subprograms with parameters
Zuse planned procedures that take and return values — the shape every later function signature followed, decades before the hardware could run it.
§ 02 — Eras · 1945
Plankalkül
the first programming language ever designed — and the last to run
Left: era context, features, and the 101 hello. Right: 3 deeper 201 lessons, the factorial specimen, and where Plankalkül lives today — each column scrolls on its own.
The problem it solves
Programming a binary machine meant re-wiring it by hand. Zuse wanted a notation in which engineers could write computation itself — plans, not plugboards.
The problem it carries
It existed only on paper: unpublished, unimplemented, unrun until 2000 — a full language that influenced almost nothing.
Key features
- assignment
- Values bind to names with a single arrow, so a program reads as a sequence of plans instead of memory addresses.
- subprograms
- Reusable procedures with their own variables — nested, and free to call themselves.
- structured data
- Arrays and records: the program can hold collections, not just single numbers.
- the if-statement
- Conditional branching existed before the hardware it was designed for could run the code.
101First contact — hello world. 201 — 3 lessons on mechanisms you meet after the factorial specimen: the sharp edges practitioners actually use.
201 — going deeper
The 201 assumes you have read the 101 and the specimen. Each lesson is one mechanism — what it is for, how it looks in code, and the trap or payoff that makes Plankalkül distinctive at scale.
the conditional as control
Planalkül carried an if-statement and a while-style loop, so the language could express choice rather than only straight-line sequence.
why it never ran
The plans sat in drawers because the machines of 1945 could not store them. The first execution, in 2000, was a reconstruction from Zuse’s own paper.
The specimen — factorial
Zuse planned programs for a machine that no longer existed: assignment, subprograms and structured data — designed on paper in 1945, first executed only in 2000.
| Zuse's plan notation, 1945
V0[i] + V1[i] => R1
R1 => V2[i]reconstructed — notation of the era, simplified
Run it today
Nothing installs — that is the point. The first full Plankalkül program ran in 2000, reconstructed from Zuse’s paper. Rojas et al.’s implementation report is the tour.
Where it is now
Nowhere — and that is its story. Plankalkül defined assignment, subprograms and structured data before any stored-program computer existed in Germany; the plans sat in drawers until the 1970s, and the first faithful interpreter ran in 2000, fifty-five years late.