Epson MX-80 User Manual page 43

Introduction to Graphics
Putting Dump To Work
Well, the above was a lot of work just to get a program listing. We can do that
with a simple LLIST. Let's put our dump program to a real test.
Add these program lines. They fill the screen with random characters of all sorts,
then our Dump program sends t h e r e t o the Printer:
1 CLS
1 0 FOR N = 1 TO 2 0 0
2 0 R = R N D ( 1 5 9) + 3 2
3 0 L = R N D ( 1 0 2 4 ) - 1
4 0 P R I N T @ L , C H R $ ( R ) ;
5 0 NEXT N
then RUN.
Amazing. Quite a display, including graphics characters we've probably never used
before. Since this program's purpose is to just put 200 arbitrary characters at
arbitrary locations, some characters may get replaced by others. No matter. The
proof is in the dump.
Check the finished print-out against the screen to be satisfied that all this is true.
Once done, we can have confidence in our dump program.
Yep! It is as represented. The print-out seems a mite wide and a bit short,
compared to what we see on the screen. (Picky Picky!) But it's true. The reason is
that the "aspect ratios" are not the same.
Aspect Ratio?
Yes. In TV engineering parlance, that's the ratio of the picture's width to its
height. The perfect TV picture is one and one-half times as wide as it is tall. It's
aspect ratio is 3:2.
With the Printer in the normal 80 CPL mode, our printout looks like maybe its
aspect ratio is about 2:1. Wonder how we could make our screen dumps look
more like the screen? Ponder that one. How would YOU solve it?
' P R I N T 2 0 0 CHARACTERS ON SCREEN
'RANDOM # TO 1 5 9 BUT JUMP UP 3 2
' 1 0 2 4 SCREEN LOCATIONS, INCLUDING 0
' P R I N T THE RANDOM CHARACTER AT L
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