Atari 800 User Manual

72 User's Handbook to the Atari 400/ 800 Comp uters
ON, GOSUB Statement
The ON , GOSUB statement is very similar in na tur e to the ON ,
GOTO statement. The following statement is an example of an
ON , GOSUB statement.
100 ON X GOSUB 1000 , 2000, 3000
If the va lue of X is 1, the subro utin e at line 1000 is executed. If X is
2, the s ubr o utin e at lin e 2000 is executed. I f X is 3, the subro utin e
at
line 3000 is executed . If X eva lu ates to 0 or to a number greater
than
3, the statement imm ediately following the ON, GOSUB
statement will be executed.
If ON , GOSUB causes a branch to a s ubr o utin e, program co ntrol
will rev ert to the line imm ediately following the ON, GOSUB
statement, once the subrout ine h as been exec ut ed.
Break Key and CONT
Generally, Atari BASIC programs can be stopped by pressing the
Break key. When the Break key is used to stop program
execution, a m essage similar to the following will be displayed.
STOPPED AT LINE XXX
In actual practice, the XXX will be replaced by th e line numb er
where program execution stopped.
Once program execution has been stopped by pressing the
Break key,
the comp ut er w ill return to the immediate mode. If
you wish program execution to resume, enter the CO NT
command at the keyboard. Program contro l will resume with the
lin e following the one wh ere the program break occurred.
System Reset Key
Program exec uti on can al so be stopped at any time by pressing
the System Reset key. H owever , System Reset functions
som ewhat differently than Break.

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