It's not like your old DOS scan guns where there was a definite number of characters (rows and columns) that could fit on the screen. Instead, it runs Windows Mobile or Windows CE, which has a graphical interface (like your PC). It comes preloaded with terminal software from Wavelink to connect to your AS400, and you can set how large or small you want the font to be in that terminal emulator. So the answer is, the "lines per screen" and "characters per line" can pretty much be as many or as few as you want. It's a trade-off between how much you can fit on the screen and how well you can read it if you were to choose a font size that is too small.
I will say that Wavelink does a good job with this emulator at allowing you to scroll around the screen though. If there is anything that won't fit on the screen, you can just press the Ctrl key and then use the up/down/left/right arrows to page around the screen.
Thanks,
Brad Radaker
Radicomm, Inc. (makers of QuickTalk, push-to-talk for the MC9090)
www.radicomm.com