Post subject: 320x240 and 320x200 resolutions for DOS games Posted: Tue Jun 11, 2013 10:25 pm

For the last few weeks I have been busy with MS-DOS games and DOSBox. With the standard DOSBox setting all (at least the ones tested) games are in 320x200 resolution and when looking closely that seems to be the correct resolution for most of the games. For instance with a 320x200 resolution 'Murphy' from 'Sapaplex' is round while with a 320x240 resolution its more of an oval. So 320x200 is the correct resolution? uhmm.. no..
I just booted the hardware I played games on like Supaplex back in the days and found out I (probably) always played with a 'wrong' resolution. The games are in a 4:3 (320x240) resolution and doesn't show black borders on top or bottom.
When I look further at games released by publishers like GOG.com and Steam they all scale them (the DOS games released with DOSBox) up to a 4:3 resolution.
So, why are most (if not all?) DOS games released in a 320x200 resolution instead of the then popular 4:3 screen resolution?

Post subject: Re: 320x240 and 320x200 resolutions for DOS games Posted: Tue Jun 11, 2013 11:37 pm

320x200 tv's/monitors were more common in the 70's.
http://en.wikipedia.org/wiki/Computer_display_standard

Post subject: Re: 320x240 and 320x200 resolutions for DOS games Posted: Wed Jun 12, 2013 12:44 am

The MS-DOS games I played back in the days were not exactly from the 70's.. more from the 90's..
So that's 20 years difference, so why did they preserve that resolution while (as far as I remember) no one connected his/her PC to a TV? Everyone I know had a monitor connected to there PC with a 4:3 resolution.
The only items that can play games I have seen connected to TV's were dedicated game consoles (NES/SNES/PS1/etc.). Although.. when I think about it.. I own some video cards from the late 90's that have either a video connector or a s-video connector next to the VGA connector.

Post subject: Re: 320x240 and 320x200 resolutions for DOS games Posted: Wed Jun 12, 2013 1:02 am

320x200 is defined in CGA/EGA/VGA, 320x240 is only defined later in the VESA standard.

Post subject: Re: 320x240 and 320x200 resolutions for DOS games Posted: Wed Jun 12, 2013 5:05 am

yksoft1 has this almost right, it has to do with the hardware. Back in the DOS days there were a couple video modes that were common, MDA, EGA, CGA, Hercules and some special ones like AT&T's 640x400. Your monitor and graphics card were only able to display one or two resolutions and one or two text modes (usually 80x25 or 40x25).
Games had to be programmed to use a certain resolution based on what the hardware supported. CGA was 320x200 or 640x200. EGA was 640x350, but can also emulate CGA's resolutions. Hercules was 720x350, but also could emulate CGA. MDA was a text-only adapter, and was rarely used for games. 640x400 was the oddball as it was only used on a couple systems, but there were still quite a few programs that supported it. The most common system with 640x400 was the Olivetti M24AT&T PC-6300.
The reason for CGA being most popular is most systems supported it in one way or another, whether it be emulation while stretching or just outright fitting it on the screen.

Post subject: Re: 320x240 and 320x200 resolutions for DOS games Posted: Wed Jun 12, 2013 11:05 am

320x200x8 and 640x480x4 were the official modes.You could find out via a program called fractint what non standard modes were possible on your old hardware.

Post subject: Re: 320x240 and 320x200 resolutions for DOS games Posted: Wed Jun 12, 2013 10:38 pm

Please note that the physical screen size at these times had a 4:3 ratio, but not the MDA, CGA and EGA resolution, because screen pixels were not square shaped before VGA.

Post subject: Re: 320x240 and 320x200 resolutions for DOS games Posted: Thu Jun 13, 2013 4:54 pm

Ching: http://en.wikipedia.org/wiki/Mode_X 320x240 Surfaced when a undocumented Mode X display mode hack was coded for the VGA standard.
It's a neat trick that is much better than the typical 13h mode, you can see the list of advantages in that article already but in a nutshell, it allowed much faster scrolling routines and more pages for the frame buffer.
The official IBM & documented 13h mode (MODE 13 in QBASIC for example) just has 320x200 at 256 colors and no page flipping, meaning that you saw the pixels being drawn in real time instead of drawing a frame in the 'back' and then switching to it once it had drawn, this made scrolling and rapid screen updates really jerky/tearing unless you masked it with tight code.
320x240 = square pixels with a 4:3 monitor (MODE X)
320x200 = square pixels with a 8:5 monitor
It was really up to the designers on what screen mode to use and draw art for (You couldn't really scale it in real time).
Also games that used mode X could also opt to use just/also 320x200 (MODE Y) in order to save some video RAM, a single frame in X is ~768Kbytes while in Y it would be ~640Kbytes, allowing the game to double buffering with lower VRAM configs.
Anyway, old VGA has tons of screen modes with different refresh rates, generally it was nothing to worry about with old CRTs, some Demoscene productions especially can easily confuse modern equipment since they change modes/sync between parts or even mid-frame!

Post subject: Re: 320x240 and 320x200 resolutions for DOS games Posted: Fri Jun 14, 2013 7:58 pm

The NEC PC-9800 series of computers also supported 640x400, and I also remember once that there was a certain video adaptor that had a 640x350 256 color mode.