Atari 400 User manual

ERROR CODES
ERROR
CODE ERROR CODE MESSAGE
2
Memory In s ufficient
3
Va lue Error
4 Too
Many Vari ab l es
5
String Length Error
6
Out of Data Error
7
Number greater than 32767
8
Input Statement Error
9
Array or String DIM Error
10 Argument Stack Overflow
11 Fl oating Point Overflow /
Underflow Error
12
Line Not Found
13
No Matching FOR S ta tement
14
Line Too Long Error
15
GOSUB or FOR Lin e Del eted
16
RE TUR N Error
17
Garbage Error
18
In va lid String Character
Note : Th e foll owing are INPUT / OUTPU T er-
rors that resu lt du r in g th e u se of disk dri ves,
pr i nt e rs , or ot h er accessory d ev i ces . Furth er in-
fo
rm at ion is pro v id ed with th e auxilia ry hard -
ware .
19
LOAD program T oo Long
20
D ev ice Number Larger
21 L OAD File Error
128
BREAK Abort
129
IOCB
130
Nonexistent Device
131
IOCB Write Only
132 In va lid Comm a nd
133
D ev ic e or File not Op en
134
BAD IO CB ~umb er
135
IO CB R ea d On ly Error
136
EOF
137 Truncat ed R eco rd
138
De vice Tim eo ut
139
D evice NAK
140
Seri al Bus
141
C ursor Out of Ra ng e
ERROR
CODE ERROR CODE MESSAGE
142 Ser ial Bus Data Frame O verr un
143 Serial bus data fr ame checks um er ror
144 Dev i cP rlone e rr or
145 Read af t er write compare error
146 Funct ion not implemen ted
147 In sufficient RAM
160 Drive numb er er ror
161 Too many OPEN files
162 Disk full
163 U nrecov e rab le system data I/ 0 er ror
164 File number mi smatch
165 File name error
166 POINT d ata le ngth error
167 File l ocked
168 Command inva lid
169 Director y full
170 File not found
171 POINT i nvalid
For ex pl ana tion of Err or Mes sages see Appendix B.

TABLE OF MODES
AND SCREEN FORMATS
Vert. (Rows)
Vert. (Rows)
RAM
Gr.
Mode
Horiz.
Split
Full
II Of
Requir ed
Mod e Ty pe
(Column s)
Scre en
Screen
Colors
(B y t es )
0 TE
XT 40 -24 2
993
1
TEXT 20
20 24
5
513
2 TEXT
20
10
12 5
26 1
3 GRAPHI
CS 40 20
24 4 2
73
4 GR
AP HI CS 80
40
48 2
537
5 GRA PHI
CS
80
40 48
4 1
017
6
GR APHI CS 160
80 96 2
2025
7 GR APHI CS 160 80
96
4
3945
8
GRAPH ICS
320
1 60
1 92
1/2
7900
MODE, SET COLOR, COLOR TABLE
SETC OLOR
(a ex pl)
De fault
Mod e or C olor
C olo r
C
ol ors
Co nditi on Re
gi ster No.
(aex p)
DESCRIP TIO N AN D C OM MENTS
0 COLOR da ta -
LIGHT BLUE MODE 0 a nd
1 ac tu ally Cha
ra cter lum in ance ( sa m e color as bac kground )
DARK BLUE ALL
TEXT
2 de te rmines Back gro un d
WINDOWS
3 ch
arac t er to -
BLACK 4
be pl ot ted Borde1·
ORANGE
0 COLOR data
Cha1·acter
LI
GHT GREEN MODES 1 1
actually determine s Ch aracte r
DARK BLUE a
nd
2 cha
ra cter to be Ch aracter
RED 2 3 plott
ed
Char acte r
BL ACK (
Text Modes) 4
Backgro und , Bord er
ORANGE 0 1
Gr ap hics poin t
LIGHT GREEN MODES
3, 5, 1 2
Gra p hi cs poin t
DARK BLUE
and 7 2 3 Graph ics poi nt
(Four - co l or
3 -
BLACK
Mode s) 4 0 Gra
phics point (bac kgr ou nd defa ult ), Bo rder
ORANGE MODES 4 0 1
Grap hics point
an d 6 1 -
(Two- co lor 2 -
Mo de s) 3 -
BLACK 4 0 Gr
ap hi cs point ( bac k ground d efau lt ), Bor der
LIG HT GREEN 0 - -
DARK BLUE 1 1
Grap hi cs p oin t lumi nan ce (sa me col or as b ackgr ou nd)
MODE 8 2 0 Gr ap hi cs poi nt (ba ckgr o un d deliiUlt)
(1 Col or 3 -
BLACK 2 L um in ances)
4 Bor
der

