Atari XL User Manual

56
20
30
40
The Ater! XL Handbook
PRINT "WHAT'S THE PASSWORD";:
INPUT
PW$
IF PW$ <> "BEANS" THEN PRINT
"WRONG !!!":GOTO 20
PRINT
As well as testing to see if two strings are the same,
you can use the (greater than' (» and (less than'
( <) tests to compare strings.
10 IF "B" > "A" THEN PRINT "OK"
This works because the letters are stored as
numbers. The computer is in fact comparing the
ASCII codes of the letters in the strings. This is
very useful because it allows strings to be sorted
into alphabetical order, as we will show later in
this chapter.
STRING MANIPULATION
Atari BASIC differs from most other dialects of
BASIC in the way in which strings are handled.
Characters can be copied from strings, and can be
inserted into strings to replace some of the
characters already there. To illustrate the various
commands we will use a string A$ which contains
the first 10 letters of the alphabet. The string is
defined by:
Position
1
2 3
4 5
6
7
8 9 10
Character A
B
CDEFGH I
J
The string A$
DIM A$(30)

Atari XL Specifications

General

Release Year	1983
CPU	MOS Technology 6502C
Graphics	ANTIC, GTIA
Sound	POKEY (4 channels)
Storage	Cassette tape
Ports	Cartridge
Operating System	Atari BASIC
CPU Speed	1.79 MHz
RAM	64 KB