Talk:Enhanced Graphics Adapter

message: The page previously said "Introduced in 1984 by Microsoft [sic]." I'm assuming this was just a mistake, and have changed it to IBM. I don't recall Microsoft having anything to do with display hardware (although they've had more hardware products than many people thing).
If I'm wrong about this, please revert the change and leave a note here. Dpbsmith 15:26, 10 Jan 2004 (UTC)
replies: text: I figured this was a good topic for Google Groups. Joel  talks about his woes with his IBM card in December, 1984 in the first message mentioning either "Enhanced Graphics Adapter" or "EGA." He discusses required BIOS dates of October 1982.  Further details in this thread discuss an alternate card, the Princeton SR-12, in addition to some workaround information for the memory problem Joel encountered. Based on those early mentions, I'd say IBM did it. -- Ke4roh 15:56, 10 Jan 2004 (UTC)
thread_title: The page previously said 

message: Currently the article states "EGA also included full 16-colour versions of the CGA 640×200 and 320×200 graphics modes; only the 16 CGA/RGBI colours are available in these modes." However, I'm quite sure the pseudo 64 color mode was also supported at 320x200. Only one game used this to its advantage; Ivan Ironman's Off Road. The mode was called "EGA64" in it.
: Oooh!  Pseudo 64 colour mode?  Any idea how this was achieved?  The EGA has registers I believe that allow for very fast switching from one of four palettes.  This could perhaps have been used to switch the palette during display time such that all four palettes were displayed in a single frame, resulting in the EGA's full 64 colour palette being displayed.  Perhaps this was the trick?  Fast pallette switching has often been used to this effect, think 'copper' bars. -- Funkymonkey
:It'd be nice if someone could root out a screenshot or any other info on this, all I've found with a quick google is an abandonware version for download (which I *may* try out, still having an AT with an old ISA VGA adaptor squirreled away somewhere deep in a cupboard - it may show up what's going on if it's got any command line switches which allow you to force the display mode)... Somewhere out on the interweb must have a working EGA PC and a copy of the game to figure out what's going on here. The best I can estimate at are several possibilities --- 1, it uses fancy hardware tricks (as found on enough other computers) to force the hardware to change the palette against spec, and also maybe to perform palette switching (though even the VGA screenshots show a game screen remarkably similar to my Atari version, which is a solid 16 colour (from 512) game) in 320x200 mode... 2, it does the LucasArts trick of using 640x200 mode and dithering alternate pixels (ick)... 3, colour flickering? (as seen on Sega GG/MD)... 4, as the graphics used in the game are quite small and limited-motion, it may have just used 640x350 as-is, with higher rez trucks and high res or pixel doubled backgrounds, and varied the 16 colour palette within-spec (or used extra tricks)... 5, it set 640x350 and displayed all graphics doubled for an effective 320x175 rez, with 16 custom colours and again maybe tricks... 6, it set a custom mode of the hardware, using 640x350 as a basis but reducing vertical rez to 240 or less and doubling horizontally (i've seen demos that supposedly run on stock EGA hardware and can give upto 640x700 rez in 64 colours, so reducing the resolution instead probably wouldn't have been too difficult - or alternately increasing it to 400 then doubling everything). So yeah. Complicated. Needs actual game experience to figure out. 82.46.180.56 (talk) 18:10, 30 March 2008 (UTC)
replies: text:  Not sure if this is the same thing or not, but I remember some of the later LucasArts adventure games (Monkey Island 2, Fate of Atlantis) claimed to require VGA, but did actually run on EGA cards: the way it worked was to run in 640x200 mode, with each 320x200 logical pixel using two actual EGA pixels, i.e. in effect a rather crude kind of dithering to give the impression of displaying more than 16 colors.  It was kind of hideous, though, and pretty slow at times, which is probably why they never documented the feature! 81.86.133.45 (talk) 21:36, 10 February 2008 (UTC)
replies: text: It wasn't undocumented. Indiana Jones and the Fate of Atlantis allowed you to enter a switch to choose the display mode, and there was an option for EGA. It produced a 320x200 image that was stretched to 640x200. It was hideously ugly, and it was obvious that each pixel was vertically doubled. DOSGuy (talk) 21:46, 10 February 2008 (UTC)

