Atari 400 User Manual page 170

When you are using BASIC, something unusual
happens if you don't use quotation marks
around letters you want displayed. Type
PRINT ATARI
without using quotation marks. Then press RE-
TURN . The computer does not display ATARI; it
displays a zero.
SCREEN 8
If you do not enclose letters in quotation marks
following PRINT. the computer assumes you are
using the letters to represent a number, and the
computer prints that number.
Letters used this way in BASIC are called numer-
ic variables. The letters represent the numbers
you assign to them (such as X
=
3). When you
assign no value to a letter or word, the com-
puter reads its value as zero. Since you assigned
no value to ATARI, the computer displayed a
zero.
This concludes our short trip into Atari BASIC. If
you're interested in learning to program your
computer yourself. you 'll be amazed at the vari-
ety of tasks (both simple and complex) that you
can program your computer to perform.
168