Atari 400 Instruction Manual

USER'S HANDBOOK
TO THE
ATARI 400/800® COMPUTERS
by:
Jeffrey
R. Weber
Stephen J. Szczecinski
Weber Systems, Inc.
Cleveland, Ohio

Published by :
Weber Systems, Inc.
8437 Mayfield Road
Cleveland, Ohio 44026
For
information on translations and book distributors outside of
the United States, please contact WSI at the above address.
User's Handbook To The Atari 400j800® Computers
First Edition
Copyright© 1983 by Weber Systems, Inc.. All rights reserved.
Printed in the United States of America. No part of this
publication may be reproduced , stored in a retrieval system, or
transmitted in any form or by any means, electronic, mechanical,
photocopy , recording , or otherwise without the prior written
permission of the publisher.
Library of Congr e ss Ca talog Card Number 82-051088
ISBN 0-938862-15-4
Typesetting: Chell ey Hoffm an
Production & Design: Beth Cammarn

CONTENTS
1. INTRODUCTION TO THE ATARI COMPUTERS
AND PERIPHERALS
Atari 400 and 800 7. Atari 800 Specifications 9.
Atari 400 Specifications 10. Atari Keyboard 11.
Atari Video Display 11. Plug-In Cartridge
Hatches 13. Computer Memory 13. Atari 410
Program Recorder 14. Atari 810 Disk Drive 15 .
Atari Printers
16. Atari 850 Interface Module 16.
Game Controls 17. Software 17. Operating
Systems 17. Languages 18. Applications
Programs 18.
2. INSTALLATION AND OPERATION OF ATARI
COMPUTERS
Introduction 19. Installing the Atari 400 21.
Installing the Atari 410 Recorder 21 . Installing
the Atari 810 Disk Drive 21 . Installing the Atari
820 Printer 23 . Installing the Atari 822 Printer 24.
Installing the Atari 825 Printer 24 . Installing a
ROM Cartridge 25 . Power On 26. Keyboard 30.
System Reset Key 31 . Select Key 31 . Option Key
31. Start Key 31. Return Key 32. Break Key 32 .
Shift Key
32. Ctr! Key 33. Caps/Lowr Key 33 . .II\..
Key 34 . Arrow Keys 34. Back S Key 35. Clear
Key 35. Insert & Delete Keys 35 . Tab Key 35. ESC
Key 36 . Auto Repeat 36. Display Line Length 36.
7.
19.

3. INTRODUCTION TO AT ARI BASIC
Immediate & Program Modes 37. Line Numbers
38. NEW 40. END 40. Program Execution 40.
Program Lines & Display Lines 41. Multiple
Statement Program Lines 41. Abbreviating
Keywords 42. Listing a Program 42. Error
Messages 43 . BASIC Data Types 44 . Floating
Point Numbers 44 . Scientific Notation 45 .Tables
& Arrays 49. Expressions & Operators 51 .
Compound Expressions & Order of Evaluation
52.
Arithmetic Operations 53. Relational
Operators 55. Logical Operators 56. Atari
BASIC Statements 59 . Remark Statements 59 .
Assignment Statements 60 . DATA , READ 60 .
Outputting DATA 62. INPUT Statements
64. Loops 66. Nested Loops 67 . Conditional
Statements 68. Branching Statements 68. ON,
GOTO 70. Subroutines & GOSUB Statements
70. ON, GOSUB 72. Break Key & CONT 72 .
System Reset Key
72 . STOP 73. END 73 . Atari
BASIC Functions 74 .
4. ADVANCED AT ARI BASIC
Atari ASCII 75 . String Handling 76. Substrings
76. String Concatenation 77 . CHR$ & ASC
Functions 78. Escape Sequences in Strings
79. Graphics Characters in Strings 80. Variable
Storage 82. PEEK & POKE 83. Screen Output
Programming 84. Using the Carriage Return in
Cursor Positioning 84. TAB 85 . Moving the
Cursor With Escape Sequenc es 86. Home
Cursor 87. POSITION 87. Changing the Display
Screen Margins 88. Screen Input Programming
88. Prompt Messages 88. Input Response
Checks 89.
5. ATARI BASIC REFERENCE GUIDE
ABS 92. ADR 92. AN D 92. ASC 94. A TN
94. BYE 95. CLOAD 95. CHR$ 96. CLOG 96 .
CLOSE 97. CLR 97. COLOR 98 . COM 102.
37.
75.
91.

