Acorn User articles

Acorn User is a publication dedicated to Acorn 's family of microcomputers: initially the Atom, then the famous BBC microcomputer, followed by the powerful Acorn Archimedes, then the RISC-PC (and now ...?).

I bought my first BBC micro in 1983, and was fascinated by the spectacular fractal effects that I could generate with very short programs. And programs that short are ideal for publishing in popular computing magazines!


Susan Stepney. Prime Candidates. Acorn User , June 1991.

Finding Mersenne primes , using the Lucas-Lehmer test .

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I state in the article that " The biggest [Mersenne prime] known to date [1991] is M 216091 ". Ones a lot larger than that are known nowadays !


Susan Stepney. Life on the Line. Acorn User , November 1988.

Conway's well-known 'Game of Life' is a two-dimensional cellular automata. Here I explore the just-as-complex one-dimensional cellular automata, the advantage being that you can display multiple generations simultaneously.

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I state in the article that " It's probably the case that some of the 1D rules also give computationally irreducible automata, but this has yet to be proved. " It has now been proved for rule 110 (by Cook in 2004) ... and, in a wonderful coincidence, the listing for this program was printed on p.110 !


Susan Stepney. Snowflakes and other monsters. Acorn User , March 1984.

How to draw 'pathological' fractal curves, by defining the 'generator' shape, and letting the computer iterate. One such 'monster curve' is the Koch snowflake, which has infinite length, but encloses a finite area.

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Susan Stepney. Incredible fractals. Acorn User , October 1983.

One of the earliest articles on fractals in a popular computing magazine. Factoid: I had no access to a printer at the time, except one on an IBM 3081 mainframe. So I had to recode the algorithms in Fortran to produce the pictures!

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