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-
- SIMCGA - A CGA SIMULATOR FOR MONOCHROME
- GRAPHICS CARDS
-
-
- SIMCGA and this document copyright 1987 by C. P. Guzis
- All rights reserved.
-
- Reproduction of SIMCGA or this document is prohibited
- without the express written permission of C. P. Guzis.
-
- ------------------
-
- This is version 4.0 of SIMCGA, released in July of 1987. If you
- have questions or inquiries concerning this product, please be
- sure to mention that this is the "July 1987" version of SIMCGA.
-
-
- -WHAT IS THIS PROGRAM?-
-
- SIMCGA is a program written for those IBM PC or "compatible"
- users who have a Hercules Monochrome Graphics adapter card or
- Hercules-compatible display adapter and would like to be able to
- run programs requiring the IBM Color Graphics display adapter
- facility.
-
-
- -WHAT WILL AND WON'T WORK?-
-
- Because SIMCGA is a software product, there are certain hardware
- limitations on its use. Programs which access the Color Graphics
- Adapter hardware registers directly generally will not operate in
- a satisfactory manner - the hardware just isn't there to interact
- with! In general, try running the program - you won't clobber your
- disks if it doesn't work.
-
- SIMCGA will not work with a plain old IBM monochrome adapter or-
- with an Enhanced Graphics Adapter (EGA).
-
- Version 4.0 incorporates support for non-DOS diskettes which con-
- tain their own operating system rather than using DOS.
-
-
- -WILL SIMCGA RUIN MY MONITOR?-
-
- No. SIMCGA programs your display adapter so that the frequencies
- generated are very much within the specifications of your
- monochrome monitor. (18.5 KHz horizontal and 53 Hz vertical).
- However, you should avoid using programs which will cause
- problems with a Hercules or Hercules-compatible card. Most
- "screen-saver" programs are in this category and may cause damage
- to your monitor whether or not you are using SIMCGA.
-
-
- -HOW DO I USE SIMCGA?-
-
- To run SIMCGA, copy the programs (all files ending with .COM) on
- this disk to the directory or diskette where you normally keep
- your system programs. Then decide if you want to run in "stand-
- alone" or DOS mode. Standalone mode is used with programs which
- "boot up" without DOS; many games fall in this category. DOS mode
- is used with programs which require DOS to execute. In either case,
- first load DOS.
-
- If you want to run a "standalone" program, enter -
-
- SIMCGA S<Return)
-
- (<Return> means press the "Return" key on your keyboard). SIMCGA
- will display the product notice and request that a program diskette
- be inserted into diskette drive "A". Place the diskette containing
- the program you wish to run in the "A" drive and press any key. The
- program will be loaded and begin execution in CGA emulation mode.
- To remove SIMCGA from your computer, turn the computer's power switch
- off, then on again. A Ctl-Alt-Del keyboard reset will, on most com-
- puters, also cause SIMCGA to disappear.
-
- If you want to run a DOS-based program enter -
-
- SIMCGA<Return>
-
- (<Return> means press the "Return" key on your keyboard).
- SIMCGA will load its resident part (or tell you why it won't) and
- set your display to 80x25 color text mode. Your display adapter
- will appear to be a Color Graphics Adapter board to most programs
- accessing it.
-
- To resume ordinary monochrome text operations, enter -
-
- MONO<Return>
-
- To go back to CGA 80x25 mode, enter -
-
- CGA<Return>
-
- To set 640x200 high-resolution graphics mode, enter -
-
- HIRES<Return>
-
- To set 320x200 medium-resolution graphics mode, enter -
-
- MEDRES<Return>
-
- For most applications, MONO and CGA will suffice to set either
- monochrome or graphics modes.
-
- To completely remove SIMCGA from your computer's memory, enter -
-
- RMVCGA<Return>
-
- Like the standalone mode, the DOS mode SIMCGA will disappear
- with a Ctl-Alt-Del keyboard reset.
-
- If you desire, you may also run DOS as a standalone program.
- Just insert your DOS diskette when the program diskette is re-
- quested.
