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Posted: 01:42pm 16 Jul 2026

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Free Pico Computer 3 if you know python/micropython and are prepared to do some serious testing and proof reading

I've written a book about learning to use Micropython on the Pico Computer 3. I need someone to help proof read this in detail and test all the example programs.

If you want to help let me know

For info, the contents of the book are as follows:

Quote Chapter 1 — What is the Pico Computer 3? 1
A computer that boots straight into a language . . . . . . . . . . . . . . . . . 1
A tour of the hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
What is a program? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Why Python? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
How to use this book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Chapter 2 — Getting started: flashing and first boot 6
What you will need . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Step 1 — Get the firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Step 2 — Flash the firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Step 3 — Wire up and switch on . . . . . . . . . . . . . . . . . . . . . . . . . 7
Step 4 — Prove it’s alive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Step 5 — Tell it about your keyboard . . . . . . . . . . . . . . . . . . . . . . . 8
If something doesn’t work . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Chapter 3 — Your first conversation with Python 11
The world’s most overqualified calculator . . . . . . . . . . . . . . . . . . . . 11
Two kinds of division . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Words, not just numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
print(), and who is talking . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Breaking it on purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Working comfortably . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Borrowing more mathematics . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Chapter 4 — Finding your way around: files and the shell 17
Two drives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Where am I? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Making some files to practise on . . . . . . . . . . . . . . . . . . . . . . . . . 18
Folders, copies, and moves . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Wildcards: acting on many files at once . . . . . . . . . . . . . . . . . . . . . 19
The SD card and your PC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
fm — the file manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Chapter 5 — Writing real programs: the editor 22
Your first program file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Getting comfortable in the editor . . . . . . . . . . . . . . . . . . . . . . . . . 23
When programs go wrong: your first debugging workflow . . . . . . . . . . . 23
A program with rhythm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Getting programs in from a PC . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Making a program run at switch-on . . . . . . . . . . . . . . . . . . . . . . . 25
Where you now stand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Chapter 6 — Variables, numbers and text 27
Naming things . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Three kinds of value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
input(): programs that listen . . . . . . . . . . . . . . . . . . . . . . . . . . 29
f-strings: sentences with values inside . . . . . . . . . . . . . . . . . . . . . . 29
Project: a program that chats back . . . . . . . . . . . . . . . . . . . . . . . . 30
Project: a units converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Chapter 7 — Making decisions: if 32
Questions with yes/no answers . . . . . . . . . . . . . . . . . . . . . . . . . . 32
if: the fork itself . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
else and elif: covering every road . . . . . . . . . . . . . . . . . . . . . . . 33
and, or, not . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Secrets: the random toolbox . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Project: the guessing game, round one . . . . . . . . . . . . . . . . . . . . . 35
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Chapter 8 — Repeating yourself: loops 37
while: repeat as long as this is true . . . . . . . . . . . . . . . . . . . . . . . 37
The forever loop, on purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
The rematch: finishing the guessing game . . . . . . . . . . . . . . . . . . . . 38
for and range(): when you know how many . . . . . . . . . . . . . . . . . . . 39
Loops you can see . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
break and continue: steering mid-loop . . . . . . . . . . . . . . . . . . . . . . 41
Project: the times-table dojo . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Chapter 9 — Turtle graphics: loops you can see 43
First steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
The square, and the moment of the chapter . . . . . . . . . . . . . . . . . . . 44
Every polygon at once . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Stars: when the turtle overshoots . . . . . . . . . . . . . . . . . . . . . . . . 45
Spirals: let the steps grow . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Nested loops: the flower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Project: the spirograph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Chapter 10 — Collections: lists, tuples and dictionaries 49
Lists: an ordered, changeable crowd . . . . . . . . . . . . . . . . . . . . . . . 49
Walking a list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Slices: a piece of the list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Sorting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Tuples: values that belong together . . . . . . . . . . . . . . . . . . . . . . . 53
Dictionaries: look things up by name . . . . . . . . . . . . . . . . . . . . . . 54
Choosing your container . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Project: the high-score table . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Project: the quiz, grown up . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
What you now hold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Chapter 11 — Functions: building your own commands 58
def: teaching, then telling . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Parameters: one function, a family of jobs . . . . . . . . . . . . . . . . . . . . 59
return: functions that answer . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Scope: the sealed room . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
The refactor: chapter 9, four lines at a time . . . . . . . . . . . . . . . . . . . 61
Project: your shapes library . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
What you now hold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Chapter 12 — Strings and files 66
Strings are sequences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
String methods: the text workshop . . . . . . . . . . . . . . . . . . . . . . . . 66
Split and join: strings ↔ lists . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Files, the full story . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Project: the diary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Project: scores that survive — a library . . . . . . . . . . . . . . . . . . . . . 69
Jumping around: seek, tell and fixed-length records . . . . . . . . . . . . . . 71
One more gift: sort meets your functions . . . . . . . . . . . . . . . . . . . . 72
What you now hold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Chapter 13 — When things go wrong: errors and debugging 74
What an exception actually is . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
try: the safety net . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Catch precisely . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Hearing what happened: as e . . . . . . . . . . . . . . . . . . . . . . . . . . 76
raise: sounding the alarm yourself . . . . . . . . . . . . . . . . . . . . . . . 76
The rogues’ gallery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Hunting bugs: the other half . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Project: the bulletproofing pass . . . . . . . . . . . . . . . . . . . . . . . . . 78
What you now hold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Chapter 14 — Objects: a gentle introduction to classes 81
The problem classes solve . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
The blueprint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Methods: the rules move in . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
print(h) — teaching your object to speak . . . . . . . . . . . . . . . . . . . . 83
Objects in collections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Project: the character sheet, playable . . . . . . . . . . . . . . . . . . . . . . 84
Project: the bank account . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
You’ve been here all along . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
What you now hold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

