INTRODUCTION

Computers have three basic abilities: they can calculate, make decision, and communicate. Calculation is probably the easiest to program. Most of the rules of mathematics are familiar for us. Decision making is not too difficult, since the rules of logic are relatively few, even if you don't know them too well yet.

Communication is the most complex, because it involves the least exacting set of rules. This is not an oversight in the design of computers.

OUTPUT TO THE TV

The simples form of output in BASIC is the PRINT statement. PRINT uses the TV screen as the output device, and your eyes are the input device because they use the information on the screen.

When PRINTing on the screen, your main objective is to format information on the screen so it's easy to read. You should try to think like a graphic artist, using colors, placement of letters, capital and lower case letters, as well as graphics to best communicate the information. Remember, no matter how smart your program, you want to be able to undestand what the results mean to you.

The PRINT statement uses certain character codes as "commands" to the cursor. The CRSR key doesn't actually display anything, it just makes the cursor change position. Other commands change colors, clear the screen, and insert or delete spaces. The RETURN key has a character code number (CHR$) of 13. A complete table of these codes is contained in Appendix C.

There are two functions in the BASIC language that work with the PRINT statement. TAB positions the cursor on the given position from the left edge of the screen, SPC moves the cursor right a given number of spaces from the current position.

Punctuation marks in the PRINT statement serve to separate and format information. The semicolon (;) separates two items without any spaces in between. If it is the last thing on a line, the cursor remains after the last thing PRINTed instead of going down to the next line. It suppresses