Atari 400 Field Service Manual

Figure
8-1.
Joystick (X-Y
ControUer)
If
the
stick is pushed
forward
and
to the right
at the same time
(that is, in
a northeast
direction),
both
the forward
and
right keypad
ck)se simultaneously,
which
causes the
POKEY
to
see two switch
closures
happening
at once (See
Figure S-2). The
result is
that
the
object being
controlled
on the screen moves
diagonally. With
the four
keypads,
8
different
directions
can be
attained. The
pushbutton
determines whether
the keypad
beneath
it
is either
open
or closed. (Earlier models
were
spring loaded.)
ATARI
Home
Computer
8-2

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)