Atari 520STE Quick start guide

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Atari STe 520/1040
Computer Field Service Manual
Part Number: C302481–001 Rev A
August 1991

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TABLE OF CONTENTS
SECTION ONE: INTRODUCTION ...................................................................................1
1.0 Overview ..........................................................................................................1
1.1 Main Components ............................................................................................1
1.2 Case Design ....................................................................................................1
1.3 Power Supply ...................................................................................................3
1.4 Negative Supplies ............................................................................................3
SECTION TWO. THEORY OF OPERATION .................................................................. 4
2.0 Overview ..........................................................................................................4
2.1 Main System .................................................................................................... 4
2.2 Audio/Video Subsystem ...................................................................................4
2.3 InputlOutput Subsystems .................................................................................5
2.4 Microprocessing Unit ........................................................................................5
2.5 GSTMCU ..........................................................................................................5
2.6 Main Memory ................................................................................................... 6
2.7 Direct Memory Access .....................................................................................7
2.8 Multi–Function Peripheral Control ....................................................................7
2.9 Audio/Viideo Subsystem ..................................................................................8
2.10 Digitized Sound ................................................................................................10
2.11 Genlock and the STE .......................................................................................10
2.12 Input/Output Subsystems .................................................................................11
2.13 System Startup ................................................................................................ 21
2.14 System Errors .................................................................................................. 22
SECTION THREE: TESTING .......................................................................................... 24
3.1 Overview ..........................................................................................................24
3.2 Test Configuration ............................................................................................25
3.3 Troubleshooting a Dead Unit ........................................................................... 25
3.4 Diagnostic Cartridge ....................................................................................... 26
3.5 Power Up Sequence ....................................................................................... 26
3.6 Test Menu ....................................................................................................... 28
3.7 RAM Test ........................................................................................................ 28
3.8 ROM Test ........................................................................................................ 29
3.9 Color Test ........................................................................................................ 29
3.10 Keyboard Test ................................................................................................. 30
3.11 MIDI Tests ........................................................................................................31
3.12 RS232 Tests .................................................................................................... 31
3.13 Audio Test ........................................................................................................32
3.14 Timing Tests .................................................................................................... 33
3.15 DMA Tests ....................................................................................................... 34
3.16 FIoppy Disk Tests ............................................................................................ 34
3.17 Printer and Joystick Port Tests ........................................................................ 36
3.18 Monochrome Monitor .......................................................................................37
3.19 Hard Disk WriteIRead ...................................................................................... 37
3.20 Graphics Chip BLiT ..........................................................................................38
3.21 Error Codes (quick Reference)......................................................................... 38
SECTION FOUR: DISASSEMBLY/ASSEMBLY …………………………………………… 43
4.1 STE Disassembly .............................................................................................43
4.2 STE Reassembly ............................................................................................. 44

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SECTION FIVE: SYMPTOM CHECKLIST ………………………………………………….. 45
5.1 Display Problems .............................................................................................45
5.2 Disk Drive Problems .........................................................................................45
5.3 Keyboard Problems ..........................................................................................46
5.4 MIDI Problems ................................................................................................. 46
5.5 RS232 Problems ..............................................................................................46
5.6 Printer Port Problems .......................................................................................46
5.7 Hard Disk Port Problems ..................................................................................46
5.8 DMA Sound ......................................................................................................46
SECTION SIX: DIAGNOSTIC FLOWCHARTS ………………………………………….…..47
6.1 Replacement Procedures .................................................................................47
6.2 Handling of Integrated Circuits .........................................................................47
SECTION SEVEN: PARTS LIST ..................................................................................... 52
SECTION EIGHT: GLOSSARY ....................................................................................... 56
SECTION NINE: SCHEMATICS AND SILKSCREENS ...................................................58

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Reproduction of all or any portions of this manual is not allowed without the specific
written consent of Atari Corporation.
Every effort has been made to ensure the accuracy of the product documentation in
this manual. However, because Atari Corporation is constantly improving and
updating its computer hardware and software, it is unable to guarantee the accuracy
of printed material after the date of publication and disclaims liability for changes,
errors. or omissions.
These documents are for repair service information only. Part numbers are for
reference only. Only parts on current dealer parts lists are available. No license is
given for any use by the possession of these documents and may not be reproduced
in any form without the written approval of Atari Corporation.
Atari, the Atari logo, STE, TOS, BLiTTER , SM124, SC1224, SF314, SF354,
PCF554, SLM804, CDAR504, Atari BASIC, and Atari SFP–004 are trademarks or
registered trademarks of Atari Corporation. Centronics is a registered trademark of
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Microsoft Corporation. Epson is a registered trademark of Seiko–Epson Corporation.
VT and DEC are registered trademarks of Digital Equipment Corporation.
Copyright © 1991, Atari Corporation
Sunnyvale, CA 94089–1302
All rights reserved.

