Atari 800 Field Service Manual

The Printed
Circuit Boards (PCBs)
piug into
sockets
on the motherboard,
using a
common Address Bus, Data Bus
and clock
lines. The various
power
requirements
are
routed
from the power
supply through
the motherboard
to all printed
circuit boards.
The keyboard
connects directly
to the motherboard
through
a
ribbon
connector.
The
sixteen-Une
Address Bus allows
the microprocessor
to directly
address 64K of memory.
The
eight-line
Data Bus provides
the communication
and data
path between the
functional
modules.
Figures 1-8
thru
1-17
at the end of this
section provide
function block
diagrams of
PCBs
in the *00/800
systems.
Motherboard
The motherboard
ties all components
of the
computer
system together. It
also
performs
a variety
of logic
functions. All PCBs
and
connector
cables plug
into the
motherboard
and allow
communication
between the
functional
blocks of the
'^OO and
SOO
Computer
Consoles.
The
motherboard
also performs
the following:
•
Generates
a 3.58 MHz
master
clock for the
Central
Processing Unit's
PCB.
•
Generates
the Power-ON
RESET
for the
Central Processing
Unit PCB
and
the peripherals.
•
Provides
the driving
circuitry for
the Key-Press
signal
from the
Central
Processing
Unit
PCB
to the
Console speaker.
•
Converts
signals
from
the various hand
controllers
into
recognizable
data
for the
microprocessor.
•
Buffers
and drives
the data
lines between
the
Central
Processing
Unit PCB,
the RAM
PCBs,
and the
remainder
of
the system.
•
Does
the first
memory
map
decoding
of the
possible 64K
address
locations
into 8K
blocks
for the microprocessor.
•
Generates
control
signals
for the
peripheral devices.
•
Receives
video
data
from the
Central Processing
Unit PCB,
converts
it
into
a composite
video
and routes it
to the power
supply PCB.
•
Combines
the
sound
from
the Computer
system
and the
audio track
of
prerecorded
cassettes.
•
Develops
the
sound
subcarrier
for the
television
audio
as part of the
composite
video.
ATARI
Home
Computers
1-^

Atari 800 Specifications

General

Processor	MOS Technology 6502
Processor Speed	1.79 MHz
ROM	10 KB
Graphics	ANTIC and GTIA chips
Release Year	1979
Display Resolution	up to 320 x 192
Colors	128 colors
Sound	4 channels
Storage	Cartridge, cassette, floppy disk
Ports	Cartridge, serial, monitor
Operating System	Atari OS