Current Shareware 1994 January/SHAR194.ISO/dos_util/pcl61b.zip/PART6.ZIP/DISPLSTD.TUT

Text File | 1993-08-16 | 12KB | 197 lines

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               DISPLAY STANDARDS - WHY SOME PROGRAMS WON'T RUN!

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       All beginners must at some point learn the compatibilities of
       software, the monitor and the video display circuit cards
       attached to a computer. Your monitor is usually matched to a
       video circuit board within the computer. You can change the
       monitor and video circuit board to add color or upgrade to
       higher resolution color as you wish. The computer remains the
       same but the visual clarity changes!

       Many software packages allow several types of display in color
       or monochrome with varying degrees of resolution. These types of
       displays are listed below. Both the monitor and the video card
       within the computer determine the type of color and resolution
       which you see. Color quality and resolution can be changed by
       buying a different monitor and replaceable video circuit board.

       MONOCHROME DISPLAY ADAPTER or MDA refers to text (characters,
       letters and numbers) produced by a circuit card within the
       computer. A monochrome monitor is typically manufactured to
       produce green or amber letters on a dark field. A monochrome
       monitor is usually mated to a monochrome circuit board (card)
       inside the computer. MDA was the first IBM graphics display
       standard and supports older software packages but is not
       considered a modern standard. It is of utility for simple
       software needs - perhaps word processing and accounting use.
       Resolution or clarity of the image is fairly low with a
       structure of glowing dots or pixels making up the image. 720
       dots accross the width of the screen by 350 vertically. Thus
       known as 720 x 350 resolution.

       HERCULES is a reference to a higher resolution monochrome
       standard. Hercules circuits usually drive or operate a
       monochrome monitor. By itself a Hercules circuit card CANNOT
       drive a monochrome monitor when you try to run a COLOR software
       package. Low priced computers frequently have Hercules display
       resolution and may have trouble displaying color games or
       graphics software on the monochrome Hercules circuit. Result: no
       display. Solution: obtain alternate software or purchase a true
       color monitor and color video circuit for the computer. Some
       models (Hercules Incolor card) offer up to 720 x 348 dot
       resolution. Hercules cards and monochrome monitors are a fair
       choice for office use where a color display is not necessary.
       Hercules display resolution is an affordable compromise for a
       low end PC for light office and home use where color is not
       required.

       Owners of older Hercules circuit boards who wish to use CGA or
       color software can try loading and running small software
       emulation programs which help a Hercules monochrome display card
       emulate CGA color mode. This is a "poor man's solution" which
       lets you display CGA color software on your monochrome monitor.
       You will only see shades of gray, but at least the software can
       display on the screen. Examples of these types of emulation
       programs for Hercules cards include the shareware program
       SIMCGA.COM and CGA.COM. Slight screen flicker may be apparent
       when using these CGA emulation programs.

       CGA (color graphics adapter) refers to the first IBM low
       resolution color display circuit. Color monitors and CGA circuit
       boards (cards) are usually mated together in this scheme.
       Alternatively, CGA color circuits can operate a monochrome
       monitor, but results can be unpredictable depending on the
       software program. Some color software programs produce faint or
       flickering images when a CGA color circuit operates a monochrome
       monitor. Of course, when a CGA circuit card operates a
       monochrome monitor, only black and white images can be seen. 640
       x 200 dot resolution. Many games and good quality home and
       office software packages exist for CGA display and it is of fair
       quality for light office use.

       Some older CGA equipped computers have a monochrome monitor and
       can sometimes improve visual display by 1) slightly increasing
       screen brightness with the monitor light/dark control, but be
       careful! 2) using the DOS mode setting to switch the CGA circuit
       board to its black and white output (example: mode bw80). 3)
       Searching the software instructions for resetting the software
       package itself to display in other color shades which can be
       seen clearly on the monochrome monitor.

       EGA (enhanced graphics adapter) is high resolution color display
       circuit. The EGA card typically operates or drives a special
       high resolution EGA monitor. Most modern software packages
       support color EGA. Is is a popular, although not completely
       modern display standard. Up to 350 x 720 dot resolution. A
       reasonable compromise for cost conscious computing in a wide
       variety of home or office settings. Usually several software
       disks accompany the EGA circuit card to assist changing
       resolutions, colors and display fonts. Most EGA circuit cards
       can, under software control, "downshift" to run older CGA and
       monochrome resolution older software. A handy bonus.

