Atari 800 XL ROSE User manual

SERVICE MANUAL
FOR THE
ATARI 800XL 'COMPUTER

SERVICE MANUAL
FOR THE
ATARI 800XL COMPUTER
Electronic Dimsnsions Post Office Box 1846 San Luis Obispo California 93406 USA

All of the information contained In this manual is believed to bo accurate and reliable. However,
no responsibility shall be assumed for any consequences arising out of the use of this material.
Atari and 800XL are registered trademarks of Atari, Inc.
Reproduction of this manual in any form is prohibited.
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TABLE Q£_ CONTENTS
SECTION 1- THEORY OF OPERATION
User Interface
Mechanical Theory
Electrical Theory
6502C CPU Microprocessor
Alphanumeric Television InterfaceController (ANTIC)
Graphic Television Interface Adaptor (GTIA)
POT KEYboard Integrated Circuit (POKEY)
Peripheral Interface Adapter (PIA)
Memory (ROMs and DRAMs)
Memory Management Unity (MMU)
Operating System ROM
RF Modulator
Monitor Output
Power Supply
System Interface
Serial Input/Output (SIO) Interface
Controller Jade Interfaces
Parallel Bus Interface (PBI
)
Cartridge Interface
Keyboard Interface
SECTION 2-SELF TESTING
Overview
Equipment Needed
Self Test Features
Description of Self Tests
Memory Test
Audio Yisual Test
Keyboard Test
All Tests
SECTION 1-DISASSEMBLY/ASSEMBLY
SECTION 4-TROUBLESHOOTING
AGuide to Aid in the Rapid Diagnosis of Problems
SECTION 5- SCHEMATIC AND PARTS LIST
Parts List
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A

SECTION I
THEORY OF OPERATION
The Atari 800XLWIs an enhanced version of the existing ATARI Computer Systems. It can be
used with any of the existing Atari peripheral devices used with the
400’V600XL"V800,M/120QXLMComputers.
The printed circuit board contains 64K of RAM ,an operating systems that contains ore 16K X8
ROM and an on-board Atari BASIC programming language I.C. The console contains the keyboard
and four function keys (including aHELP key), plus aRESET key, adetachable (RF) TV interface
cable, connector Jack for daisy-chaining peripherals and connecting hand controllers, asingle
cartridge slot, ore status LED (POWER), a5 pin DIN Monitor Jack, and aparallel bus interface
USER INTERFACE
The Atari 800XL is ageneral purpose microcomputer that uses a6502C microprocessor. The
800XL console is the central processing unit for its respective system.
The right side panel contains the controller jacks that accept the Atari X-Y joysticks and paddle
controllers.
The rear panel contains the serial input/output (SIO) jack, the parallel bus interface, theRF
jack, the monitor jack, the channel 2-3 switch, the power in jack, and the power switch
(On/Off).
The console has a3/4 stroke, 56 key, alphanumeric keyboard, that includes special characters
and controls, space bar, four function keys, HELP key, and power indicator. The function and
HELP keys are discussed below.
FUNCTION KEYS
HELP -Returns to main self-test menu from individual test and for future software
development for user “help" functions. If you are familiar with I200XL operation, this kev
do&noi function the same.
OPTION -Allows the player to choose variations of aprogram. If the OPTION Key is not
depressed and held at the time the computer is turned ON, the built-in BASIC is automatically
enabled. If the OPTION key is depressed and held at the same time the computer is turned ON, the
on board BASIC is disabled and, when there is no cartridge or diskette in the system,’ the
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Self-Test menu appears.
RESET -Interrupts aid restarts the operating system (OS) or cartridge. When pressed while
the computer is ON, this key enables the BASIC.
SELECT -Selects different program or game variations.
START -Starts the gone or program.
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To Cartridge To Joysticks, Paddles, Etc.
System Block Diagram
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MECHANICAL THFORV
The 800XL computer console contains asingle motherboard which houses all the chips of the
system and provides connectors for interfacing external modules to the console. It includes the
CPU,RAM ,OS and BASIC ROM's. The motherboard uses acommon address bus, data bus aid clock
lines. The sixteen-line address bus allows the microprocessor to directly address 64K memory
locations. The eight- line data bus provides the communication and data path between the
functional modules. The power is provided by an external power supply and routed throughout
the console
The keyboard is the user interface with the computer.
The keyboard connects to the PC Board by a24-connector ribbon cable.
All peripherals connect to the 800XL either through the SIO connector or the PBI. Power enters
through the 7-Pin DIN connector on the rear panel. Power On/Off is controlled by the ON/OFF
switch on the rear panel. RF to the TV switchbox arrives from an RCA phonoconnector and RF
cable. Composite Video composite luminance, and audio signals to the monitor arrive from a5
pin DIN monitor jack on the reer panel.
ELECTRICAL THFORV
DIGITAL HARDWARE
The digital hardware consists of:
*The 6502C CPU microprocessor
*The Alphanumeric Television Interface Controller (ANTIC)
*The Graphics Television Interface Adaptor (GTIA)
*The POT KEYboard Intecrated Circuit (POKEY)
*The Peripheral Interface Adaptor (PIA)
*The Memory (Operating System ROM ,64K RAM ,Atari BASIC ROM ,Rev. B)
*Miscellaneous Logic
Memory Management Unit (MMU)
Delay Line
*Parallel Bus Interface (PBI
)
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6.502C CPU Microprocessor
The 6502C CPU microprocessor contains register flags, interconnections, arithmetic logic,
control logic, and all recognized operation codes. The characteristics of the microprocessor
include:
*Byte-oriented structure
*Decimal and binary arithmetic modes
*Integral clock circuit
*Seven addressing modes
*Single +5 volt DC power requirement
*Stack pointer
*Two interrupt levels
*151 opcodes
*64K address range
*True Indexing
Ground VSS
Ready Input RDY
Phase 1Clock FPH1
Interrupt Request IRQ
NC
Non Maskable Input NMI
+5V Power NC
VCC
Address Bus AO
Address Bus A1
Address Bus A2
Address Bus A3
Address Bus A4
Address Bus A5
Address Bus A6
Address Bus A7
Address Bus A8
Address Bus A9
Address Bus A10
Address Bus All
V/
1•40
239
338
437
536
635
734
833
932
10 31
11 30
12 29
13 28
14 27
15 26
16 25
17 24
18 23
19 22
20 21
kti> Reset
FPH2 Phase 2Clock
SO Set Overflow
FPHO Phase 0Clock (in)
R/¥ Read/Write
MT HALT Input
NC
DO Data Bus
D1 Data Bus
D2 Data Bus
D3 Data Bus
D4 Data Bus
D5 Data Bus
D6 Data Bus
D7 Data Bus
A15 Address Bus
A14 Address Bus
A13 Address Bus
A12 Address Bus
VSS Ground
6502C (Modified)
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