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Thread Tools Display Modes
Old 07-03-2017, 02:12 PM   #1
Neville
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Default CGA, Hercules, EGA and other older display modes explained

PCs started as business machines, and only later were introduced into homes or considered as capable videogame machines. Therefore, it shouldn't be a surprise that their graphical abilities were much behind other computers of its time, such as the Apple II, the Atari ST or the CBM Amiga. It was later, thanks to different hardware upgrades, that PCs became what we know today.

Therefore, if today we deal with old games we may be given several obscure (for some people, at least) options to choose from.

CGA - From 1981. Allows up to 320x200 in resolution with 4 simultaneous colors or 620x200 in B/W. Believe it or not, this was an upgrade from the original MDA text-only mode that's rarely seen in games.

CGA is often criticised because of its lack of color variety. In the 320x200 modes only two palettes are available: either red, green, yellow and white, or cyan (pale blue), magenta, black and white. The motives behind this were both economical (the card only needs 16 Kb. RAM to work) and corporative, because IBM favored their office customers over the gaming community.

Hercules - From 1982 onwards. It can show graphics up to 720x350, but only in B/W. Developed by an external company, it tried to combine the main virtues of MDA (its text mode, better than CGA's) and CGA (its highest resolution, two color graphic mode) for a lower cost. It could use B/W, green and orange monitors and it was likely the best option for them.

With the help of a CGA software emulator, it could also display regular CGA modes, but always without colors.

EGA - From 1984. 64 Kb. RAM. Up to 640350 in resolution and 16 simultaneous colors. CGA compatible.

MCGA - From 1987. Only available in some IBM PS/2 models. Has some 256 color modes available. It's CGA compatible, but not EGA compatible.

VGA - From 1988. 256 Kb. RAM. Up to 800x600x256 colors. Is compatible with previous display modes CGA and EGA (official modes only), but not with Hercules. Trying to show Hercules graphics in a VGA card will result in CGA graphics.

The most used graphic mode (320x200 and 256 colors) is common to MCGA, so some games refer to these graphics as MCGA/VGA.

SVGA - From 1989. Up to 1024x768 and 64k colors. Manufacturers didn't agree on the exact specs, and the VESA standard was later created as a solution. That's why some programs require a VESA compatible video driver in order to work.

Then there are the IBM PCjr. and Tandy 1000. These aren't graphic modes, but two PC models using a CGA card with some extra 16 color modes thrown in. Regular PCs can't access these modes.

More info on them available at:

Code:
https://en.wikipedia.org/wiki/IBM_PCjr
Code:
https://en.wikipedia.org/wiki/Tandy_1000
A few pre-1990 games can be set up under DOSBox or PCem to run into PCjr. / Tandy modes, such as "Arcticfox", "Marble Madness" or "Ninja". This has the advantage of showing 16 colors and 3-channel music and FX.

Now let's see and old game, "Prince of Persia" from 1989, running in different modes:



CGA mode, using a 320x200 resolution and its second palette: cyan, magenta, black and white.




Hercules mode: a higher resolution, which results in sharper graphics, but in B/W only.




This is what we get in a PC with an EGA card or a PCjr. / Tandy computer.




And finally, the same game with VGA and newer cards.

Last edited by Neville; 08-12-2018 at 06:51 PM.
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Old 07-03-2017, 02:34 PM   #2
Neville
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Default

When dealing with post-1990 games, options will be usually more restricted. Usually those games will only run in VGA and SVGA modes.

Examples of these hybrid VGA-SVGA games are a lot of mid-1990s First Person Shooters, such as "Duke Nukem 3D", "Blood" or "Quake".

Now let's see one of those games, "NASCAR Racing" (1994) from Papyrus:





Ideally, one would set up the game to run in SVGA mode (second picture), but in its time people with older computers had to stick to VGA mode, which was less demanding. This was before accelerated 3D cards became usual, mind you.

Speaking of which, towards 1995 a ton of different 3D accelerator cards flooded the gaming market: Matrox Millennium / Mystique, PowerVR, S3 ViRGE... The only ones currently emulated are the 3Dfx Voodoo, which became the first standard until 2002, when 3Dfx Inc. filled for bankrupcy. Since their departure, the 3D card market has become mostly a fight between NVIDIA and ATI - AMD.

If you have a game that supports 3Dfx acceleration, there are several options in order to enable it:

- If the game runs under DOS, try the unofficial DOSBox release by Yhkwong.

- If the game runs under Windows, you will need a Glide Wrapper, a program that "translates" the Voodoo instructions into modern APIs like DirectX or OpenGL. nGlide or dgVoodoo are two good choices.

Note that a Glide Wrapper won't necessarily make your game compatible with the version of Windows you are running. You may need to fiddle with the compatibility options or update your game in order to play.

- A third option is to create a Windows 9X installation under PCem. This will require a very powerful computer and to install the necessary Voodoo drivers.



PCem running "Quake 2". Picture taken from its website.

Last edited by Neville; 08-12-2018 at 06:55 PM.
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Old 07-03-2017, 03:06 PM   #3
Neville
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Finally, let's see some unusual video modes that are currently available only through emulation.


1) The CGA Composite mode:

As we said before, CGA mode offers only 4 colors at the same time, period.

However, under very specific circumstances a 160x200 mode with 16 simultaneous colors could be used. For this, you needed a CGA card with a composite video output and a NTSC monitor.

Many pre-1990 games support this graphic modes.

Here's an example, "Tournament Tennis" (1985) from Imagic.



Regular CGA mode



CGA Composite mode

This video mode can be emulated through DOSBox (although you'd better obtain a SVN copy) and PCem.

Here's a list of videogames that support this graphic mode:

Code:
http://www.mobygames.com/attribute/sheet/attributeId,29/

2) PCjr. / Tandy graphic modes.

The IBM PCjr. and the Tandy 1000 were two computer models released around 1984 that, while remaining mostly PC compatible, tried to expand its capabilities for home / videogame use.

In addition to the CGA Composite mode, they could access several other exclusive modes, such as 160x100x16, 320x200x16 and 640x200x4.

They also upgraded the internal PC speaker to a three-voice model and, in some late Tandy 1000 models, added a DAC.

The IBM PCjr. was an inmediate failure, but the Tandy 1000 and its variants stayed on the market until the early 1990s, meaning that hundreds of games from that era offer some kind of support for them.

Here's a list of games that support PCjr. / Tandy graphics:

Code:
http://www.mobygames.com/attribute/sheet/attributeId,31/
There are even a few games where PCjr. / Tandy is the best graphic mode available. Some examples are "Arctic Fox", "Boulder Dash" I - II, "Marble Madness", "Ninja" and "Shanghai" from Activision.





"Ninja", in CGA and Tandy modes.


The PCjr. / Tandy computers can be emulated both in DOSBox (although, again, you'd better obtain a SVN copy) and PCem.

Last edited by Neville; 08-03-2017 at 02:39 PM.
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