Instructions
Press the "Home" button on your PSP.
Scroll down to locate and select "Settings."
Choose one of the following screen sizes to adjust the appearance of your game:
"Fullscreen" changes the display to full screen, similar to your television. This adds small black borders to the top and bottom of the screen so that the emulator fits the 16x9 ratio.
"Original" is the default display for PlayStation games and will display the game at 320 x 240px.
"Normal" stretches (less than "zoom") and smooths out the display.
"Zoom" stretches the display so that the width is equal to the width of the screen size.