CONTENTS
PREFACE vii
1 GENERAL INFORMATION
Terminolog y 1
Sp ec ial Not a tions U se d In Thi s Manual 3
Abbre v iation s Used In This M anual
4
Operating Modes
5
Spec ial Fun c tion K eys 5
Arithmetic Operator s 6
Operator Precedence
7
Built-In Fun c tions
7
Graphics 8
Sound and Games 8
W ra pa round and Key board Rollover 8
Error Messages 8
2 COMMANDS
BYE
9
CONT
9
E ND
9
LET 10
LIST
10
NEW
10
REM 10
RUN 11
S TOP
11
3 EDIT FEATURES
Scr ee n E diting
13
Control (CTRL) Key
13
Shift Key 13
Doub le K ey F un c ti ons
14
Cursor Control Keys
14
K ey s Used W ith CTRL Key
14
Keys Used W ith Shi ft K ey
14
Special Function Key s
14
Br e ak Ke y
14
Escape Key
14
4 PROGRAM STATEMENTS
FOR/NE XT /S TE P
15
GOSUBIRETURN
16
GOTO
17
I F/T H EN
18
Contents iii

ON/GOSUB
20
ON!GOTO
20
POP
20
RESTORE
21
TRAP
22
5 INPUT/OUTPUT COMMANDS
Input/Output Devices
23
CLOAD
24
CSAVE 24
DOS 25
ENTER
25
INPUT
25
LOAD
26
LPRINT
26
NOTE
26
OPEN/CLOSE
26
POINT
28
PRINT
28
PUT/GET 28
READ/DATA
28
SAVE
29
STATUS
29
XIO
30
Chaining Programs
30
6 FUNCTION LIBRARY
Arithmetic Functions
33
ABS
33
CLOG
33
EXP
33
INT
33
LOG
34
RND
34
SGN 34
SQR 34
Trigonometric Functions
34
ATN
34
cos
34
SIN
35
DEG/RAD
35
Special Purpose Functions
35
ADR
35
FRE
35
PEEK
35
POKE
35
USR
36
7 STRINGS
ASC
37
CHR$
37
iv
Contents

LEN
38
STR$
38
VAL
38
Str ing Ma nipul a tion s
39
8
ARRAYS AND MATRICES
DIM
41
CLR
43
9
GRAPHICS MODES AND COMMANDS
GRAPHICS
45
Graphics Modes
45
ModeO
46
Mo de s 1 and 2 46
Mod es 3, 5, and 7 47
Mod es 4 a nd 6
48
Mode8
47
COLOR
48
DRA W TO 48
LOCATE 48
PLOT 49
POSITION 49
PUT/GET
49
SETCOLOR
50
XIO ( Sp e cial Fill Application) 54
A ss igning Colors to Tex t Modes
54
Gra ph ic s Co nt r ol C har acter s 56
10
SOUND AND GAME CONTROLLERS
SOUND
57
PADDLE
59
PTRIG
59
ST ICK
59
STRIG
60
11 ADVANCED PROGRAMMING TECHNIQUES
Mem ory Con servat ion
61
Programm i ng In M ac hin e La ngu age
63
APPENDIX A
BASIC RESERVED WORDS
A-1
APPENDIX B
ERROR MESSAGES
B-1
APPENDIX C
ATASCII CHARACTER SET
WITH DECIMAL /
HEXADECIMAL LOCATIONS
C-1
APPENDIX D
ATARI 400 / 800
MEMORY MAP
D-1
Conte nts V

APPENDIX E DERIVED FUNCTIONS
E-1
APPENDIX F
PRINTED VERSIONS OF
CONTROL CHARACTERS F-1
APPENDIX G GLOSSARY G-1
APPENDIX H USER PROGRAMS
H-1
APPENDIX I MEMORY LOCATIONS 1-1
INDEX
117
vi Conte nt s

PREFACE
This manual assumes the user has read the Atari BASIC -A Self-Teaching
Guide or some other book on BASIC. This manual is not intended to "teach"
BASIC. It is a reference guide to the commands, statements, functions, and
special applications of Atari® BASIC.
The programs and partial programming examples used in this manual are
photostats oflistings printed on the Atari 820™ Printer. Some of the special sym-
bols in the Atari character set do not appear the same on the printer; e.g., the
clear screen symbol '~" appears as a " } ". The examples in the text were
chosen to illustrate a particular function- not necessarily "good" programming
techniques.
Each of the sections contains groups of commands, functions, or statements
dealing with a particular aspect of Atari BASIC. For instance, Section 9 contains
all the statements pertaining to Atari's unique graphics capabilities. The appen-
dices include quick references to terms, error messages, BASIC keywords,
memory locations, and the AT ASCII character set.
As there is no one specified application for the Atari Personal Computer System,
this manual is directed at general applications and the general user. Appendix H
contains programs that illustrate a few of the Atari system's capabilities.
Preface vii

