CGA, Hercules, EGA and other older display modes explained

We have come a long way since the first PCs were introduced in 1981. Compared with what we have today, they were ridiculously slow and cumbersome machines which, among other barriers, used a number of display modes that disappeared long ago. But since many games in this website still use them, I think an explanation can be helpful.

1981 PCs could come with two different graphic cards, mutually exclusive. MDA could only display text, which means only a few text adventures support it. CGA on the other hand was capable of graphics and became the first PC standard.



CGA cards allow resolutions as high as 320x200 with 4 simultaneous colors or 620x200 in B/W. This videocard is often criticized because of its lack of color variety. Only two palettes are available for the 320x200 modes: 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.

The came the Hercules in 1982. Developed outside IBM, it can show graphics up to 720x350, but only in B/W. 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 graphics appeared in 1984. This videocards can show graphics up to 640×350 in resolution and with 16 simultaneous colors. They're also CGA compatible.

MCGA was only available in some IBM PS/2 models from 1987. It has some 256 modes available and it's CGA compatible, but not EGA compatible.

The VGA videocards came in 1988 and close the gap between the PCs and what other 16-bit computers of the era could offer in terms of graphics. They have at least 256 Kb. RAM and can show graphics up to 800x600 and 256 colors. VGA is compatible with earlier display modes with the exception of the 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. Regular PCs can't access these modes.

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. /Tandycomputer.


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

PC games from the 1980s like this one are lots of fun. They were created to run in a wide variety of PC setups, you can tell from the different captures.

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 bankruptcy. 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 DOSBox ECE or DOSBox-X.

- 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 newer versions of Windows. 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.

 

Consider this an addendum. Here I'm going to talk about several more obscure graphic modes that are only available through emulation on present-day PCs.

First, there's the CGA Composite mode. Before I've mentioned how disappointing CGA videocards were to gamers, offering only 4 simultaneous colors. However, game programmers soon learned of a hardware trick to display 16 simultaneous colors. On the minus side, the resolution was then only 160x200. And not just that. In order to display these graphics, the CGA card needed a composite output and a NTSC monitor.

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


Regular CGA mode


CGA Composite mode

A you can see, we get more colors at the expense of resolution.

Many DOS games from the 1980s can show CGA Composite graphics, especially if they were developed in the USA. Notable cases are many PC Booter games and Sierra adventures using the AGI engine.

Before I also mentioned the Tandy 1000 and IBM PC jr. machines. These were PC compatible machines with a few extras that weren't inherited by newer PCs. They all came with CGA cards capable of some 16 color modes, and there are games that use them.

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 PC jr. 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.

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.

You can find more info about these display modes on the Wikipedia and Nerdy Pleasures websites. MobyGames also maintain several lists on games that support CGA Composite, IBM PC jr. and Tandy characteristics.

EDIT: I forgot to mention the Amstrad PC1512 graphic mode. The PC1512 was one of the first cheap PC clones in Europe and was quite successful. It came with a CGA card that could also use a 640×200 resolution with 16 colors. Why such a mode was included is a mystery to me, although it could have something to do with the GEM desktop that was offered as an alternative to DOS.

Only a handful of European games make use of this display mode, such as Frank Bruno's Boxing, Mortville Manor or Maupiti Island.


Mortville Manor

You can find more about this display mode in this VOGONS thread.

 

It seems that there was another cga mode, which few people supported, it was used, for example, in the popcorn game (the difference is in the presence of red)

 

@Михаил_128к, that's not a mode (like in "RGB mode" or "Composite mode"), that's a palete. And not an unusual one at that - just the palette #3.
Here is a nice example I used to illustrate - a game that features all the three color CGA palettes + Hi-Res monocrome + Hercules + Amstrad PC1512: Les Ripoux (1987, DOS, скриншоты)

 

To be fair, I didn't know about that third CGA palette. Most CGA games I know use the second one, cyan, magenta, black and white.

EDIT: Here's a game using the CGA first palette, it's Emilio Butragueño ¡Fútbol!



Personally, I prefer it over the second one, I can't stand cyan and magenta.