Sinclair ZX81 User Manual

Sinclair ZX81 BASIC Programming
by Steven Vickers
Second Edition 1981
Copyright 1980 Sinclair Research Limited
Front cover illustration by John Harris of Young Artists,
specially comissioned by Sinclair Research Limited.

Sinclair ZX81 Specifications

General

Processor	Zilog Z80A
Processor Speed	3.25 MHz
ROM	8 KB
Input	Membrane keyboard
Storage	Cassette tape
Power Supply	9V DC
Dimensions	167 mm x 40 mm x 175 mm
Release Year	1981
Manufacturer	Sinclair Research
Weight	350 g
Operating System	Sinclair BASIC
RAM	1 KB
Ports	TV out, expansion port
Display	Television (RF modulator output)

Summary

Chapter 1 - Setting up the ZX81

Chapter 2 - Telling the computer what to do

Chapter 3 - A History lesson

Chapter 4 - The Sinclair ZX81 as a calculator

Chapter 5 - Functions

Chapter 6 - Variables

Chapter 7 - Strings

Chapter 8 - Computer programming

Chapter 9 - More computer programming

Chapter 10 - If...

Chapter 11 - The character set

Chapter 12 - Looping

Chapter 13 - Slow & fast

Chapter 14 - Subroutines

Chapter 15 - Making your programs work

Chapter 16 - Tape storage

Saving a program

Instructions for saving a program onto cassette tape.

Loading a program with a name

Steps to load a named program from tape.

Loading a program without a name

Procedure to load the first available program from tape.

Chapter 17 - Printing with frills

Chapter 18 - Graphics

Chapter 19 - Time & motion

Chapter 20 - The ZX81 Printer

Chapter 21 - Substrings

Chapter 22 - Arrays

Chapter 23 - When the computer gets full

Chapter 24 - Counting on your fingers

Chapter 25 - How the computer works

Chapter 26 - Using machine code

Restrictions on USR routines

Lists restrictions for using USR routines with machine code.

Machine code in memory

Discusses safe places to store machine code within memory.

Chapter 28 - The system variables

Appendix C - The ZX81 for those that understand BASIC

General

Covers BASIC idiosyncrasies, keywords, functions, strings, character set, and PEEK/POKE.

Speed

Explains the two speeds: compute & display mode and fast mode.

The keyboard

Details keyboard modes (K, L, graphics) and key functions.

The screen

Describes the screen layout, display areas, and keyboard input display.