Setting a 254 resolution?

[LordBarker]

Hi all.

This is specifically related to Retro Pi and Pi2SCART, but suspect it applies across the board.

I'm getting a lovely 240p image on my PVM with these timings:320 1 16 30 34 240 1 2 3 22 0 0 0 60 0 6400000 1

However if I aim for 1600 x 254 for NBA Jam for example (with the original arcade resolution being 400 x 254) I have to use the underscan button on monitor to get the whole image in due to the increased height, keeping it looking nice.

I assumed, wrongly, that I could just change the 240 number in the HDMI timings and all would be okay. This had no effect, and I'm just wondering if there is anyway I can alter anything to get the full image on screen without hitting the underscan button? I'm also wondering how Groovy Mame scales these Midway games on an arcade monitor/CRT etc? As it must be a similar principal.

Thanks as ever.

[lukilla]

The other day I was watching a video of some midway game on groovymame and it just defaults to 480i, afaik you can´t tweak height via timings.