-
- -IF YOUR PROGRAM RUNS TOO SLOWLY-
-
- Some programs, especially games, require large amounts of atten-
- tion from your computer. SIMCGA also requires some of your com-
- puter's attention to keep the display looking good. If you find
- that there is not enough computer to go around, you may instruct
- SIMCGA to use less of your machine's resources. However, nothing
- is free, and the display will exhibit more "ghosting".
-
- To change the amount of time SIMCGA "steals" from your application,
- use a number from 0 to 9 on the SIMCGA command line. 0 tells
- SIMCGA to use the largest portion of your computer's power to
- maintain the display; hence programs will run more slowly. 9 tells
- SIMCGA to use the least practical amount of your computer's
- power to maintain the display; you will however, see the greatest
- amount of "ghosting". If you are using SIMCGA in the "standalone"
- mode, the number may either precede or follow the "S" parameter.
-
- For example -
-
- SIMCGA 3<Return>
- SIMCGA S 2<Return>
- SIMCGA 5S<Return>
-
- are all forms that SIMCGA can understand.
-
-
- -"IT LOOKS LIKE I'M LOOKING THOUGH A SCREEN WINDOW"-
-
- If you're running a program (most likely a game) and you notice
- that the display has fine black lines running horizontally across
- it, try using SIMCGA up with the letter "I" on the command line.
- This has to do with how SIMCGA deals with the timer on your com-
- puter, but should not otherwise affect program operation. The
- "I" parameter may be combined with any of the others.
-
- For example -
-
- SIMCGA I
- SIMCGA I 2
- SIMCGA 3SI
-
- are forms acceptable to SIMCGA.
-
- -THINGS YOU MAY NOTICE-
-
- "Ghosting" of moving graphics images - this is just the way the
- program operates and is nothing to be worried about.
-
- Some lines are thicker than others in graphics mode - SIMCGA
- fills out the displayed image by "doubling" every other line.
-
-
- -COMPATIBILITY-
-
- When you run SIMCGA, you may get a message to the effect that
- SIMCGA has detected that your monochrome graphics adapter is not
- CGA-compatible. What this is trying to say is that not all
- "clones" -accurately- reproduce the functionality of the Hercules
- monochrome graphics adapter. SIMCGA will attempt to make the
- best of the situation; however, the simulation may not be perfect
- in the 80x25 and 40x25 CGA text modes. Graphics modes will work
- correctly regardless of the brand of monochrome graphics adapter
- used.
-
-
- -DISTYPE - DETERMINE DISPLAY TYPE-
-
- A utility program for use in batch files is provided for the purpose
- of determining the type of the current active display adapter. DIS-
- TYPE may be invoked by the following statement -
-
- DISTYPE
-
- DISTYPE returns an error code corresponding to the display adapter
- configuration found -
-
- 0 A monochrome adapter with no graphics capabilities has been
- detected.
- 1 SIMCGA is currently installed with a monochrome graphics
- adapter.
- 2 A Color Graphics Adapter (CGA) is in use.
- 3 An Enhanced Color Graphics Adapter (EGA) is in use.
- 4 A monochrome graphics adapter (HGC) is installed, but SIMCGA
- has not been run.
-
- The code returned by DISTYPE may be queried by use of the DOS "IF
- ERRORLEVEL" statement (consult the DOS reference manual for details).
- Here is an example of the use of DISTYPE in a batch file -
-
- ECHO OFF
- DISTYPE
- IF ERRORLEVEL 4 GOTO DOSIM
- IF ERRORLEVEL 3 GOTO EGA
- IF ERRORLEVEL 2 GOTO CGA
- IF ERRORLEVEL 1 GOTO SETCGA
- ECHO *** ERROR ***
- ECHO GRAPHICS ADAPTER REQUIRED
- GOTO QUIT
- :DOSIM GOT HGC WITH NO SIMCGA YET
- SIMCGA
- GOTO QUIT
- :EGA GOT EGA, OKAY
- :CGA GOT CGA, OKAY
- GOTO QUIT
- :SETCGA SIMCGA AROUND, ENABLE EMULATION
- CGA
- :QUIT COMMON EXIT POINT
-
-
- -----------------------
-
-
- "Hercules" is a trademark of Hercules Computer Technology; "IBM" is a
- trademark of International Business Machines Corporation.