Dec 242017
 
MGSVGA2 allows Magellan 2.0 to operate in extended text modes like 132x25, 132x43 or 132x50 on Super VGA cards.
File MAG2.ZIP from The Programmer’s Corner in
Category File Managers
MGSVGA2 allows Magellan 2.0 to operate in extended text modes like 132×25, 132×43 or 132×50 on Super VGA cards.
File Name File Size Zip Size Zip Type
BITMAP.VW2 9305 5914 deflated
COLCOUNT.EXE 25997 10873 deflated
MGSVGA.EXE 19171 18546 deflated
MGSVGA2.COM 3232 1036 deflated
MGSVGA2.TXT 6723 2787 deflated
MGSVGA2M.COM 3232 1036 deflated

Download File MAG2.ZIP Here

Contents of the MGSVGA2.TXT file


** Magellan 2.0 Extended Text Mode Loader **

The attached loader program, MGSVGA2.COM, is designed to allow Magellan
2.0 to operate in extended text modes like 132x25, 132x43 or 132x50 on
Super VGA cards where using MG.COM causes the display to reset to 80x25.

To install the loader, simply copy MGSVGA2.COM into your Magellan
directory, and then use MGSVGA2 to start Magellan, instead of MG. The
loader installs a small section of code to answer Magellan's video mode
requests, and then loads MG.COM. If you are using MGMOUSE.EXE from the
Magellan 2.0 Bonus Viewers Disk, put the following command in your
AUTOEXEC.BAT file:

SET MGMOUSE=/PMGSVGA2.COM

You can then start Magellan using MGMOUSE, same as before. If you use a
batch file to start Magellan, change the batch file appropriately.


** Technical Background **

All video modes have an ID number in the ROM BIOS by which they can be
identified. The industry standard ROM BIOS defines normal modes like
80x25, CGA, EGA and VGA graphics, and Hercules. Extended text and
graphics modes such as 132x25 text or 800x600 graphics are not assigned
industry-standard ID numbers.

Software-based screen-extenders, such as Ultravision, by Personics,
produce extended text modes on a VGA or SuperVGA card via software,
without changing the video mode ID. Thus a machine that starts out in
mode 3 (normal 80x25 VGA text), and is changed to 132x43 by
Ultravision, will still report mode 3 to software applications.

Hardware-based screen modes, however, such as those built into SuperVGA
cards from companies like ATI and Paradise, often use unique ID numbers
to identify their extended video modes. The ATI VGAWonder card uses
mode numbers in the 20s and 30s (hex), defining 132x25 text as mode
23h, and 132x43 text as mode 33h. The Paradise SuperVGA circuitry built
into a number of clone machines uses mode numbers in the 40s and 50s
(hex) to identify the same functions.

Because there is not yet an industry standard for how these extended
modes should be numbered, if Magellan encounters a mode number that it
cannot identify, it is forced to assume that the mode could be
incompatible, and it resets the screen to a normal 80x25 text mode.
This means that while Magellan can correctly recognize extended text
modes created by Ultravision and similar software products, it often
cannot recognize extended text modes built in to SuperVGA hardware.

The MGSVGA2.COM loader program simply installs an interrupt handler that
intercepts video mode ID requests and returns 3h, for normal 80x25 text,
in place of the manufacturer's ID. Magellan thus thinks that the screen
is in an acceptable text mode ID, and will then load using however many
columns and rows the mode uses. This will, in theory, allow Magellan to
operate in any text mode that the screen can handle.

There are five caveats to be aware of:

1) Magellan graphics viewers will only operate in normal 80-column mode,
so if you are using 132 columns, graphics files will be displayed using

the Generic Text viewer.

2) If you are somehow loading Magellan from a graphics mode, using
MGSVGA2 will probably give you a blank screen, or some strange colors.
This would probably not happen unless you are launching MGSVGA2.COM from
a program you wrote yourself. Put the screen in a text mode and try
again. If you are in doubt about which modes are text and which are
graphics, consult the documentation for your video card, or contact the
dealer.

3) Video mode ID requests from programs launched by Magellan will also
be affected by the loader, so any software that does not reset the mode
itself may be confused to find itself in 132x50 mode when the ID
indicates 80x25. Additionally, any software that DOES reset the video
mode probably won't set the mode back to the extended one afterwards,
putting you back in 80x25 when you return to Magellan. Both of these
problems can be avoided by Launching batch files, rather than the actual
program in questio n, and using the mode-switching utility provided for
your card to switch into 80x25, run the application, and then switch
back into the extended mode. Here are examples for ATI and Paradise
software assuming that Magellan begins in 132x25 mode, and that a
hypothetical application called BUDGET.EXE must be in 80x25 mode to
operate properly:

BUD132.BAT (ATI version)

c:\ati\vconfig vga color
budget
c:\ati\vconfig c132x25

BUD132.BAT (Paradise version)

c:\vgautils\vga vga
budget
c:\vgautils\vga 13225

See your video card's documentation for details on your configuration
software, and the command-line arguments it takes.

4) If you want to run Magellan in an extended text mode under Windows
3.0 Enhanced mode, you will probably want to run Magellan full screen.
Resizable DOS windows will only display 80 columns, no matter what the
card says, and you will find that your Magellan window looks quite odd.
Alt-Enter toggles a windowed application to full screen.

5) If your video card is in a monochrome extended text mode, and we
emphasize that we are referring to the graphics card itself, NOT to the
monitor, you will need to replace MGSVGA2.COM with MGSVGA2M.COM, also
included. This alternate loader remaps extended modes to 7h, which is
the normal 80x25 monochrome ID. Again, if you are using a normal VGA or
SuperVGA card with a monochrome monitor, you should still use
MGSVGA2.COM. Only if the card itself is using a monochrome display mode
should you use MGSVGA 2M.COM. If you try MGSVGA2M.COM and you just get
a blank screen, go back and use MGSVGA2.COM.


** Cautionary Statement for Legal Purposes **

These programs are beta software, and are not part of the Magellan 2.0
retail package. They are provided to you by Lotus Customer Support in
the hopes that they will enhance your enjoyment of Magellan. They have
been tested on the ATI VGAWonder card and on the Paradise SuperVGA
circuitry built into a USA Flex computer, and appeared to function
perfectly in both cases. The code is simple, and will probably work on
anything, but there's always the chance that it won't. Whether it does
or doesn't, we wou ld appreciate hearing which was the case. If you
have any questions or comments, or want to report a success or failure,
please call our PROMPT support number, 1-800-223-1662.


** Files on the Disk **

MGSVGA2.COM (extended text mode loader)
MGSVGA2.TXT (this text file)
MGSVGA2M.COM (special monochrome loader -- see above)
COLCOUNT.EXE (mode-checking utility -- if MGSVGA2.COM doesn't work for
you, this program may help tech support determine why)


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