1
SECTION ONE: INTRODUCTION
1.0 OVERVIEW
The 520STE and 1040STE are designed as integrated units with keyboard,
processor, memory, and I/O control in one package. The 520STE has 520 kbytes
(524.280 bytes ) of RAM, and the 1040STE has 1040 kbytes (1,048,568 bytes) of
RAM. The 1040STE and 520STE both have a built–in 1 megabyte floppy disk drive
(unformatted). Both the 520STE and 1040STE come with a modulator for TV output.
The 520STE and 1040STE both have the power supply integrated into the case.
1.1 MAIN COMPONENTS
•524K RAM (1048K for the 1040STE)
•Main Board with modulator (except French Peritel)
•Keyboard Assembly
•RF Shield (upper and lower) and Power Supply
•Plastic Case (upper and lower)
•Mouse
•Power Supply
•Disk Drive
1.2 CASE DESIGN
The 520STE and the 1040STE are nearly identical. The upper case has openings for
the keyboard and a lens for both the power indicator LED (front left corner) and the
Disk Drive Activity LED (mid right side). (see Fig. 1–1)
Figure 1–1: 520STE Upper Case

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Figure 1–2. 1040STE Upper Case
The left side panels of both machines have slots for the expansion cartridge, two
MIDI ports and two game controllers.
Figure 1–3. STE Left Side Panel
The right side panel has a slot for the floppy disk drive.
Figure 1–4. STE Right Side Panel
The STE back panel contains (left to right) the modem (RS232) connector, printer
connector, hard disk/DMA connector, external floppy disk connector, television
output, monitor connector, power switch, stereo output (right and left), AC power
input, and reset button. (see Fig. 1–5)

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Figure 1–5. STE Back Panel
1.3 POWER SUPPLY
The 520STE and 1040STE have an integral switching power supply providing +5V
and +12V. There is a 2A fuse. Voltage should be adjusted to 5.1V. The power supply
has overcurrent protection; if the fuse is blown, a catastrophic failure is likely, such
as shorted primary
Power Supply Rating
Current out: 3A at 5V, 0.9A at +12V
Max. power in: 33.5W
Typical (in system) Demand.
Typical current: 1.75A at 5V, 86 mA at + 12V
Max. current: 2.2A at +5V, 90 mA at +12 (during disk access)
1.4 NEGATIVE SUPPLIES
The STE motherboard contains two small switching voltage regulators (the TL497 or
equivalent) that are used to provide additional voltages.
0204 is used to generate the positive and negative voltages for the RS232C line
drivers. These voltages are normally ±12 VDC.
U205 is used to generate a –5 VDC supply for the audio subsection. This output is
heavily filtered to reduce the switching noise that might otherwise appear in the
audio output.

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SECTION TWO: THEORY OF OPERATION
2.0 OVERVIEW
The 520STE and 1040STE share a common architecture, using the same LSI chip
set. The most significant difference is the addition (to the 1040STE) of one bank of
512K of RAM, for a total of 1024K (1,048,568 bytes). Except for the additional RAM,
the differences between the 520STE and 1040STE are transparent to software. The
hardware can be considered as consisting of a main system (central processing unit
and support chips) and several Input/Output subsystems.
2.1 MAIN SYSTEM
•MC68000 running at 8 MHz
•256 kbyte ROM
•512/1024 kbyte RAM
•Direct Memory Access Support
•System Timing and Bus Control
•Interrupt Control
2.2 AUDIO/VIDEO SUBSYSTEM
The STE has bit–mapped video display, normally using 32,000 bytes of RAM,
relocatable anywhere in memory. There are three display modes available:
RGB, with the ability to be GenLocked:
1. 320 x 200 pixel, 16 color palette from 4096 selections
2. 640 x 200 pixel, 4 color palette from 4096 selections
Monochrome:
3. 640 x 400 pixel, monochrome monitor interface
2.2.1 Audio Output
The STE has a programmable sound chip and 8–bit stereo DMA at 4 playback
frequencies.
2.2.2 Television Interface
NTSC, PAL I and PAL B.

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2.3 INPUT/OUTPUT SUBSYSTEMS
•Intelligent keyboard with 2 button mouse/joystick interface
•Parallel printer interface
•RS232C serial interface
•Floppy disk drive and connector for external drive
•Game controller ports
•Hard disk drive interface (ACSI)
•Musical instrument network communication: Musical Instrument Digital
Interface (MIDI)
2.4 MICROPROCESSING UNIT
The STE uses the Motorola MC68000 16–bit external/32–bit internal data bus. 24–bit
address bus microprocessor, running at 8 MHz.
2.5 GSTMCU
GSTMCU is such an important component that it is involved in nearly every operation in the
computer. The functions may be summarized as follows:
CLOCK DIVIDERS takes the 16 MHz clock and outputs 8 MHz, 4 MHz, and
500 kHz clocks.
VIDEO TIMING Blank, DE (Display Enable), Vsync and Hsync are used to generate
signals for the video display. There is a Read/Write register in GSTMCU which may
be written to configure for 50 or 60 Hz operation or 71 Hz monochrome operation
(done by the Operating System).
INTERRUPT PRIORITY interrupts from the MFP and video timing are coded into
four levels of priority on outputs IPLO and IPL1 to the 68000. These levels corres-
pond to no interrupts, MFP interrupts, VSYNC interrupt, HSYNC interrupt.
level 7 reserved
level 6 MFP
level 5 unused
level 4 VSYNC
level 3 unused
level 2 HSYNC
level 1 unused
SIGNAL AND BUS ARBITRATION GSTMCU decodes addresses to generate chip
selects to the 6850s, MFP, DMA Controller. Programmable Sound Generator,
Memory Controller, and ROMS. It receives signals from the MFP, DMA, Memory