Conference 7.286::atarist

    I noticed an ST magazine at Munich airport on Monday, which may be what
    you are referring to. I'm going through again on Fri (12th), so I'll
    check it out further.
    Jim Burke

>    article in the May ST68000 Magazine, that tells how to increase the
>    resolution of the ST screen displays. (800*500 ???) 


I read the article and found it *very* interesting. I will post the details
tomorrow (article is at home).

abstract: 
there are Graphic demos by some hackers in Europe where
graphics are displayed above and below as well as to the right and the left of 
the normal screen window. This is done by switching between 50Hz and 60Hz mode
by an interrupt routine at the right moment. (assembler listings and docs were
in the St68000 mag last year) 

Analizing the timing of the signals on the video hardware showed them that one
signal defines a time window during witch the video shifter reads memory and 
shifts the dots (=bits) out to the monitor. The Atari does not use the full
possible timeframe hence leaving blank space around the screen window.

A new signal is generated by logical or-ing two signals via two diodes, one 
transistor, and a resistor. This makes it necessary to reserve more memory
for the video and tell the TOS about it. As per default the GEM is resolution
independant and properly written programs are, too, the new resolution of
800 times 500 is used without problems. The necessary software for the new
memory management is contained on a disk witch must be purchased seperately.
(listing too  long, but ~1200 bytes in hex with checksums every 16 bytes in 
the mag for people who cannot wait until the disk comes out).

MORE INFO FOLLOWS

---markus---

    Some comment on the Usenet about this was that a) it isn't very reliable
    when it works, and b) the software only works with the 6/85 RAM
    TOS (pre-1.0), not the ROM TOS versions now available.
    
    I wouldn't personally know either way...
        fred

Here is more info now, as I have my magazine at hand...

The following is posted without any permission of the author/publishers.
Also I can not give all the details here (it's too much).

I would therefore strongly recommend to buy the magazine (Mai issue 89)

ST68000 Magazin                          US representativs:
Markt & Technik Verlag AG                M&T publishing inc
Hans Pinsel Strasse 2                    501 Galveston drive 
8013 Haar/M�nchen                        Redwood City, CA 94063
Germany            tel 089/4613-0        tel (415) 366-3600

As stated in my previous reply, it is an electric signal that defines a time
frame within witch the memory is read byte by byte and being displayed on the
screen. This is the DE (data enable) on the GLUE chip and the MMU. The idea 
is just to replace this signal by another with the maximum on/off rate possible 
within the overall video timing. A lot of investigation had been done to find 
the right signal. Some obvious ideas had to be dropped because of software
problems during bootphase, others did not work at all.

Finally the author ended up in using a composite sync signal. But it is not 
possible to simply feed it to the DE of GLUE and MMU because of boot problems.

Also it is necessary to build this signal by your own. This is done by 'adding'
the vsynch and the hsynch through 2 diodes and a transistor. The author gives 
detailed explanation of where on the board to find them. It is strongly 
dependant of type of ST (520,1040,Mega) and the revision of the board.

The new timing signals and the old can be selected by switch, so your ST can
behave like it always did.


Hardware:
--------
Cost of the neccessary hardware: around 3 DeutschMark / $2.
1 switch
2 resistors 240 Ohms/10k respectivly
1 Transistor BC555 or similar (npn type)
2 diodes 1N4148
1 capacitor 100 nano 

Software: (some parts of the article in free translation)
--------
...one can switch between the two modes without crash or reboot. The only
problem that can arise is that the colorpalettes are messed up due to bouncing
of the switch. Just switch back and forth once again. Of course one needs
software for the new features. We have written a simple GFAbasic program for
patching the 1.4 TOS beta release... You can then boot with that new TOS in
Hyperscan mode. Sometimes there may be colorpalette shifts. Just toggle the
switch...

...first we had to use a patched RAM TOS. The patch program can be found on
our reader service disk. But then we found a way to manipulate the ROM TOS.
A short program in the Auto folder tells GEM about the larger memory area to
put aside for the screen. Hyperscan works with all 3 resolutions, because
the size of the memory is always the same, just its usage differs. The listing
and a compiled version can be found on the service disk, too...

Future:
------
In the next issue (June) there will be more about screen management under
Hyperscan. Also they will post a list of software that uses the higher 
resolution. Per default properly written GEM programs should be resolution
independant. With the coming new large screen for the Atari more and more
software houses are currently revising their products to conform to the
GEM standards.

From: [email protected] (Andreas Toenne)
Newsgroups: comp.sys.atari.st
Subject: Re: increased resolution on normal ST (50%)
Date: 2 May 89 18:40:20 GMT
Organization: University of Dortmund, W-Germany
Posted: Tue May  2 19:40:20 1989
 
In article <[email protected]> [email protected] (James Parker) writes:
>In article <[email protected]> [email protected]!clutx.clarkson.edu.UUCP writes:
>>From article <[email protected]>, by [email protected]:
>>> in the german magazine 'ST magazine' dated 5/89 there is a discription of
>>> a extremely simple and low-cost (2 dollar) change discriped, that gives
>>> the atari a resolution of 840*568 points (on a normal atari monochrome
>>> monitor sm124/125)
 
FOLX!
 
HANDS OFF!!!!
 
I talked to several people who tried this patch. It involves some soldering
on your Atari board and new software. 

However, nobody could claim that this patch works. Obviously the software
is faulty and the hardware patch does not work properly. 

It should expand the 'writing' time of the kathode-beam such that you can
write on the black borders around the screen. But you'll see the beam when
it runs back on the same space in monochrome mode. 
 
	Andreas Toenne
 
P.S. I would like to have such a goodie too

     The software for this project just came over usenet, you can get the
  sources from comp.sources.atari.st

  Bill Powers