Atari 800 User Manual

Advanced Atari BASIC 77
the following program , a substring is used to change X$ from
"JOHN JOH NSON" to "JOHN J ACKSON".
100 DIM X$(15)
200 X$ = "JOHN JOHNSON"
300 X$(6,1 2) = "JACKSON"
400 PRINT X$
500 END
RUN
JOHN JACK SO N
If an e rror occurs with a s ub st ring specificat ion , error number 5
will be di sp layed.
String Concatenation
The process of joinin g together one or more strings is known as
co ncate nation . Th e LEN function is used in co njun ct ion with
substrings in concatenation. Th e LEN function is us ed to return
the l engt h of its string arg um en t. L EN u ses the following
config ur ation.
LE N (string)
The following program illu strates st ring con ca tenation in Atari
BASIC.
100
DIM X$(15), Y$ (15)
150 X$ = '''':Y$ = ""
200 X$ = "J OHN"
300 Y$ = "JOHNSON"
400 X$( LEN (X$) + 1) = Y$
500 PRINT X$
600 END
RUN
JOHNJOHN SON
The actual concatenati on takes place in lin e 400. Here, Y$ is
added
onto the end of X$ to form a new X$. Notice that 1 was
added to the result of LEN(X$) . This ca u ses Y$ to be added
beginning at the first blank space following the end of the
original X$.

Atari 800 Specifications

General

Processor	MOS Technology 6502
Processor Speed	1.79 MHz
ROM	10 KB
Graphics	ANTIC and GTIA chips
Release Year	1979
Display Resolution	up to 320 x 192
Colors	128 colors
Sound	4 channels
Storage	Cartridge, cassette, floppy disk
Ports	Cartridge, serial, monitor
Operating System	Atari OS