text: The EGA card offers a free programmable mapping of the available color numbers in a mode to any of the 64 monitor colors in any mode, even in the low-res graphics mode with CGA resolution. As every color is individually programmable, there are not just 4 palettes, as Funkeymonkey suggests. As the hardware design of the EGA is that the image generation circuits output 4-bit-codes (and a blanking bit) for the image, and a totally separate circuit (called the "Attribute Controller") translates these 4-bit-codes to 6-bit-codes, the availability of this translation is not connected to the kind of video mode used. Still, the fact that real-time palette changing was used for effects as the copper bars is true. Of course, if the 200 lines graphics modes are used in conjunction with a CGA monitor that does not support the 350 lines mode, only 16 colors are available due to monitor limitations. 89.15.60.144 (talk) 17:36, 9 September 2011 (UTC)

text: In fact, the article also states the real reason for the non-availability of 64 colors in the low-res graphics modes. It is in fact not a limitation of the graphics cards, but of the monitor, as the original EGA monitor, the IBM 5154 falls back to a CGA compatibility mode when CGA frequencies are present, as it does not detect whether the two extra pins used for the 64 EGA colors are driven by the card (as an EGA card would do) or grounded respectively floating (as a CGA card would do). 89.15.60.144 (talk) 17:49, 9 September 2011 (UTC)
replies: text:  Probably nobody cares anymore but Ironman’s Off Road do support the 64-color palette in 320x200 (still 16 different colors on screen at the same time) - on any standard EGA and without using real-time palette changes or any other trick. The game mentions that it is possible to use this mode only with “switchable 64-color monitors”. That means that standard EGA monitors don’t understand the mode and use RGBI anyway. However, there were plenty of universal monitors supporting multiple modes for different computer platforms (digital, analog...). These monitors usually had a panel with switches for color settings so you could easily force them to use 64-color RRGGBB even with 200-line modes. Today, I finally saw it in person and it looked almost like the VGA version. - swarm@quick.cz, 2018  — Preceding unsigned comment added by 94.112.110.104 (talk) 20:05, 7 October 2018 (UTC)
thread_title: Currently the article

message: Should we say that EGA is the one which introduces "character generator" for text mode? Where you can modify text-mode character fonts instead of using the hardcoded BIOS ones only...  -- FourBlades 20:11, 12 August 2006 (UTC)
thread_title: Should we say that EGA

message: Some sources claim that EGA doesn't include MC6845 controller (this article and the book "Programmer's Problem Solver for the IBM PC, XT & AT" by Robert Jourdain). Can anyone confirm that?
--Anton Khorev 11:14, 24 October 2006 (UTC)
replies: text: The 640x350 mode uses 28000 bytes of contiguous memory, but the MC6845 can only address 16384 bytes, so clearly it can't be used in that mode. Of course this doesn't completely rule out the possibility that EGA cards had MC6845 for other modes, but that doesn't seem very likely. --Derlay 23:40, 16 June 2007 (UTC)

text: The EGA card does not use the 6845 video controller, but a chip designed by IBM that is partly compatible (to make page flipping and cursor positioning on the register level CGA compatible). The timing registers of the EGA card are not compatible to the CGA card, and, if I remember correctly, protected by a software controlled write lock (I might be wrong about that with the write lock existing only on VGA cards). The most pressing issue with the 6845 is the line counter which is limited to 7 bits. While this is clearly enough for text modes, in graphics modes, the consequence is that tricky ways of using the character row counter for high address bits have to be used to support more than 128 scan lines, which results in a banked video memory layout. In fact, the CGA has two banks and the Hercules card has 4 banks of 16 Kilobytes each in graphics mode to circument the line counter limitation. The EGA chip extended the line counter to 9 bits to avoid the issue, it also extended the address counter from 14 bits to 16 bits (that's the limit Derlay mentions). -- 89.15.60.144 (talk) 17:42, 9 September 2011 (UTC)
thread_title:  MC6845 

