Atari 400 User Manual

Atari BASIC Reference Guide 159
EXAMPLE
POKE 83,20
The previous example consists of a statement that changes the
right margin of the screen to column 20 . The value of the right
margin is stored in memory location 83.
POP
The POP statement causes a program to ignore the GOSUB or
ON / GOSUB statement that was executed last.
CONFIGURA
liON
POP
In
effect, a GOSUB or ON / GOSUB statement is converted to a
GOTO or ON / GOTO statement when POP is executed. The
program "forgets" that it is in a subroutine . As a result, when a
POP statement is executed, the next RETURN statement
branches
the program control to the line after the GOSUB
statement befor e the previous GOSUB statement. In other
words, the program "fo rgets" where the subroutine was called
from , so it returns to a previous GOSUB statement.
A
POP statement is used, in general, to exit a subroutine .
10 X = 5
20 Y = 10
EXAMPLE
30 GOSUB 100
40 END
100 PRINT X
110 IF X>O THEN POP : GOTO 130
120 RETURN
130 PRINT Y
140 END
RUN
5
10

Atari 400 Specifications

General

Manufacturer	Atari
Model	400
Type	Home Computer
Release Year	1979
CPU	MOS Technology 6502
CPU Speed	1.79 MHz
ROM	10 KB
Operating System	Atari OS
Keyboard	Membrane keyboard
RAM	8 KB (expandable to 48 KB)
Graphics	ANTIC and GTIA chips
Sound	4 channels
Display	RF output for connection to TV
Storage	Optional cassette tape drive or floppy disk drive
Ports	Cartridge
Display Resolution	320x192 (16 colors)