Atari 400 Field Service Manual

Gray
Bar Test
This
test
verifies
that the
CTIA (GTIA)
is generating
the three LUM
iines.
By
pressing the
command letter G and then
RETURN,
this test
activates.
Figure
3-6
iiiustrates the screen
display of
the Gray Bar
Test. The
screen
is divided
into eight equal sized horizontal
bars.
The
bar at the top
of the screen should be black
and subsequent
bars
should
progress to white
at
bar
eight.
The
bars should
lighten in
even shades. The
screen should be
steady and unchanging. These lines
may have minor
glitches
at their edges. A
thin white line should always
appear just over
the top
(black) bar.
No color should
appear anywhere on the
screen.
The
areas
above
the top
(black)
bar and below the
bottom (white) bar
are of no importance
to this test. This
test should
be left on for
at least 60
seconds to ensure that
there is no "flashing" of
color or
shifting of the
gray bars.
Figure 3-6.
Gray Bar Test Screen
ATARI
Home
Computer
3-8

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)