Telling the computer what to do
How to type things in to the computer
, 
,
RUBOUT,
NEWLINE
CHAPTER
1
Setting up the ZX81
& how to use this manual,
whether or not you know BASIC.
CHAPTER
2
Telling the computer
what to do
How to type things in to
the computer
, ,
RUBOUT,
NEWLINE
CHAPTER
3
A History lesson
CHAPTER
4
The Sinclair ZX81 as
a pocket calculator
Statement: PRINT
with commas & semicolons
Operations: +, -, *, /,
**
Expressions & scientific
notation
CHAPTER
5
Functions
Statement: RAND
Functions: ABS, SGN,
SIN,
COS,
TAN, ASN, ACS, ATN,
LN,
EXP,
SQR, INT, PI, RND, FUNCTION
CHAPTER
6
Variables
Statements: LET,
CLEAR
Simple numeric variables
CHAPTER
7
Strings
Operation: + (for strings)
Functions: LEN, VALSTR$
Strings, simple string variables
CHAPTER
8
Computer programming
Statements: RUN,
LIST
Programs
Editing programs using 
, 
& EDIT
CHAPTER
9
More computer programming
Statements: GOTO,
CONT,
INPUT,
NEW, REM, PRINT
STOP in INPUT
data
BREAK
CHAPTER
10
If...
Statements: IF, STOP
Operations: =, <, >,
<=,
>=,
<>,
AND,
OR
Function: NOT
CHAPTER
11
The character set
Functions: CODE,
CHR$
The character set is thoroughly
non-standard
GRAPHICS
CHAPTER
12
Looping
Statements: FOR,
NEXT,
TO,
STEP
CHAPTER
13
SLOW & FAST
Statements: SLOW,
FAST
The ZX81 operates at two
speeds: one neat, the other fast.
CHAPTER
14
Subroutines
Statements: GOSUB,
RETURN
CHAPTER
15
Making your programs
work
Flowcharts & debugging
CHAPTER
16
Tape storage
Statements: SAVE,
LOAD
CHAPTER
17
Printing with frills
Statements: CLS,
SCROLL
PRINT items: AT,
TAB
CHAPTER
18
Graphics
Statements: PLOT,
UNPLOT
CHAPTER
19
Time & motion
Statement: PAUSE
Function: INKEY$
CHAPTER
20
The ZX81 Printer
Statements: LPRINT,
LLIST,
COPY
CHAPTER
21
Substrings
Slicing, using TO
CHAPTER
22
Arrays
Statement: DIM
CHAPTER
23
When the computer gets
full
Odd things happen
CHAPTER
24
Counting on your fingers
Binary & hexadecimal
counting
CHAPTER
25
How the computer works
What the individual chips
do
Statement: POKE
Function: PEEK
CHAPTER
26
Using machine code
Statement: NEW
Function: USR
CHAPTER
27
Organization of memory
CHAPTER
28
System variables
APPENDICES
A
The character set
B
Report codes
C
The ZX81 for those that understand BASIC