CO NT 103. COS 104 . CSAVE 104 . DATA 105 .
DEG 106 . DIM 107 . DOS 110 . DRAWTO 112.
END 114. ENTER 114. EXP 115. FOR 116. FRE
118 . GET 119 . GOSUB 123. GOTO 125.
GRAPHICS 126 . IF 126. INPUT 129. INT 132.
LEN 133 . LET 133 . LIST 134 . LOAD 136 . LOCATE
137 . LOG 139. LPRINT 139 . NEW 140. NEXT
141 . NOT 142. NOTE 143 . ON 144. OPEN 145.
OR 153. PADDLE 154. PEEK 155 . PLOT 156.
POINT 157. POKE 158. POP 159 . POSITION
160. PRINT 161 . PTRIG 166 . PUT 166. RAD 169.
READ 170. REM 171 . RESTORE 171 . RETURN
172. RND
172. RUN 173. SAVE 174 . SETCOLOR
175 . SGN 175. SIN 175 . SOUND 176 . SQR 177.
STATUS 177. STICK 178. STRIG 179. STOP 180.
STR$ 181 . TRAP 181 . USR 182 . VAL 183 . XIO
184.
6. ATARI 410 PROGRAM RECORDER
Introduction 189. Data Files 189. Program Files
190 . Saving Programs 190. Program Recording
Formats 191. Loading a Program 192. RUN C:
195. Reading and Writing Data 197 . Opening
Data Files198. Closing Data Files200. Writing to
a Data File 200. Reading From Data Files 202.
7. AT ARI 810 DISK DRIVE
Types of Disks 205. Hard Disks 205 . Winchester
Disk Drives 206. Floppy Diskettes 207. Tracks &
Sectors 208 . Hard & Soft Sectors 209 . Single &
Doubl e Sided Diskettes 211. Diskette Density
211 .
Write Prot e ction 212 . Disk Files
213. Filename Match Characters 213. Atari DOS
215. Disk Buffer 21 7. Booting DOS 217. DOS
Menu 218. Disk Directory 220 . Run Cartridge
222 . Copy File 223. Delete File 227. Rename
File 228. Lock File 230 . Unlock File 231. Write
DOS File 231 . Format Diskette 232 . Duplicate
Disk 233 . Binary Save 234. Binary Load 236 . Run
At Address 237. Create MEM.SAV 238.
Duplicate File 239 . Saving BASIC Programs 240.
189.
205.

Loading a Program 242. Chaining Pr og rams
243. Op e nin g a DiskFil e 244 . Clos in g a Data File
246. Writing to a Data File 2 47 . R ea ding Fr om a
Data File 248. NOTE
and POINT 250.
8. Al ARI PRINTERS
LIST P: 253. LPRINT 25 4. PRINT# & PUT 2 55.
Print er Buff er 255. Print er C haracter Sets
255.
Atari 825 Contro l Characters 256. Line Feed
258.
Rever se Line F eed 258 . Ha ld-Line F eed &
R
eve rs e Half-Lin e F eed 259. Car riage Re turn
259. Und e rlinin g 259. Standard, Con densed, &
Proportionall y Spa ce d Charact er Sets 260.
Backspace & 1-6 D
ot Spaces 26 0.
9. AlARI GRAPHICS & SOUND
GRAPHICS 263. GRAPHICS 0 263. Color
R eg iste rs & SETCOLOR 265 . GRAPHICS 1 & 2
267.
COLOR 272 . PLOT 277. ORA WTO 278.
GRAPHICS 3 thru 8 278. POSITION 281.
LOCATE 282. PUT 283. XIO 283. Atari Sound
285.
APPENDIX A. Atari Error Messages
APPENDIX B. Atari BASIC Reserved Words
APPENDIX C. Atari ASCII Code Set
APPENDIX D. Atari 400/800 Memory Map
APPENDIX E. Atari PEEK & POKE Locations
Index
253.
263.
287.
294.
295.
301.
306.
315 .

