A real computer from 1981 — and the secret inside every computer & phone

MEET THE MICROTRONIC!

It’s a tiny computer you command by hand — no mouse, no apps, just a keypad and a glowing display. You type in instructions one at a time… and YOU become the programmer! 🤖
“Buschi” & the Microtronic — ready to play!
4bits — it thinks in tiny numbers
16little number boxes (registers)
3digits = one instruction
1981made in Germany by Busch

💡 BINARY — just 0 and 1

Inside every computer are millions of tiny switches. A switch is either ON = 1 or OFF = 0. That’s the whole alphabet computers use!

0
1
0
1
Four switches spell 0101 — that means 5!
0000=0   0001=1   0010=2   0011=3   0100=4
0101=5   0110=6   0111=7   1000=8   1001=9

Try it: can you count to 5 on one hand, using each finger as a switch? ✋

🔢 HEX — a shortcut for 0–15

Four switches make 16 different values (0–15). Writing 1111 is long, so we give each value one symbol — after 9 we keep going with letters!

101112131415
ABCDEF

So F means 15! This is called hexadecimal (“hex”). The Microtronic shows everything in hex — and each number box holds one hex digit, 0 to F.

💻 WRITE YOUR FIRST PROGRAM!

Every Microtronic instruction is just 3 hex digits. This is machine code — the real language your phone, game console and every computer secretly run, billions of times a second. Try this:

1 5 1→put the number 5 into Box 1
5 3 1→add 3 to Box 1
🎉 Box 1 now holds 5 + 3 = 8 — you just programmed a computer!
⚡ If a box ever goes past F (15), the Carry light blinks — that’s how computers count to really big numbers, one nibble at a time.

🌐 WHY IT MATTERS

The Microtronic is slow enough that you can see every step a computer takes. Learn it, and you understand what’s really happening inside all computers — phones, laptops, robots, spaceships. 🚀

It’s 4-bit and does only a few instructions per second… but it works exactly like the big machines, just one tiny move at a time.

🔨 Want to become a programmer? Build your own!

Ask a grown-up to help you build the Microtronic Phoenix — a modern kit that even runs the real 1981 program chip. It’s free and open-source: github.com/lambdamikel/microtronic-phoenix

Need parts or help assembling it? Have a parent email me: miacwess [at] gmail [dot] com ✉️
(shown this way on the web to keep the spam-bots away — the printable PDF has the real address)