20
SOME BASICS OF BASIC
n First steps
The first things that a beginner learns to do are to list a pro-
gram and to print a character string. Certainly these are the
easiest operations one can do, but even they may depend on
what computer you have. In Microsoft BASIC, we can list all
the steps in a program by entering LIST. This lists them on the
CRT screen; if we want to print them on a printer, we prefix the
command with an L (enter LLIST).
The Microsoft BASIC command for outputting information is
PRINT. Like the LIST command, this displays the information
on the CRT screen so we have to add an L (-+ LPRINT) if we
want to use the printer. Just put whatever you want to print be-
tween quotes and after LPRINT (anything enclosed in quotes is
called a character string). For example, we would use LPRINT
“Hello!” to output “Hello!” to the printer. We’ll see later how to
LPRINT more than just character strings.
We started with Microsoft BASIC because it is the most wide-
ly used version of BASIC. The programs in this manual are
written in Microsoft BASIC so they should run on most com-
puters. But if strange things happen when you try to run a pro-
gram, check the BASIC manual that came with your computer.
Let’s consider Apple 11 computers for a minute. These
popular computers use their own brand of BASIC. To use an
Apple II, enter the following-
PR#l PR#l
LIST PRINT "Hello!"
PR#O PR#O
The PR#l tells the Apple to send everything to the printer,
the LIST or PRINT command sends it, and the PR#O returns
output to the screen.
Now that we know how to address the printer, let’s try listing
a BASIC program. We will load a program into memory ready
to program printer operation - just as soon as we learn a little
bit about the ASCII codes.