Watts L., Wharton M. Usborne introduction to Machine Code for Beginners

This book is a simple, step-by-step guide to learning to write programs and games in machine code for Z80 and 6502 CPUs (microcomputers ZX81, ZX Spectrum, Timex 2000, Timex 1000, VIC 20, BBC Micro, Atari, Oric, Commodore 64) No OCR layer available.
Usborne Publishing Ltd., 1983. - 51 p. ISBN: 0-86020-735-84 What is machine code?
6 Getting to know your computer
8 The computer's memory
11 Hex numbers
12 Peeking and poking
14 Inside the CPU
16 Giving the CPU instructions
18 Translating a program into hex
20 Finding free RAM
23 Loading and running a program
27 Adding bytes from memory
28 Working with big numbers
29 The carry flag
30 Big number programs
32 Displaying a message on the screen
35 Jumping and branching
38 Screen flash program
40 Going further
41 Decimal/hex conversion charts
42 Z80 mnemonics and hex codes
45 6502 mnemonics and hex codes
46 Machine code words
48 Index