But, having said that, isn't it a bit curious the chosen resolution for CGA was 320x200 when this in fact could not be displayed correctly on a standard monitor (unless you had black bars that is).

320x200* can easily be displayed on a standard 4:3 CRT monitor. Think about how a CRT works: it draws horizontal lines from top to bottom and repeats. The number of lines can change without affecting the aspect ratio (less lines -> bigger gaps between lines and more lines -> the lines blur together). The horizontal resolution defines how the electron beam intensity changes within one line. 320 pixels means it can change 320 times per line. A video mode like 2000x400 can be displayed on a 4:3 CRT without black bars: there are 400 horizontal lines and each line can change intensity 2000 times.

*200 lines is too little for CRTs - the video controller actually generates two video lines from one "line" in memory. There are also hidden lines which don't take up any memory, but which are generated to allow the CRT to return the beam from the bottom right to the top left position.

But, having said that, isn't it a bit curious the chosen resolution for CGA was 320x200 when this in fact could not be displayed correctly on a standard monitor (unless you had black bars that is).

Certain reasons could be thought of:
- CGA needed to work with NTSC TVs (that requires fixed horizontal and vertical and dot clock frequencies)
- 80x25 text mode desired (graphics mode differing from that or 9x8 fonts would have required even more complex cirquits and the CGA card is damn huge already)
- Video RAM limitation (CGA has 16kb, 320x240 wouldn't fit in there)

wd wrote:

Read again what hal posted, that's exactly where the non-square pixels come into play (320x200 cga DID fill the full 3:2 screen without black bars).

pipa wrote:

320x200* can easily be displayed on a standard 4:3 CRT monitor.

We might be misunderstanding each other. I know CRTs could display the picture. What I'm wondering is, what did it look like. Did it look like my first or my second screenshot. If I understood all the technical stuff correctly it would have looked like the second screenshot, right?

Some games were designed with square-pixel ratios in mind (like no correction when drawing circles), which looked/looks not-full […]
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Some games were designed with square-pixel ratios in mind (like no correction
when drawing circles), which looked/looks not-fully-correct by times if it is
noticeable at all. Most games were simply written to "look nice" on the
standard 320x200 for a 3:2 screen.

What's a 3:2 screen? I think I'm still not grasping the (non-)square-pixel concept. Does anyone know a good resource where I could read up on that?

*200 lines is too little for CRTs - the video controller actually generates two video lines from one "line" in memory.

That is true for VGA and for some "Super EGA" cards. CGA and IBM EGA didn't do line doubling.

What's a 3:2 screen?

Replace all 3:2 with 4:3, a regular monitor.
On a 4:3 screen using a resolution of 640x480 you get square pixels, simply
because 4:3==1,333==640:480==1024:768 etc.
When you display a 320x200 mode on such a screen, the pixels are not square
because 320:200==1,6 (pixels are then a bit higher than wide).

wd wrote:

Replace all 3:2 with 4:3, a regular monitor. On a 4:3 screen using a resolution of 640x480 you get square pixels, simply because […]
Show full quote

What's a 3:2 screen?

Replace all 3:2 with 4:3, a regular monitor.
On a 4:3 screen using a resolution of 640x480 you get square pixels, simply
because 4:3==1,333==640:480==1024:768 etc.
When you display a 320x200 mode on such a screen, the pixels are not square
because 320:200==1,6 (pixels are then a bit higher than wide).

Okay, so every pixel is vertically stretched resulting in a stretched overall picture. Just like the second screenshot, right?

Yes, minus scaling artifacts.

h-a-l-9000 wrote:

Yes, minus scaling artifacts.

Thanks, I think I got it now 😉

Having said that, the video captures and (internal) screenshots are in 320x200 (or a multitude of that) and the game itself is too if aspect=false. Now, I get the game was programmed that way and is also processed by the graphics card like that. But, if no one actually saw it like that, how is this an accurate representation of how thine gs were back then. Okay, the aspect=true settings makes more sense now knowing this as it does indeed "fix" the aspect ratio to reflect how it really was.

Also, does anyone know of games that were programmed in a way that this stretch actually resulted in a picture as intended (by having a horizontally stretched look in 320x200).

Because, imho, from an artistic point of view its weird to program a game to look perfect in actual 320x200 only to then have it distorted/stretched by the display hardware. Like, in my example, the lives displayed on the right lower side or pac-man and the ghosts in general. They all look wrong in the stretched version. If I had been a coder back then I'd have tried to find a way to assure it looked best on a 4:3 display.

http://www.mobygames.com/game/dos/star-wars-x … eShotId,146351/
look at corner radars

robertmo wrote:

http://www.mobygames.com/game/dos/star-wars-x … eShotId,146351/
look at corner radars

Mh, thanks, this does indeed show such an approach. I'm curious though why a VGA game has a native resolution of 640x400.

