🚀 go-pugleaf

From a mail message from Mark O'Bryan @ gumby.cc.wmich.edu:
%Howard, could you post a list of what software you know of that works with
%the OverScan mod, either to the group or to me?

I don't use an awful wide variety of software. Things I've used recently
with no hassles include - NeoDesk 2.05, Gulam, UnixWindows, WordFlair (demo),
most desk accessories, miscellaneous GEM programs. Notable hassles are
TurboST (all versions) and WordUp 2.0. I modified zmdm and Uniterm to get them
working properly. Some of the VDI routines clip in a 640x400 (or 640x200)
rectangle; I don't understand why only some do and others don't. (Maybe
G+Plus is saving me some of the time? I haven't tried removing that... Hm.)
Likewise with Line-A, so I don't know where the problem arises just yet.
I know some specific problems from Uniterm, which may also be happening in
other programs - for one, adding a 16 bit integer to any address register
is bad news. Adding to an address register always affects all 32 bits of
the register. If the 16 bit integer has the high bit set, it's treated
as a negative number, so the ADD becomes a SUBTRACT! This happens a lot
in code to calculate drawing offsets from a screen base, and needless to
say, it winds up drawing all over something it shouldn't have - usually
the stack. This is really Bomb city. This usually isn't a problem, since
the maximum offset would ordinarily be 32000 (a nice, safe, positive
integer...). But for larger screens, well... you get the picture.  }-)

%
%I've thought about doing the OverScan mod a couple times (this is the hard-
%ware + software mod, right?), but have held off because I figured it was

Yep, hardware & software.

%of little use if nothing (i.e. most applications) would work with it.  I
%think I've still got all the files for this laying about somewhere.
%
%Does it seem worth the effort to you?  Has the hardware hack made your
%system any less reliable?  Did you install a switch to convert back to
%normal mode?  And to refresh my memory, what exactly are the extended
%pixel resolutions you get?

Hm. It wasn't a heck of a lot of effort, really. I like it, though now
I'm itching to get a multi-sync monitor attached, so I can expand even
further... With an SM124 monochrome monitor, you can get 688x480 pixels.
On the SC1224 color monitor, you get 720x280. I have a toggle switch
coming out the front of the machine to switch between overscan and normal
mode. When I'm into some heavy hacking, I usually use overscan so I get
more code onto a screen in a text editor. I don't think any games work
with it, so I have to switch it off for Falcon and Dungeon Master (for
example... }-). On a multi-scan/multi-sync monitor, you should be able to
get 800x560 or something like that. (I don't remember the exact numbers
offhand.)

--
  -- Howard Chu @ University of Michigan