VMODE.DOC Version 1.0
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Copyright (c) 1986 Raymond Moon ALL RIGHTS RESERVED


INTRODUCTION
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A friend of mine bought a new Zenith 248 which was equipped with an EGA compa-
tible card but soon discovered that the DOS MODE command could not set the
video mode to any of the enhanced EGA video modes. VMODE is a quick, little
program to solve that. Also, many games that use graphics exit without
restoring the screen to the previous mode. Again VMODE is useful and easy way
to reset the screen mode.

BACKGROUND
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It uses ROM-BIOS VIDEO_IO (Int 10h) to set the modes. This program can be
used via the command line or via a menu.

USE
---

VMODE is very easy to use. Just type in 'VMODE' and the following menu is
displayed.

Mode Type Size Colors Adapter
0 Text 40x25 16(gray) CGA,EGA,PCjr
1 Text 40x25 16/8 CGA,EGA,PCjr
2 Text 80x25 16(gray) CGA,EGA,PCjr
3 Text 80x25 16/8 CGA,EGA,PCjr
4 Graphics 320x200 4 CGA,EGA,PCjr
5 Graphics 320x200 4(gray) CGA,EGA,PCjr
6 Graphics 640x200 2 CGA,EGA,PCjr
7 Text 80x25 b\w EGA,MA
8 Graphics 160x200 16 PCjr
9 Graphics 320x200 16 PCjr
10 Graphics 640x200 4 PCjr
13 Graphics 320x200 16 EGA
14 Graphics 640x200 16 EGA
15 Graphics 640x350 b\w EGA
16 Graphics 640x350 64 EGA
Enter desired mode:

Now just enter the number of the desired mode followed by a carriage return.
If all goes well, the screen will blank and the LOGO will reappear in the
new mode.

To use VMODE in the command line mode, just type in 'VMODE XX' where XX is
the number of the desired mode from the above list. If the mode is success-
fully set, VMODE return to DOS with a return code of 0. If VMODE is unsuccessful
fully for any reason, VMODE return to DOS with a return code of 1. This
allows VMODE to be used in batch files and be tested for success.

VMODE only checks to see that the input is one of the above number; no other
checks are made. If the video mode is set to one not supported by your
hardware, the screen will probably just blank. To correct this problem,
just type 'VMODE XX' where XX is a supported mode. This typing will not be
displayed. THIS WILL WORK; YOU DO NOT HAVE TO REBOOT!

ERROR MESSAGES
--------------

VMODE: Need DOS 2.0+
-VMODE can only be run with DOS versions 2.0 or later.

VMODE: Invalid Mode
Aborting...
- Either the entered value on the command line was not one on the above list
or the entered value could not be interpreted. This error only occurs when
in the command line mode and causes VMODE to abort with a return code of
1.

ERROR: Video Mode was not properly set
- The video mode after setting is not the same as requested. It appears that
invalid modes are accepted with the screen going crazy, so this error
message may never be seen.

REQUIREMENTS
------------

VMODE requires DOS 2.0+ and about 1K memory to run.

USER RESPONSIBILITIES
---------------------

- All users are granted to make as many copies of this program as required.
- There are no restrictions on how many different computers one user may use
VMODE.
- Copies may be distributed to others as long as the following requirements are
met:
-- All three files, VMODE.ASM, VMODE.COM, and VMODE.DOC, are transferred as
a whole.
-- These programs are distributed free of cost. Only the cost of the media
(e.g. diskette) can be charged.
-- The files are not modified in any way.
- The source code is distributed with the program to encourage user modifica-
tion to meet individual needs, but in no case will any of these modifications
be incorporated and distributed.
- The author encourages comments. Please leave comments, suggestions, or
suggested modifications in a message on Andy Smith's RBBS (301-956-3396).

DISCLAIMER OF WARRANTIES AND LIMITATION OF LIABILITIES
------------------------------------------------------

The author has taken due care in writing this program, and the program is sup-
plied as is. The author makes no expressed or implied warranty of any kind with
regard to this program. In no event shall the author be liable for incidental
or consequential damages in connection with or arising out of the use of this
program.

PROGRAM INFORMATION
-------------------

VMODE was assembled using Microsoft MASM v3.0 with the /ml and /a switches set.

6 July 1986 Raymond Moon