Atari 400 User Manual

244 User's Handbook to the Atari 400/ 800 Computers
For example, when the following program is executed, line 500
will cause a second program (PROGB.BAS) to be exec ut ed.
100 REM PROGA.BAS
200 A = 9: B = 10
300 C = A * B
400 PRINT C
500 RUN "0: PROGB.BAS"
When the new program is load ed in line 500, all variable values
will be cleared before PROGB.BAS is l oaded. This is due to the
fact that the RUN statement as used in line 500 exec ut es a LOAD
statement. The LOAD statement in turn executes a NEW
statement which erases any exi st ing programs in memory and
clears
all variables.
USING DATA FILES ON DISKETTE
The BASIC statements PRINT# and PUT are used to store data on
a diskette. INPUT# and GET are used to read data int o RAM from
a diskette.
Opening a Disk File
Before a disk file can be used, it must first be opened with the
OPEN statement. The OPEN statement will open an
input / o utput channel to the file specified as its parameter. Th e
OPEN statement uses the following configurat ion :
OPEN #channe/, task , va lu e, D#:filename
The first parameter in the OPEN statement indi cates the channe l.
Before an external device can be accessed either for input or
output, a channel to the device must have been opened .
The
OPEN statement ass igns a channe l to an externa l device.
Once a c hann el is assigned, the device can subsequent ly be
accessed via its channel number. If an OPEN statement attempts
to open a channe l which is already open, an error will occur.

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)