CHAPTER 1.
INTRODUCATION TO THE ATARI
COMPUTER AND PERIPHERALS
Introduction
In this book, we will describe the Atari home computers as well
as the peripherals that can be attached to them such as disk
drives, cassette recorders, and printers.
In the first chapter of this book, we will discuss the features of the
Atari 400 and 800 computers , the 410 Program Recorder, the 810
disk drive , game controls , and the various Atari printers . In the
second chapter, we will discuss the installation and operation of
the Atari 400 or 800 and its various peripherals .
In the third and fourth chapters, we will discuss programming
the Atari in Atari's version of the BASIC programming language.
The
fifth chapter contains a reference guide to the various Atari
BASIC commands, statements, and functions.
In Chapters 6, 7, and 8, we will discuss the Atari Cassette
Recorder, Atari Disk Drive, and Atari printers in greater detail. In
Chapter 9, we will discuss the usage of graphics and sound on the
Atari 400 and 800 .
Atari 400 and 800
There are two Atari computer models; the Atari 400 and the Atari
800 (pictured in Illustration 1-1).
The Atari
400 and 800 are very similar. Both models function the
same and follow the same set of instructions. The difference
between the Atari 400 and 800 lies in the fact that the 800 has
features
that the 400 does not.
For instance,
the Atari 800 's memory can be expanded , while the

8 User's Handbook to the Atari 400/800 Computers
memory of the Atari 400 is more or less fixed. Also, with the Atari
800, a video monitor can be used for video output as well as a
regular television set. With the Atari 400, only aregular television
set can be used for video output. A video monitor offers a more
detailed picture than a regular television set. Also, the Atari 800
has a typewriter style keyboard while the Atari 400 has aflat panel
with the keys outlined on it. Finally, the Atari 800 allows two
accessory cartridges to be plugged in, while the Atari 400 allows
only one.
However, the Atari 400 does have one major advantage--it costs
less than the Atari 800.
From hereon, we will refer to both the Atari 400 and 800
collectively as the Atari, unless a distincion between the two is
necessary. Whenever we refer to one model, the reader can
assume that
the concept applies to the other model as well,
unless
we specify otherwise.
Illustration 1-1. Atari 800 Computer

Introduction to the Atari Computers and Periphe ral s 9
Atari 800 Specifications
The Atari 800 consists of a group of components which include
the following :
•
Computer Console
• TV Switch Box
• AC Power Adapter
• Atari 800 Op erator's Manual
• Atari BASIC Manual
• Atari BASIC Language
• Atari Educational System
The Atari
800 Console contains the central processing unit or
CPU, the operating system in ROM , 8K or 16K of RAM, and two
expansion slots for additional RAM. The Atari 800 console also
contains the keyboard, 2 cartridge slots, controller jacks, and a
serial I/ O port.
The TV switch box allows a regularTV set to be used as the Atari's
video display. The AC power adapter converts regular AC
current to a low voltage that can be used by your Atari. The AC
power adapter can be plugged into any normal household
outlet .
The Atari Educational System and Atari BASIC language are
contained in two cartridges. Operator's in structions are
includ ed with each of these.
The Atari
410 program recorder allows the use of programs
which have been stored on cassette tape. The Atari 410 also
allows the user to save his programs from RAM onto cassette
tape
for later use .
The Atari 800's software is
known as the operating system and is
contained on a 10K ROM cartridge. The operating system
controls the entire flow of information within the computer.
As shown in Illustration 1-2, the side panel of the Atari 800
contains several switches and jacks. The monitor jack can be
used
to connect a video display monitor or a video tape

10 User's Handbook to the Atari 400/800 Computers
Illustration 1-2. Atari 800 Side Panel
recorder to your Atari 800.
The Atari 410 Program Recorder, Atari 810 disk drive, and Atari
820 printer are all installed by plugging into the peripheral jack.
More than one device can be connected through the peripheral
jack via adaisy chain configuration, where all devices to be used
are
connected together. This is explained in more detail in
Chapter 2.
The 2-3 channel switch should be set to the same channel as the
television set being used for video output. Use channel 2 or 3,
whichever has the poorer reception.
The Atari 800 contains four controller jacks located in the front of
the console beneath the keyboard. These can be used for
connecting game controllers or a light pen.
Atari 400 Specifications
Your Atari 400 includes the Atari 400 console, as well as a TV
switch box , operator's manual, and an AC Power Adapter.

