15kHz arcade monitor question

[TheManuel]

I was reading through the arcade monitor info on http://www.ultimarc.com/monfaq.html and learned that, for games with with less than 240 lines of vertical resolution, MAME introduces black bars on top and bottom of the image to keep within the maximum vertical resolution limit.  Yet this is true to the original arcade game's graphics hardware.
So, if you have an arcade monitor setup with say, the ArcadeVGA and you are playing Street Fighter II (384x224) with top and bottom black borders, do you simply adjust the monitor's overscan to make the borders dissapear beyond the screen and get the correct 4:3 aspect ratio?
Or, is the aspect ratio already correct with the borders and the original arcades showed this borders?

Thanks.

[TheManuel]

Quick update:
I looked at pictures of original cabinets at www.klov.com and they don't show black borders on the screen.  If you have to hide the borders using overscan, this sounds like a pain in the ass for a multi-game setup since you probably won't want this amount of overscan with other games.  Do you have to adjust the overscan back and forth as you switch games then?

[JoeB]

Another good example is Neo Geo games.

If you play a lot of games, you don't really notice this.  The reason being is the bazzle.  It takes a bit of realestate from the viewable screen.  If you stretch the game too much, it doesn't look right.

[wpcmame]

Aspect ratio is a really tricky thing and it is not easy to get it correct.

It all depends on how many lines your monitor displays. If you have adjusted it so that 240 lines covers the entire monitor (vertically) you will get black borders when using 224 lines (regardless of what resolution you use)
If you want the correct aspect ratio for 224 line games you need to add borders at left/right as well.

The most exact way to add left/right borders is to alter the pixel clock but that is rather difficult.
An easier way is to increase the horizontal resolution (which is more or less the same thing as altering the pixel clock but you will need to manually select the correct resoultion). So for 224 line games you increase the horizontal resolution with 240/224=7.1% (i.e. use 411 horizontal pixels for 384x224 games). The vertical resolution doesn't matter. Select one that got the correct refreshrate.

Note that if you have adjusted your monitor for 256 lines you will get black borders also for games with 240 lines and will need to adjust the horizontal resolution for these games as well using the same formula.

(Ofcourse, none of this is needed if your monitor automatically adjust the picture to cover the entire screen)