TERMINOLOGY
1
GENERAL
INFORMATION
This section explains BASIC terminology, special notations , and abbre v iation s
used in this manual, and the special keys on the AT ARI 400™ and AT ARI 800 ™
Personal Computer Systems keyboard . It also points to other sections where
BASIC commands deal with specific applications.
BASIC: Beginner's All-purpose Symbolic Instruction Code.
BASIC Keyword: Any reser v ed word "legal " in the BASIC language. May be
used in a statement , as a command, or for any other purpose. (See Appendi x A
for a list of all "reserved words" or keywords in AT ARI BASIC.)
BASIC Statement: Usually begins with a keyword , like LET, PRINT, or
RUN.
Constant: A constant is a value expressed as a number rather than represented
by a variable name . For example, in the statement X = 100 , X is a v ariable and
100 is a constant. (See Variable.)
Command String: Multipl e commands (or pr o gr am st at em e nt s) pl ac ed on th e
same numbered line separated by colons.
Expression: An e xpression is i my le gal c ombin a tion of va riables , c onstan ts,
operators, and functions used together to compute a value. Expressions can be
either arithmetic, logical, or string .
Function: A function is a computation built into the computer so that it can be
called for by the user 's program. A function is NOT a statement ; it is part of an
expressi o n. It is r ea lly a subroutin e used to c omput e a va lu e which is then
"returned" to the main program when the subroutine returns. COS (Cosine),
RND (random), FRE (unused memory space), and INT (integer ) are ex amples of
functions . In man y cases th e v alue is s impl y as sign ed to a va riabl e (stored in a
var iable) for lat er use. In other ca s es it may be print ed out on th e scr een im-
mediately. See Section 6 for more on functions. Examples of functions as they
might appear in programs are:
10 PF.:HH F.l[l( 0)
( print ou t the random
numb er ret urn ed)
(add
the value re-
r et urn ed to 100 a nd
sto re the to ta l in
variable
X)
General In fo r ma tion 1

2 Gene ral Inf orm at ion
Logical Line: A logical line consists of one to three physical lines, and is ter-
minated either by a l;i#iii;lli or automatically when the maximum logical line
limit is reached. Each numbered line in a BASIC program consists of one logical
line when displayed on the screen. When entering a line which is longer than
one physical line, the cursor will automatically go to the beginning of the next
physical line when the end of the current physical line is reached . Ifi@ii!;lllis
not entered, then both physical lines will be part of the same logical line.
Operator: Operators are used in expressions. Operators include addition (+),
subtraction (- ), multiplication ( * ), division (/), exponentiatinn (A), greater than
(>), less than (<),equal to (= ) ,greater than or equalt o(>=), less than or equalto
( <,::: ), and not equal to (< > ). The logical keywords AND, NOT and OR are also
operators. The + and - operators can also be used as unary operators; e. g., -3.
Do not put several unary operators in a row; e.g.,--3 , as the computer will in-
terpret it incorrectly.
Physical Line: One line of characters as displayed on a television screen.
String: A string is a group of characters enclosed in quotation marks.
"ABRACADABRA" is a string. So are " ATARI MAKES GREAT COMPUTERS"
and "123456789" . A string is much like a constant, as it too, may be stored in a
variable . A string v ariable is different, in that its name must end in the
character$. For example, the string "AT ARI 800" ma y be assigned to a variable
called A$ using (optional) LET like this:
10 LET A$="ATAF.J 8H0"
OR (note quot
ation marks)
(LET is optional; the
quotes are required.)
Quotation marks may n ot be used within a string. However , the closing quota-
tion can be omitted if it is the last character on a logical line. (See Section 7 -
STRINGS).
Variable: A variable is the name for a numerical or other quantity which may
(or may not) change. Variable name s ma y be up to 120 characters long.
However, a variable name must start with an alphabetic letter, and ma y contain
only capital letters and numerical digits. It is ad v isable not to use a ke yw o rd as a
variable name or as the first part of a va riable name as it m ay not be inte r preted
correctly. Examples of s toring a value in a vari a ble:
LETC 123Dt..J8= 1. 234
LETI . .JARIABLE112=267 . 543
LETA=1
LET F5TH=6 .5
LET TH J::;HO = 59 . :: : £19
Note: LET is optional and may be omitted)
Variable Name Limit: ATARI BASIC limits the user to 128 variable names .To
bypass this problem , use individual elements of an arra y instead of having
separate vari a ble names. BASIC keeps all refe r ence s to a variabl e which has
been deleted from a program , and the name still remains in the variable name
table.