Chapter 15 — The screen up close 88
How the picture actually works . . . . . . . . . . . . . . . . . . . . . . . . . . 88
The four screens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
The map: coordinates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Colour: mixing light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
The toolbox . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Words on the screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Project: the poster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Project: the living clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Chapter 16 — Bitmap images and sprite sheets 95
Putting a picture on the screen . . . . . . . . . . . . . . . . . . . . . . . . . . 95
The colour squeeze, and dithering . . . . . . . . . . . . . . . . . . . . . . . . 95
Transparency, part one: PNG alpha . . . . . . . . . . . . . . . . . . . . . . . 96
Sprite sheets: pictures held in memory . . . . . . . . . . . . . . . . . . . . . 96
hdmi.blit: the universal rectangle mover . . . . . . . . . . . . . . . . . . . . 97
An asset pipeline with no PC . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Project: the photo frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

Chapter 17 — Smooth motion: buffers and the overlay 101
Stage 0: the smear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Stage 1: the eraser — and the blink . . . . . . . . . . . . . . . . . . . . . . . 102
Stage 2: vsync — drawing between the frames . . . . . . . . . . . . . . . . . 102
Stage 3: the off-screen buffer — frames built in private . . . . . . . . . . . . . 103
The overlay: motion without redrawing the world . . . . . . . . . . . . . . . . 105
The scenery cheat: blit-scrolling . . . . . . . . . . . . . . . . . . . . . . . . . 106
Choosing your weapon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Project: the immortal screensaver . . . . . . . . . . . . . . . . . . . . . . . . 107
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

Chapter 18 — Sprites 110
A small loan from chapter 21 . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Sprites from nowhere: grab . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Collisions: the engine speaks . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
Project: the shooting gallery . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

Chapter 19 — Tile maps: big worlds from small pieces 117
Forging the tileset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
A first map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
The camera: worlds beyond the screen . . . . . . . . . . . . . . . . . . . . . 119
Walking on the world . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Project: the island . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

