Atari 400 Field Service Manual

Testing
With And
Without The
SALT II
Cartridge
All
tests
are reviewed
in this
section.
Procedures
for the
use of the
tests
are
detailed
in Section
5,
*00 Diagnostic
Flowchart,
and Section
7,
800
Diagnostic
Flowchart.
OVERVIEW
OF TESTS
A variety
of test
routines
assist
you
in
identifying
probable
sources
of
problems
within
the
computer
console.
Power-Up
Test
This
test
prepares
the Console
for the remainder
of the tests.
Should
the
Console
fail
this
test,
no other test
results
can be
considered valid.
•
Format:
Connect
the power
adaptor
to the
Computer
and the
Computer
to
the television
set. Make
sure there
is
not a
cartridge
in the
console
—turn
the
POWER
switch ON.
The
words ATARI
COMPUTER
-
MEMO PAD
should
appear
on the
screen
in the
upper left
corner.
Keyboard
Test
This
tesx
verifies
that
all keys
of the
keyboard
are
properly
functioning.
This
test
-Iso
verifies
that
the POKEY
chip's
keyboard
functions
are
operating
properly.
If
one
key
faUs,
then
the
problem
is Ukely
the
keyboard.
If
more
than
one key
fails,
you
must
perform
further
tests.
(These
tests
are
discussed
later in
this
section.)
•
Format:
Depress
each key
of the
keyboard.
As
you press
each key,
watch
the
screen
to verify
if the
computer
is
echoing
the key.
Be
certain
to use
the
CTRL
key
with
other
keys.
This
checks
special
graphics
functions
not
tested
elsewhere
(See
Figure 3-1).
RAM
and
ROM
Test
This
test
verifies
that
the
CPU,
RAM,
and ROM
chips
are ail properly
functioning.
•
Format:
Due
to the
possible
complexity
of this
test,
it has
been
broken
into
four
subsections.
I.
Turn
the
POWER
off,
insert
the SALT II
cartridge
(for
the
800, use
the
left
cartridge
slot),
and turn
the POWER
on. The SALT
Header
should
appear
on the
television
screen
(See Figure 3-2).
This
verifies
that
the
CPU,
Operating
System
(OS) ROMS,
and the
lower RAM
are
functioning.
ATARI
Home
Computer
3-2

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)