Mame Aspect Ratio

Hello fellas! I have a bit of a problem. I'm trying to keep Games like Street fighter 2, MK, etc full-screen/stretch but games like pac-man and centipede I want to keep them at the correct aspect ratio. I read somewhere that you can make separate mame.ini file for each game. If this true how do I do go about doing so. A step by step tutorial would help. I'm using the cmd line version of mame.

if you don't have a mame.ini, create one:

>mame -cc

Now open mame.ini, make sure inipath says ini.

Make sure readconfig and writeconfig are both set to 1.

Make any other changes you wish. Now save & exit mame.ini

Next, make sure that the subfolder ini exists, if not >md ini

Next, copy mame.ini to the ini folder.

Now you should be right to go. Just make sure you start each game from the command line, not from mame's inbuilt menu. The inbuilt menu will corrupt ini files after you play your second game.