Chapter 20 — Sound and music 125
Playing files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
A one-minute physics lesson . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
tone(): two sine waves, endless patience . . . . . . . . . . . . . . . . . . . . 126
Project: the tune player . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
sound(): the four-voice synthesiser . . . . . . . . . . . . . . . . . . . . . . . 127
Project: the sound-effects library . . . . . . . . . . . . . . . . . . . . . . . . . 127
Tracker music: the game soundtrack . . . . . . . . . . . . . . . . . . . . . . 129
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

Chapter 21 — Reading the player: keyboard, mouse and touch 131
keydown(), the whole truth . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
keyboard.on_key(): the doorbell . . . . . . . . . . . . . . . . . . . . . . . . . 132
The mouse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
The touch panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Project: paint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
Interlude: a stopwatch for the machine . . . . . . . . . . . . . . . . . . . . . 135
Project: the reaction duel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

Chapter 22 — Anatomy of a game 138
The loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Frame timing: the metronome . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Game state: one variable, whole architecture . . . . . . . . . . . . . . . . . . 139
Project: Pong, part one — the rally . . . . . . . . . . . . . . . . . . . . . . . . 140
Project: Pong, part two — the match . . . . . . . . . . . . . . . . . . . . . . . 142
What you now hold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

Chapter 23 — Breakout 147
The whole game . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
The wall is a list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
Which face did the ball hit? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
The economy: lives, levels, ramp . . . . . . . . . . . . . . . . . . . . . . . . . 151
Someone else’s Breakout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

Chapter 24 — Asteroids: vectors, crowds and particles 154
The two lines of trigonometry . . . . . . . . . . . . . . . . . . . . . . . . . . 154
Stage one: flight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
Stage two: the game . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

Chapter 25 — The adventure: NPCs, dialogue and saved worlds 164
The forge, extended . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
The game . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
The just-pressed pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
Dialogue is a state, and the words are data . . . . . . . . . . . . . . . . . . . 171
The save file: derive, don’t store . . . . . . . . . . . . . . . . . . . . . . . . . 171
What this chapter proves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172

Chapter 26 — Polish: the last ten percent 173
The juice lab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
The component: three-initial entry . . . . . . . . . . . . . . . . . . . . . . . . 176
Difficulty: the curve is the game . . . . . . . . . . . . . . . . . . . . . . . . . 178
Playtesting: the mum test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
The shippable checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179

Chapter 27 — Building apps: the GUI toolkit 180
The model: describe, then poll . . . . . . . . . . . . . . . . . . . . . . . . . . 180
The pointer: pccursor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
The catalogue, briskly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
Project: the calculator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
Project: the settings screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189

Chapter 28 — Time and schedules: the real-time clock 190
The three clocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
Anatomy of a time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Date arithmetic: mktime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Project: the kitchen timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Project: the bedside alarm clock . . . . . . . . . . . . . . . . . . . . . . . . . 193
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196

Chapter 29 — Going online: Wi-Fi and the internet 197
Connecting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
The first fruit: atomic time . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
Asking the web a question . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
JSON: the internet’s data, in a familiar costume . . . . . . . . . . . . . . . . . 198
Project: the weather panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
A taste of MQTT: machines talking to machines . . . . . . . . . . . . . . . . . 201
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202

Chapter 30 — Numbers at speed: the maths lab 203
plot(), properly this time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
Arrays: the loops vanish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
Where the rest lives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
The pcmath bench . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
Project: the maths lab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208

Chapter 31 — Talking to the outside world: GPIO 209
The header map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
Output: your first electron . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
Input: buttons, and why pins float . . . . . . . . . . . . . . . . . . . . . . . . 210
Analogue: the knob . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
PWM: pretending, very fast . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
I2C and the QWIIC socket: the module ecosystem . . . . . . . . . . . . . . . 212
Project: the paddle controller . . . . . . . . . . . . . . . . . . . . . . . . . . 213
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214

Chapter 32 — Doing several things at once 216
The tap on the shoulder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
Pin interrupts: the doorbell . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
The promise kept: waking to the DS3231 . . . . . . . . . . . . . . . . . . . . 218
The watchdog: for machines left alone . . . . . . . . . . . . . . . . . . . . . . 219
The rules of the tap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
asyncio: the polite jugglers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
Project: the game that downloads . . . . . . . . . . . . . . . . . . . . . . . . 220
A note on threads, and why not . . . . . . . . . . . . . . . . . . . . . . . . . . 223
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223