It also means those screenshots at MobyGames are wrong in the sense that, again, they do not represent how the game actually looked when played. This is quite complex indeed. I stumbled across all these problems because I need to take captures and screenshots for a database project (NO, not abandonware, a completely legal project). One of the aims is accuracy but it seems very hard to decide what's accurate here. The resolution the game was programmed in or the way it was actually shown on a screen.

I'm curious though why a VGA game has a native resolution of 640x400.

vga is usually 640x480x4 (square pixels) or 320x200x8.

Having said that, the video captures and (internal) screenshots are in 320x200 (or a multitude of that) and the game itself is too if aspect=false. Now, I get the game was programmed that way and is also processed by the graphics card like that. But, if no one actually saw it like that, how is this an accurate representation of how thine gs were back then. Okay, the aspect=true settings makes more sense now knowing this as it does indeed "fix" the aspect ratio to reflect how it really was.

The easy fix is to have your video player treat it as 4:3 video. Many players have options to force a certain aspect ratio on playback. If AVI supported a standard way to define the aspect ratio, playback would automatically be correct. For example, digital television in Europe is 720x576 which is then displayed at 4:3 or 16:9 depending on aspect ratio data in the bitstream.

ripa wrote:

Having said that, the video captures and (internal) screenshots are in 320x200 (or a multitude of that) and the game itself is too if aspect=false. Now, I get the game was programmed that way and is also processed by the graphics card like that. But, if no one actually saw it like that, how is this an accurate representation of how thine gs were back then. Okay, the aspect=true settings makes more sense now knowing this as it does indeed "fix" the aspect ratio to reflect how it really was.

The easy fix is to have your video player treat it as 4:3 video. Many players have options to force a certain aspect ratio on playback. If AVI supported a standard way to define the aspect ratio, playback would automatically be correct. For example, digital television in Europe is 720x576 which is then displayed at 4:3 or 16:9 depending on aspect ratio data in the bitstream.

This would only fix the videos though and only if the person playing them has an actual file (no youtube upload etc) and knows about this.

What setting are you guys playing CGA (or 8-bit vga, thanks wd) games on then? One that has the stretched view as it was back then or one using the actual game resolution? I'm still undecided what's more accurate in terms of historical preservation.

hydr0x wrote:

But, having said that, isn't it a bit curious the chosen resolution for CGA was 320x200 when this in fact could not be displayed correctly on a standard monitor (unless you had black bars that is). Does anyone know the reasoning behind this? And how it looked when hooked up to a TV instead?

The line count 200 was fixed by the NTSC TV system's number of lines (a maximum of 243 visible lines, but those near the border tended to be distorted and/or hidden by overscan, so the chose 200). The number of dots, 320, probably has to do with the desire to fill 16 kilobytes of memory (which the CGA had) without too much waste, or with the dot clock which was derived from the NTSC color carrier frequency.

hydr0x wrote:

Also, did any developers try to adjust for this kind of vertical stretching by reversing the processing? As in, storing a squished picture in 320x200 that would look right when stretched to 4:3? Somewhat like anamorphic DVDs.

Yes. E.g. look at the circles in Ultima VI's inventory. They are not circular in square pixels.

TeaRex wrote:

Yes. E.g. look at the circles in Ultima VI's inventory. They are not circular in square pixels.

they are 😉
http://www.mobygames.com/game/dos/ultima-vi-t … meShotId,57145/

http://www.mobygames.com/game/dos/dune-ii-the … meShotId,61890/
Oval vs. circle are, of course, the easiest cases to spot. 😀

Mobygames stores the images at original 320x200 and stretches them to 640x400... would be nice if they offered 4:3 stretch, optionally.

ripsaw8080 wrote:

Mobygames stores the images at original 320x200 and stretches them to 640x400... would be nice if they offered 4:3 stretch, optionally.

It is enough to switch your desktop resolution for the moment of watching to the resolution with less lines: your number of lines divided by 1,2.

so if you have 1280x960 -> 960/1,2 -> 1280x800

if you have 1280x800 -> 800/1,2 -> 1280x667 (you can add this resolutins with nvidia control pannel)

😀

robertmo wrote:

TeaRex wrote:

Yes. E.g. look at the circles in Ultima VI's inventory. They are not circular in square pixels.

they are 😉
http://www.mobygames.com/game/dos/ultima-vi-t … meShotId,57145/

Ok I take it back, seems like I start getting 320x200 eyes. Next step after square eyes. 😁

well at least I started a somewhat interesting discussion with my initial problems 😉 Does anyone know whether someone has already attempted to create a list of games counter-acting this stretch?

All important games do it.

It is just some low cost games that didn't do it.