Introduction to the Atari Computers and Peripherals 11
The Atari 400 console contains the CPU, operating system in
ROM , 8K or 16K of RAM , one cartridge slot, controller jacks, and
one I/ O connector.
The TV switch box allows a regular TV set to be us ed for video
output for the Atari 400. The AC power adapter converts
household current to a low voltage that can be used by the Atari.
Atari Keyboard
The Atari
keyboard allows the user to interact with the
computer. The in st ructions entered at the key board are
transfered
to the computer. The keys on both the Atari 400 and
800 are arranged in the same order as on a regular typewriter.
However, the Atari keyboard contains several special keys not
found on a standard typewriter keyboard. These keys will be
discussed in Chapter 2.
As mentioned in the previous section, the Atari 800's keyboard
features a typewriter style keyboard with raised keys. The Atari
400 keys are identified on a flat panel on the front of the unit.
Atari Video Display
Generally , a home color television set is used as the video display
screen
for the Atari. A black and white television set can also be
used, in which case, the different colors will appear as various
shades
of gray.
The Atari
800 allows the use of a video monitor as well as a
television set
as its video display unit. A video monitor (either
color or black & white) tends to ca u se images to be displayed in
greater detail than a television set.
A television set
is connected to the Atari computer with aswitch
box that
is it se lf connected to the television's antenna terminal.
This is shown in Illustration 1-3. The switch box has two
positions. One position allows the set to be used with the Atari,
while the other allows the set to function as a televison.
If a video display monitor is being connected to the Atari 800, a

12 User's Handbook to the Atari 400/800 Computers
switch box is not necessary. This connection can be
accomplished by attaching the 5- pin plug into the socket on the
side of the Atari 800 . This is shown in Illustration 1-4.
Regardless
of whether a television set or a monitor is being
connected to the Atari, several different modes of display are
available.
One of these is the monochromatic text mode. This
mode is used to display one color plus white (ex. black and
white, blue and white, etc.). In the monochromatic text mode ,
the screen is divided into 24 lines of 40 characters each. Two
other modes are available for displaying text in up to four
different colors. Other modes are available for displaying
graphics. These
will be discussed in detail in Chapter 9.
Illustration 1-3. Atari/Television Set Hook-Up

Introduction to the Atari Computers and Peripherals 13
Illustration 1-4. Atari 800/Video Display Monitor Hook-Up
Plug-In Cartridge Hatches
Both the Atari 400 and 800 have a hatch on the top of the unit
which can be opened for the purpose of inserting a plug-in
cartridge (see Illustration 1-1). These cartridges contain ROM
memory (discussed later) on which programs are stored. These
programs may be games, applications programs, or even aBASIC
language
interpr ete r.
The Atari 400 allows the insertion of a single cart ridge while the
800 allows two cartridges to be inserted.
Computer Memory
Computer memory is measured in units known as bytes. A byte
is used to store a single character in the computer's memory.
Bytes are represe nted in units of measurement known as

14 User's Handbook to the Atari 400 / 800 Computers
kilobytes or K. 1K is the equivalent of 1024 bytes. Your Atari may
contain from 18 to 60K of memory (or 18,432 to 61,440 bytes).
Computer memory can be one of two different types; ROM or
RAM . ROM stands for read-only memory. ROM will hold the
data stored in it permanently. If the power to the Atari is shut off,
the information stored in ROM will remain there. ROM contains
the programs that are used to operate the Atari, and allow it to
interact with the user.
RAM stands for random-access memory* . The data stored in
RAM can be changed. Applications programs are often
transferred from diskettes or cassette to RAM .Any data stored in
RAM is lost when the Atari's power is turned off.
The Atari
400 includes 16K of RAM . Generally, it is not advisable
to attempt to expand the RAM capacity of an Atari 400.
The Atari 800 allows RAM to be expanded from 16K to as much as
48K. RAM is expanded on the Atari 800 by inserting additional
RAM plug-in modules underneath the unit 's top cover.
Expanding the Atari 's RAM is explained in more detail in
Chapter 2.
Atari 410 Program Recorder
Cassette tape can be used to store programs in RAM and then
transfer these programs back
into RAM at some later date. The
Atari
410 Program Recorder (as shown in Illustration 1-5) is
designed for use with the Atari computer . Approximate ly SDK or
51 , 200 bytes of data can be stored on a 30 minute cassette.
*Random access memory is a somewhat misleading term to
describe,
RAM, as most memory (including ROM), is randomly
accessed.