message: Please, give a quote from Scott Mueller (BTW user:Wtshymanski used an incorrect spelling). By what had EGA supplanted, and when exactly? VGA originally was intended as a video adapter for PS/2, not for various PCs. Incnis Mrsi (talk) 14:54, 7 September 2011 (UTC)
replies: text: I don't have the Mu(e)ller book handy now, but the EGA was withdrawn from marketing by IBM fairly quickly, so the IBM EGA was certainly obsolete by 1987. 3rd party EGA boards were available after that, I'm sure, but  the leading edge had clearly gone to VGA and fairly soon you couldn't give away an EGA board or monitor. --Wtshymanski (talk) 16:53, 7 September 2011 (UTC)
replies: text:  What means "give away an EGA… monitor"? This was a relatively expensive device at the time, and the whole world is not only North America, Europe and Japan there people were rich enough to spend money on continuous upgrades. Incnis Mrsi (talk) 16:20, 8 September 2011 (UTC)
replies: text:  It's an English figure of speech. It means that even if you offered the ownership of an EGA monitor or adapater to someone without exchange of money, that no-one would take it because it was worthless. --Wtshymanski (talk) 18:14, 8 September 2011 (UTC)
thread_title:  So named "obsolescence of EGA" 

message: You say that the EGA's palette has 64 colors, but that's wrong. The palette is the set of colors it's currently using, not the larger set that you choose colors from. If you had a palette with 16 differently-colored blobs of paint on it, and a box containing 64 different bottles of paint, would you say that your palette has 64 colors? No? Then don't do that with computer palettes.  — Preceding unsigned comment added by 24.192.185.6 (talk) 13:22, 14 October 2016 (UTC)
thread_title:  Palette doesn't mean what you think it means 

message: I got new three example of EGA color palette. I got:
 The three examples of EGA color palette
Default  	0x0	0x1	0x2	0x3	0x4	0x5	0x6	0x7	0x8	0x9	0xA	0xB	0xC	0xD	0xE	0xF
Example 1	0x0	0x1	0x2	0x3	0x4	0x5	0x6	0x7	0x8	0x9	0xA	0xB	0xC	0xD	0xE	0xF
Example 2	0x0	0x1	0x2	0x3	0x4	0x5	0x6	0x7	0x8	0x9	0xA	0xB	0xC	0xD	0xE	0xF
Example 3	0x0	0x1	0x2	0x3	0x4	0x5	0x6	0x7	0x8	0x9	0xA	0xB	0xC	0xD	0xE	0xF
— Preceding comment signature by an anonymous user: 2403:6200:8937:E50B:8857:14E9:8868:3B30 (talk) 05:23, 19 April 2019 (UTC)
thread_title:  Three examples of EGA color palette 

message: EGA provided more features than a simple increase in colors and resolution. It provided new features that allowed limited screen scrolling for instance, which was instrumental in the development of smooth scrolling videogames such as Commander Keen. There were other features which were historically significant, and these need to be added.Gravislizard (talk) 02:10, 16 August 2020 (UTC)
replies: text: Added mention to these features on the article, referencing the manual 4throck (talk) 12:01, 11 June 2023 (UTC)
thread_title:  Hardware enhancements 

message: This section contains the following sentence, which was introduced here:
The "as well as two monochrome modes at higher resolutions" part is problematic. Higher than what? A normal reading would suggest two modes higher than 640x350, but that is not true. EGA could not do that. It is true that one of the special and rarely-used MDA monitor-compatible modes (which required DIP switch-setting on the card) was technically slightly higher, at 720x350, but this was a text mode, and insofar as it had pixels, they were not all-points addressable. The second MDA-compatible monochrome mode was technically 640x350, but again it was a non-APA text mode. (The difference between these was the use of either a 9x14 or an 8x14 text character cell matrix in 80x25-character text mode.) So these are clearly not two monochrome modes at higher pixel resolutions, but that's what a first reading of that sentence would suggest to someone unfamiliar with the topic. ReadOnlyAccount (talk) 14:41, 18 October 2023 (UTC)
thread_title:  Capabilities