computer science

PS-algol

PS-algol is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand PS-algol rather than just read about it. In short: PS-algol is an orthogonally persistent programming language. PS-algol was an extension of the language S-algol implemented by the University of St Andrews and the University of Edinburgh, Scotland.

Key takeaways

PS-algol belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect PS-algol to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of PS-algol from memory before moving on to harder problems.

Reference excerpt

PS-algol is an orthogonally persistent programming language. PS-algol was an extension of the language S-algol implemented by the University of St Andrews and the University of Edinburgh, Scotland. S-algol was designed by Ron Morrison and extended by Pete Bailey, Fred Brown, Paul Cockshott, Ken Chisholm, and Al Dearle. These extensions were additional standard functions that provide a persistent heap that survives termination of PS-algol programs. PS-algol was the world's first fully implemented persistent programming language, and had many users both in academia and, notably, in International Computers Limited (ICL) research labs.

History PS-algol was conceived by chance, when Ron Morrison was on sabbatical at the University of Edinburgh and met Malcolm Atkinson. Atkinson had been experimenting with persistent programming languages and was struggling to find a coherent model for a persistent Pascal variant. Morrison, whose interest in general-purpose programming had led to the development of S-algol, a general purpose teaching language, realised that S-algol's type system would more easily allow adding orthogonal persistence.

Worked examples

Example 1 — a first encounter with PS-algol

Start with the simplest possible case. Write down what PS-algol claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to PS-algol before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about PS-algol ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of PS-algol

In research: PS-algol appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses PS-algol in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: PS-algol is common in secondary-school and first-year university syllabi. It links to neighbouring topics Algol programming language family, History of computing in the United Kingdom, Programming language topic stubs, so understanding it makes those chapters shorter.
In everyday life: Look for PS-algol outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study PS-algol in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what PS-algol means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain PS-algol out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is PS-algol in simple terms?

PS-algol is an orthogonally persistent programming language. PS-algol was an extension of the language S-algol implemented by the University of St Andrews and the University of Edinburgh, Scotland.

Why does PS-algol matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study PS-algol?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on PS-algol.