Introduction to the Atari Computers and Peripherals 15
Illustration 1-5. Atari 410 Program Recorder
Atari
810 Disk Drive
A disk drive is a much more efficient device for storing datathan
a cassette recorder. A disk
drive allows greater storage capacity,
quicker access to data, as well as fewer errors in data transfers.
The Atari
810 disk drive (as shown in Illustration 1-6) is designed
to be used with Atari computers. The Atari 810 uses single-sided
single density diskettes.
Diskettes which are designed to be written on only one side are
known as single sided (55) diskettes. Diskettes designed to be
written on both sides are known as double sided (OS) diskettes.
Density refers
to a diskette's recording format, which in turn
affects its capacity. Single-sided single density diskettes (as used
with the Atari 810) have a capacity of approximately 94K.

16 User's Handbook to the Atari 400 /800 Computers
Illustration 1-6. Atari 810 Disk Drive
The Atari 810 disk drive can only be used with the Atari 800
computer with a minimum of 16K of RAM.
Atari Printers
Atari produces three different printers; the 820 Printer, 822
Thermal Printer, and 825 Wide Carriage Printer.
The 820 and 822 Printers are connected to the Atari computer via
the I/ O Data Channel. The 825 Printer is connected to the Atari
computer with the 850 Int erface Module . The 850 Interface
Module can be used to connect printers other than the 825 to the
Atari.
Atari 850 Interface Module
The Atari 850 Interfa ce Module allows communications between

Intr oduction to the Atari Computers and Peripherals 17
the Atari computer and RS-232-C peripherals. We already
discussed the fact that the Atari 825 printer should be connected
via the Atari 850 Interface Module.
Another Atari peripheral that must be connected via the Atari
850 Interf ace Module is the Atari 830 Modem. The Atari 830
Modem allows your Atari to communicate with another terminal
also equipp ed with a modem over telephone lines.
The Atari 850 Interface Module is connected to the Atari
console. In turn, the peripherals are co nnect ed to the 850
Interfa ce Module. The 850 Interfa ce Module has 4 serial ports
and 1 parallel port, known as the printer port. The 850 Interface
Module has its own memory and processor and is programmed
from the Atari co mputer.
Game Controls
Three types of ga me control devices can be used with the Atari ;
joysticks,
paddl es, and keyboard controllers.
Software
Software can be
described as the instructions or programs that
cause the computer to operate. Several different classifications
of software exist for the performance of different functions.
Th ese ca n be classified as operat ing systems, languages, and
applications programs.
Operating
Systems
An operating system can be defined as a group of programs
which manage the overall operatio n of the computer. The
operating system performs system operations such as the
loading a nd unloadin g of data from cassette or diskette into
RAM a nd the display of operator keyboard entries on the video
screen.

18 User's Handbook to the Atari 400 / 800 Computers
The Atari's operating system is stored permanently in ROM .The
operating system is contained in a plug-in module in the .A.tari
800.
Languages
Programs are generally written in a high-level language that is
different from the instructions the computer uses . A program
known as an interpreter must be used to translate the high-level
language into a form that the computer can comprehend.
BASIC is the high-level language generally used with the Atari.
The Atari BASIC
interpreter is contained on a ROM cartridge
which can be plugged in under the hatch of either the Atari 400
or 800.
Applications Programs
Appl ications programs are those written to accompl ish aspecific
task. Examples
of applications programs are games, word
processing programs, financial forecasting programs, and
accounting programs. Generally, applications programs are
stored
on cassette or diskette and are transferred into RAM,
where the program is available to the computer.
Applications programs for the Atari can also be stored in a
permanent form on a ROM cartridge. This ROM cartridge can
be plugged in
underneath the hatch on the Atari. Examples of
ROM plug-in cartridges are shown in Illustration 2-4.