

It is very perplexing, but as it is quite well defined, at least in
certain respects, it should be possible to debug it.

The problem we discussed relates to the screen display. Q-funk sent me a
screen snapshot which clearly demonstrates the problem. The most striking
fault is that text output to the console, such as the output of a "TTP"
program, gets mangled in a most singular manner. For example the text
"This is FreeMiNT", as in the text displayed by MiNT when it loads,
appears as "Uihr!hr!GsddLhOU."

It appears that each letter is getting changed to a different one
according to a pattern; namely each even ASCII code gets 1 added to it,
while odd ASCII code have 1 subtracted from them. In other words, letters
are swapped in groups of two: B becomes C, C becomes B; D becomes E, E
becomes B etc.

Apparently, this strange behaviour only occurs with MiNT versions later
than 1.15.0. I understand that Q-funk is going to conduct some further
tests to narrow down the problem, but perhaps someone will have some ideas
based on this description.

I cannot think of any reasonable explanation, except that it might be
caused by a virus, but Q-funk explained that he had already checked his
machine with UVK, and no viruses were found.

There is also another problem, in that certain text strings displayed by
the AES in an object tree do not appear. In general, it seems that G_TEXT
objects appear correctly while G_STRING objects are not displayed. However
in many instances of buttons that have an underline below a single
character to indicate a keyboard shortcut, the character with the
underline is displayed while the other characters are not. Again, this
problem only came about in MiNT versions later than 1.15.0, as I
understand it.

I do not observe any of these problems myself, but after conversing with
Q-funk on this subject I believe the above is a reasonably accurate
description. I am perplexed by the symptoms, but I would be most
interested to hear what other ideas anybody has. I'm sure Q-funk would
also be very pleased if he could get MiNT working properly again!

-- 
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| Mario Becroft                * Tariland, New Zealand Atari User Group |
| mb@tos.pl.net                * Atari Hardware Developments            |
| http://www.ak.planet.gen.nz/~mario/ * Atari Serial Mouse Interface    |
+-----------------------------------------------------------------------+