Chapter 33 — Performance and memory 225
The stopwatch, made permanent . . . . . . . . . . . . . . . . . . . . . . . . . 225
Why Python costs what it costs . . . . . . . . . . . . . . . . . . . . . . . . . . 226
The real ladder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
Memory: the other resource . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
The worked session: a swarm, tuned . . . . . . . . . . . . . . . . . . . . . . . 229
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230

Chapter 34 — The system itself 231
The five seconds after the switch . . . . . . . . . . . . . . . . . . . . . . . . . 231
The geography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
The backup habit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
Trust, verified: the test suite . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
Reading the machine’s own source . . . . . . . . . . . . . . . . . . . . . . . . 233
Where the road goes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
The end of the course . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235

Appendix A — The cheat sheet 236
The shell (chapter 4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
fm keys (chapter 4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
The editor, pye (chapter 5) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
The prompt (chapters 3, 8) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
Screen (chapters 15–17) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
Input (chapters 18, 21) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
Sound (chapter 20) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
Games (chapters 18, 19, 22) . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
Time & system (chapters 28, 34) . . . . . . . . . . . . . . . . . . . . . . . . . 238
GPIO (chapter 31) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
The collars (never forgotten) . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

Appendix B — Coming from MMBasic 239
Language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
Files and the shell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
Screen and graphics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Input, sound, time, events . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242

Appendix C — The modules, one paragraph each 244
The board’s own . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
The standard library (the ones this book used) . . . . . . . . . . . . . . . . . 245
Your own shelf (built through the book) . . . . . . . . . . . . . . . . . . . . . 245

Appendix D — Hardware reference 246
The machine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
Sockets, switches and buttons . . . . . . . . . . . . . . . . . . . . . . . . . . 246
Flashing (chapter 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
The I/O header . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
Reserved pins (unavailable to machine.Pin) . . . . . . . . . . . . . . . . . . . 247
Screen modes (chapter 15) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248

Appendix E — Python, the taught subset 249
Values and operators (3, 6, 7) . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
Strings (3, 6, 12) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
Collections (10) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
Control flow (7, 8) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
Functions (11) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
Classes (14; appendix I for more) . . . . . . . . . . . . . . . . . . . . . . . . . 250
Errors (13) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
Files (12) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
Modules (11) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
Built-ins the book used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
MicroPython differences met in this book . . . . . . . . . . . . . . . . . . . . 251

Appendix F — Challenge hints 252

Appendix G — Glossary 254

Appendix H — Troubleshooting 256
Power and boot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256
Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256
Keyboard, mouse, touch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
Files and SD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258
Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258
Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258
When all else fails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259

Appendix I — Classes beyond the cottage 260
Inheritance: blueprints from blueprints . . . . . . . . . . . . . . . . . . . . . 260
Custom exceptions: inheritance you’ll actually use . . . . . . . . . . . . . . . 261
__repr__: the other voice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
Operator hooks: teaching + and < your types . . . . . . . . . . . . . . . . . . 262
__len__ and __getitem__: passing for a list . . . . . . . . . . . . . . . . . . . 263
CONTENTS x
Class attributes: one value, all instances . . . . . . . . . . . . . . . . . . . . 263
@property: computed attributes . . . . . . . . . . . . . . . . . . . . . . . . . 264
@classmethod and @staticmethod . . . . . . . . . . . . . . . . . . . . . . . . . 264
Privacy: the underscore treaty . . . . . . . . . . . . . . . . . . . . . . . . . . 265
Duck typing: the interface is the behaviour . . . . . . . . . . . . . . . . . . . 265
When not to use any of this . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
Where to read further . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266

Volhout
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Location: Netherlands
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Posted: 01:59pm 16 Jul 2026

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Peter,

I do not qualify (haven't the faintest idea about python), but I volunteer in reading the book, so I can learn about uPython. But ... next 3 weeks I will be on holiday.
That disqualifies me completely.

