Go Back   Forums > Abandonia.com > Troubleshooting > Tutorials
Memberlist Forum Rules Search Today's Posts Mark Forums Read
Search Forums:
Click here to use Advanced Search

Reply
 
Thread Tools Display Modes
Old 07-03-2017, 01:12 PM   #1
Neville
Super Freak

 
Join Date: Apr 2008
Location: Lerida, Spain
Posts: 152
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 05:51 PM.
Neville is offline                         Send a private message to Neville
Reply With Quote
Old 07-03-2017, 01:34 PM   #2
Neville
Super Freak

 
Join Date: Apr 2008
Location: Lerida, Spain
Posts: 152
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 05:55 PM.
Neville is offline                         Send a private message to Neville
Reply With Quote
Old 07-03-2017, 02:06 PM   #3
Neville
Super Freak

 
Join Date: Apr 2008
Location: Lerida, Spain
Posts: 152
Default

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 01:39 PM.
Neville is offline                         Send a private message to Neville
Reply With Quote
Old 09-07-2019, 05:45 PM   #4
JeffWiley
Lurker

 
Join Date: Jul 2019
Posts: 1
Default

Hi.,..If it has switches so it oculd be toggeled to CGA mode on startup, it would operate as a CGA, and there would be no differences unless the card is of lower quality and price.
However, if it's configured as VGA on startup, it might have some problems with certain CGA graphics modes.

pcb assembly

Last edited by JeffWiley; 22-08-2019 at 03:52 PM.
JeffWiley is offline                         Send a private message to JeffWiley
Reply With Quote
Old 13-07-2019, 05:01 PM   #5
Neville
Super Freak

 
Join Date: Apr 2008
Location: Lerida, Spain
Posts: 152
Default

Hadn't seen your message (Yahoo and certain boards don't like each other). Hope I didn't make you wait too much. I think you're talking about VGA compatibility with older modes? It's a bit messy. From I've learnt over time:

CGA can show text mode, but not as sharp as MDA.

Hercules can do CGA graphics, but only through a software emulator like UniCGA, and they will show in B/W, obviously.

EGA can do CGA.

MCGA can do CGA, but not EGA.

VGA can do all the above, except Hercules. Choosing Hercules mode under VGA will show CGA instead.

My first PC had a SVGA card, but I liked to try other graphic modes in games. Normally they would show without errors.

Last edited by Neville; 20-07-2019 at 02:02 PM.
Neville is offline                         Send a private message to Neville
Reply With Quote
Old 15-07-2019, 09:37 AM   #6
Smiling Spectre
10 GOSUB Abandonia
20 GOTO 10
 
Smiling Spectre's Avatar




 
Join Date: Mar 2009
Location: Cherkessk, Russian Federation
Posts: 1,714
Send a message via ICQ to Smiling Spectre Send a message via AIM to Smiling Spectre Send a message via MSN to Smiling Spectre
Default

You give the comparison just above, Neville, no?

CGA _mostly_ is good in higher modes, but sometimes gives off-colors, and composite modes not always works in real hardware.

EGA is mostly compatible with VGA/SVGA, but can give flickers in rare cases.

Tandy is incompatible with all this modes at all.

(It's from my experience working with VGA then SVGA displays, 20+ years ago. DOSBox more tricky with that, so while I can give more incompatibility examples, I am not totally sure they are the same for the real hardware).
__________________
Smiling Spectre is offline                         Send a private message to Smiling Spectre
Reply With Quote
Old 20-07-2019, 01:43 PM   #7
Neville
Super Freak

 
Join Date: Apr 2008
Location: Lerida, Spain
Posts: 152
Default

Yes, but I don't mind repeating myself. The introductory paragraphs are becoming a bit messy and JeffWiley could have missed the info he was looking for.

As per SVGA cards... yes, they have their faults as well. Not too long ago I learned that under DOSBox machine=cga can make certain older games look better than the default machine=svga_s3. Games like Bob Morane: Science Fiction I, Circus Games, Exterminator, Jr Pacman, etc.

In theory those games should work with any SVGA card, but... either someone cut corners when designing the S3 or the games use undocumented modes.

Also the S3 is not compatible with every game out there... In some versions of NASCAR Racing 2 and NASCAR: 1999 Edition show wrong colors. Luckily DOSBox now supports a few other SVGA cards.


Last edited by Neville; 20-07-2019 at 01:52 PM.
Neville is offline                         Send a private message to Neville
Reply With Quote
Old 21-07-2019, 11:25 PM   #8
Scatty
Treasure hunter
 
Scatty's Avatar

 
Join Date: Jan 2006
Location: Little big small world
Posts: 1,860
Default

Technically, my old originally 486-DX2 66 - later upgraded to Pentium 100 and some little known Chinese 8MB PCI graphics card - had a 1MB Cirrus Logic SVGA card before the upgrade, supported with all the required DOS drivers, which was 100% VGA. But it couldn't display Hercules mode properly, only a garbled messed up display if tried.


All other modes (except Tandy of course) were displaying no problem, even some more obscure ones like 640x200x16 (like what the WarWizard game on Abandonia would display natively on true old hardware, not in DosBox though).
640x220, 640x400 (Rise of the Robots for example), 600x350 etc. etc. in all colors from 4 to 256 / monochrome. Tested with one of the old Dos picture display programs, by converting pictures to various resolutions, I used to play around lot with that. The monitor played fine with it, it has max. supported resolution of 1024x768 and up to 24bit colors (16mio), but the Cirrus Logic card could only carry up to 256 colors in 1024x768 and the 16mio colors only in 640x400 and 640x480. Those are all SVGA modes anyway.



But Hercules mode, no way, not even transforming it to CGA resolution(s). Just throwing my 2 cents out there.

Last edited by Scatty; 21-07-2019 at 11:33 PM.
Scatty is offline                         Send a private message to Scatty
Reply With Quote
Old 22-07-2019, 05:45 PM   #9
Neville
Super Freak

 
Join Date: Apr 2008
Location: Lerida, Spain
Posts: 152
Default

Cirrus Logic were among the best SVGA cards in their day, and they should show Hercules (well, as CGA, as explained above). If you tell me the problem wasn't the monitor I'll have to believe you, naturally.

Oh, and 1024x768x256 was the highest mode for *any* SVGA card with 1 Mb. RAM. If you wanted more, you had to find more RAM for your card, and that wasn't easy nor cheap.

But for a real lousy experience with a SVGA card, try a Trident. My first one was one of those, and it often killed my monitor whenever it tried to access beyond 640x480 modes, especially under Windows 3.X.
Neville is offline                         Send a private message to Neville
Reply With Quote
Reply


Similar Threads
Thread Thread Starter Forum Replies Last Post
"Wolfenstien: The New Order" reveal trailer in Hercules Graphics (WIP) Expack2 Music, Art, Movies 6 24-05-2013 02:10 PM
Hercules/Ancient Greece/Trials DOS game Mordant Forgotten Games Bureau 5 02-02-2013 12:43 PM
Hercules [DISNEY] Oliwerko Rejected requests 7 26-07-2012 10:49 AM
Alt text display wackypanda Tech Corner 6 02-04-2011 01:12 PM
Display Adaptors Wade Tech Corner 7 18-08-2006 06:22 AM

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Forum Jump
 


The current time is 01:56 AM (GMT)

 
Powered by vBulletin® Version 3.7.1
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.