Code Like It's 198x

This book will lie to you. On purpose.

Every explanation of how a computer works is a simplification. This book gives you the simple version first, lets you use it, and then shows you exactly where it stops being true. Each of those moments takes you a step closer to what the machine is really doing.

It does it on one small computer from 1982, the ZX Spectrum, where nothing is hidden. You’ll find out:

• what really happens when you type RUN
• why the Spectrum’s picture is stored in such a strange order
• why its colour comes in 8 × 8 squares, and how games turned that limit into a style
• why the same code runs at different speeds in different parts of memory
• how a computer with no sound chip makes sound, and loads programs from tape

Along the way, the Spectrum is set beside its neighbours, from the ZX81 and the Commodore 64 to the Amiga and the NES, and finally a Raspberry Pi 4, to show that the same questions still work on the computers we use today.

You don’t need to know how to program. Every program in the book has been run, and every picture of a screen comes from the program running, so you can read the code and see exactly what it does.

I’m Steve Hill. The Spectrum was the computer I started out with in the 1980s. Now I make games, tools and teaching material under the name Phosphene, and I run Code198x, which teaches programming on the computers of the 1980s. I wrote this book for anyone who’s ever wondered what the layers are hiding.

Read Part 1 free at code-like-its-198x.phosphene.uk