       VGA has higher resolution and requires a still higher
       performance monitor and is considered a modern standard. VGA
       color monitors are somewhat expensive, but buyers can opt for a
       VGA monochrome monitor screen which is quite affordable if high
       resolution is desired, but color is not necessary. VGA cards can
       also "downshift" and run older software packages, including
       older CGA, EGA and monochrome software. Usually a software disk
       accompanies a VGA circuit card to assist changing resolutions,
       colors and display fonts. VGA features either 320 x 200 pixel
       resolution with 256 colors or 640 x 480 pixel resolution with 16
       colors.

       SUPER VGA or SVGA. This is a rapidly evolving display circuit
       which is NOT yet widely standardized. A wide variety of
       manufacturers sell SVGA circuit cards which move to still higher
       resolution but are NOT widely standardized among themselves.
       Resolutions of 800 x 600 and 1024 x 768 pixels are available. The
       key here is to consult with the manufacturer of your software to
       see if it will run with that SVGA display resolution. Typically
       a call to your software dealer will provide information if a
       special software "driver" utility is available for that SVGA
       circuit card which will operate with your software.

       Standard VGA cards with older "8 bit interfaces" will run on
       original 8088 processor-equipped IBM PC's, although you may need
       to supply a special software driver, replace a BIOS circuit chip
       within the PC or both. Newer "16 bit" VGA cards are available -
       and generally preferred - due to faster screen display times.
       Generally it makes sense to install a VGA card, expecially the
       16 bit versions, on computers having 80286 or 80386 processor
       chips since the faster processor and wider 16 bit data bus can
       better support the overhead of moving those extra pixels around
       the screen.

       Occasionally compatability problems have been reported with a
       few VGA circuit cards running on computers operating at 12.5 MHz
       or above. Ask your vendor to guarantee refund or replacement if
       compatability with your PC or software fails.

       XGA is a newly emerging video display standard for IBM
       compatible computers. The majority of software packages do not,
       as yet, completely support this high fidelity color resolution.
       Likewise a newly emerging 8514 display standard is under
       development by IBM.

       Do not overlook the role of the monitor. While the display
       circuit card within the computer moves data around, it is the
       monitor that will affect your eyes most directly. For the budget
       conscious, monochrome "gray scale" VGA monitors are available.
       The buyer may wish to investiage various color "multisync" or
       "multiscan" monitors which automatically adjust to a wide
       assortment of VGA, EGA or CGA color circuit cards. Watch out
       though, since some "multiscan" monitors synchronize only to VGA,
       yet when emulating EGA will display a small picture in the
       middle of a large blank screen. Not entirely favorable. Try a
       variety of software packages you might use at a variety of
       display resolutions to make sure that BOTH the circuit card and
       monitor work together as a team.

       Most display schemes are "downward compatible". This means that
       a high end VGA card can, through software command, be switched
       downwards into EGA, CGA or Hercules modes. Many utilities are
       available to help you set the color spectrum and output quality
       of EGA and VGA display circuits. The trick is to determine what
       display circuit standard you have (VGA, for example) and use
       software which will work with that display resolution. Of course
       you can always upgrade to a higher standard by swapping both the
       monitor and display card. Older users or those with eye
       difficulties may actually prefer lower resolution, larger text
       images. Thus if you have a VGA card, you may actually NEED to
       switch to low resolution (larger typface) CGA mode!

       For the most part monochrome is satisfactory for light office
       use, Hercules is adequate if you need to do graphing and text
       work, CGA is useful for games and other types of color graphing.
       Some owners find that their computer contains an EGA card, for
       example but they only have a simple monochrome monitor. The
       upgrade path here is simply to replace the monitor and retain
       the existing video circuit card.

       Final thought for the bewildered beginner: find out from your
       instruction book or computer salesperson which video circuit
       card (CGA, Hercules, etc) is contained inside your computer.
       Determine which type of monitor you have. Finally check software
       purchases to be sure the software package will display properly
       with that equipment combination. Consider purchase of an
       alternate display circuit card if the software you need does
       not display with your computer. If you use the machine mostly
       for office use, monochrome or Hercules text mode is fine. For
       more sophisticated design, graphics or intensive office use
       VGA color adds clarity.

       Tutorial finished. Have you registered PC-Learn to receive your
       bonus disks? Registration is encouraged. Shareware works on the
       honor system! Send $25 to Seattle Scientific Photography,
       Department PCL6, PO Box 1506, Mercer Island, WA 98040. Latest
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