When the Genesis was released in 1988, very few arcade boards at the time was able to produce the same video resolution (320x224). There are a lot of systems with a much better hardware but using a lower resolution, like Namco System 2 (288x224), Konami TMNT2 Based hardware (288x244) or Neogeo (304x224). The same could be said about the home consoles (SNES = 256x224).
Is there any technical reason for that?
TV overscan. 320 pixels is NOT what you could see - overscan meant that of the 320 pixels, you might see 304 down to as little as 288 pixels, but it varied from TV to TV, so they allowed more with guidelines on where to keep the action and stats so that nearly all TVs showed all the "important" pixels. That same TV frame on 256 wide modes means you might see as little as 228 pixels - the same rules about overscan apply to all consoles. It's only with the advent of digital TV circuits and especially digital displays that overscan has dropped to almost nothing. You STILL lose several pixels on either side of the display on most TVs, even modern LCDs. If you know how to get into the service mode of the TV, you can adjust the overscan to a certain amount - perhaps even eliminate it altogether depending on the TV.Quote:
Originally Posted by tisurame
Hum. I don't think the overscan area eat that many pixels, and the overscan is much less prominent on the horizontal resolution. On the vertical resolution there are a lot of pixels hidden by the overscan area, but since Genesis games use x224 (and not x240), it's also a negligible problem.
For example, most PSOne games use 320x240. Then, a SDTV will only display 224 (vertical) pixels.
Overscan doesn't seem to be a valid reason. The SEGA arcade boards since the mid 80's started to use 320 pixels - so, I'm not sure why others companies did not do the same.
No doubt, with the resolution increase there is a huge impact in the viewable area of the game, and since most games are horizontal oriented, it makes much more sense to increase the horizontal resolution to 320 pixels and with that achieve a near perfect 4:3 aspect ratio. You can see a lot of arcade boards with multiple CPUs, sound chips and other crazy stuff - but using a resolution less than 320. So, I was wondering why.
Overscan wasn't the reason. There was a giant border around all games (without exception) to account for that. But it would eat up a few pixels. I know that if you draw a perfect circle in a game that runs at 256x224 it will be horizontally stretched when viewed on a TV screen. This is why many SNES games look "fat". Compare Earthworm Jim, for example. Many, many SNES games are guilty of this. However if you draw a perfect circle in a game that has a 320x224 resolution, then you will get a very nearly perfect circle on the TV screen. 320x224 is closer to a square pixel version of a TV's aspect ratio. 256x224 does not use square pixels and that is taken into account during design as often as it should have been. Also, many games that were designed for 256-wide screens on other systems were squished inside a 320-wide screen ont he Genesis and given a status bar to make up for the extra screen real-estate it afforded like Devil's Crush/Dragon's Fury and Zombies ate my Neighbors. Also Blackthorne.
Uh - no. 320x224 is NOT square, it's almost perfectly NTSC PAR (10:11). It's CLOSER to square than 256x224, but not so much that you can ignore the aspect ratio. It was as I said - overscan reduced the usable space on the screen, meaning you needed a slighter higher horizontal resolution to do more detailed images.Quote:
Originally Posted by Joe Redifer
Yeah, that's pretty much exactly what I said:Quote:
Originally Posted by Chilly Willy
320 x 240 would be square, but the 320x224 area is not being stretched to the edges of the screen, so in development it can basically be treated as square pixels without much worry of distortion when the image is displayed on a TV screen. But your overscan explanation is common sense. The higher resolution, the more detailed the images. But it doesn't answer tisurame's original question. Lots of other game systems of the time which also worked inside the same overscan area predominantly used a lower resolution. Even the Neo Geo you can see a bit of black pillarboxing on many NTSC sets (though very, very slight). Overscan was not the reason for the 320 mode otherwise all systems would have 320. Genesis had a 256 mode as well.Quote:
Originally Posted by Joe Redifer
I will accept that overscan IS the reason for the 224 instead of 240.
The Genesis' 40 cell wide mode just adds another column of 8x8 cells. I assumed this didn't affect the sprite pixel aspect ratios at all unless the developer wanted it to.
Lots of old computers had a predominant resolution of 320 x 200, including the C128, Amiga, Atari ST, Apple IIgs, Tandy CoCo 3, and PC VGA in 256-color mode. I guess that was probably different in Europe.
Basically, running a game in 320 mode does not mean you take a hit in the sprites nor do you gain anything from the sprites by running in 256 mode. The Genesis accommodates for the increase in resolution in 320 mode. As for their aspect ratios of course it changed. One is 256 pixels across and the other 320 pixels across all displayed in the same TV space.Quote:
Originally Posted by sheath
Um, actually yes... though the other way. The sprite limits are increased in H40 (320) mode. On the other hand, H32 (256) mode lets you get away with less pixels, which can be useful when you're really tight on memory usage.Quote:
Originally Posted by Joe Redifer
What I was asking without asking is if the sprites' aspect ratio changes between 32 Columns and 40 Columns. I think I know the answer to that question though because I've seen people talking about sprites getting stretched and needing to be redrawn for 320 wide mode.
ALL pixels get stretched. The screen size remains the same, the pixel size change. Pretty much the same way as for different resolutions in computers.
Is the background color that goes outside of the normal game screen considered part of the horizontal resolution?
256 wide mode and 320 wide mode occupy the same space on the screen. All that changes is the width of the individual pixel. That means the in 320 wide mode, more pixels are visible and they are closer to square in aspect ratio. The "closer to square AR" is helpful with art, but not crucial as you can see from all the consoles that have 256 wide displays. The "more pixels are visible" is the REAL improvement since that means you can show more detail.
No, but it technically should. Anything that is not part of the horizontal blank range should be considered the active line and therefore contribute to the horizontal resolution. TECHNICALLY, most "320" wide display modes are closer to 340 to 360 wide with the extra pixels not addressable and automatically filled with the background color. Now you're getting into the nuts and bolts of the VDP, so it will vary on the exact console, and sometimes revisions of the console.Quote:
Originally Posted by sheath
At this point you should probably just ditch the concept of resolution and use frequencies, considering how TVs have absolutely no concept of pixels at all. The idea of pixels is imposed by whatever generates the signal, not the display.Quote:
Originally Posted by Chilly Willy
Or in this case, even the pixel width can change within a given scanline... (and technically those shouldn't be even considered pixels, but rather VDP clock cycles)Quote:
Originally Posted by Chilly Willy