Volhout
Edited 2026-07-17 00:00 by Volhout

PicomiteVGA PETSCII ROBOTS

Bleep

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Posted: 05:09pm 16 Jul 2026

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I know nothing about Python, but am happy to read your book for you, see what I can pick up. (not on holiday for the foreseable future).
Kevin.

LeoNicolas

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Posted: 05:26pm 16 Jul 2026

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I like Python and I already have a project in mind to run on your new Pico Computer 3 with Micropython. I will be happy to read your book as well

Is it possible to have a desktop version of the environment, like MMB4W or MMB4L, to test my projects?

homa

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Posted: 05:59pm 16 Jul 2026

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I’m not sure how quickly this needs to be done, but I’d be happy to do it without the Pico Computer 3. I won't be ordering mine until August though. My son knows Python, and I’ll encourage him to get involved. :-) I’ll learn it myself in the process. Please feel free to send me the PDF or book via private message or email.

matherp
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Posted: 07:51pm 16 Jul 2026

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pm me with an email address and I'll send you all the book

zeitfest
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Posted: 11:52pm 16 Jul 2026

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It would be better to use Claude (Anthropic) to test your python programs, maybe that has been done already ? That would allow a systematic test against specified version(s) of Python. There are also extensive proof reading apps that can be used.

matherp
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Posted: 06:30am 17 Jul 2026

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Quote It would be better to use Claude (Anthropic) to test your python programs,

Many of them rely on the specific H/W of the Pico Computer 3 and the specific capabilities of the Pico Computer 3 firmware
Edited 2026-07-17 16:45 by matherp

LeoNicolas

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Posted: 09:50am 17 Jul 2026

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I can test it as soon as I have my pico3 board. I think I will have the board in August

matherp
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Posted: 09:52am 17 Jul 2026

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I'm working on a PC3 emululator for the PC (Linux or WSL) will post progress as/if it occurs

Note: I've emailed the book to those who asked for it. If you haven't received it check spam
Edited 2026-07-17 20:30 by matherp

lizby
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Posted: 02:30pm 17 Jul 2026

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I would also like to have the book, please.

PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on FOTS

matherp
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Posted: 04:03pm 17 Jul 2026

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No problem - pm me your email address

scruss
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Posted: 08:22pm 17 Jul 2026

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MicroPython programmer for about a decade, used to proof-read dictionaries. Would I qualify?

matherp
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Posted: 09:00pm 17 Jul 2026

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Quote MicroPython programmer for about a decade, used to proof-read dictionaries. Would I qualify?

Definitely, send me your snail-mail address and I'll get one in the post. Away from home at the moment so will be Wednesday before it hits the mail.

LeoNicolas

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Posted: 11:16pm 17 Jul 2026

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matherp said I'm working on a PC3 emululator for the PC (Linux or WSL) will post progress as/if it occurs

Note: I've emailed the book to those who asked for it. If you haven't received it check spam

Hi Peter

I haven't received the email. I have checked the spam folder

zeitfest
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Posted: 01:08am 18 Jul 2026

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This might help for some of it - micropython tests

matherp
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Posted: 07:17am 18 Jul 2026

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Quote I haven't received the email. I have checked the spam folder

Definitely in my sent folder. I've sent it again from a gmail address - see if that works

matherp
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Posted: 07:21am 18 Jul 2026

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Note

The Pico Computer has now been claimed. But if anyone else wants the manual drop me a PM with your email address

Bryan1

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Posted: 09:10am 18 Jul 2026

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Well I got to the end of chapter 7 just now and gotta say my PICO 3 computer is getting python on tomorrow

So the next part is sourcing that wifi and psram chip so my board can be complete.

Regards Bryan

Mixtel90

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Posted: 09:42am 18 Jul 2026

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From looking at the Contents I reckoned that Chapter 6 or just possibly 7 would be about as far as I could manage. I've never managed to get any further with Python really - not and understand what I was doing anyway.

Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs

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