Casio personal-I (H-802)

Sometimes you're rewarded for looking around in second hand shops. Today, I found this Casio personal-I calculator in mint condition!

Not bad for the princely sum of £2.00, yes two whole pounds. Since I like a bit of retro, I had to own it, although I'll probably use it. It will look great on my desk at work.

As you can see here: was boxed (the box is in near perfect condition) and has the original instructions and batteries as well. I won't use the batteries, they're pretty old. The actual calculator was still in the protective plastic bag inside the box. It's in such perfect condition I don't think it has ever been switched on.

Of course, the buttons make that nice clicky noise that you only get from electronics of this era. I found more information about this model here.

Brunsviga 18RK

I’ve bought a Brunsviga 18RK mechanical calculating machine, since it is a piece of computing history.  Here it is:


It is awesome and I can report that everything seems to work.  It can’t do negative numbers, so I have enjoyed doing things like entering 100 and then subtracting 150  to get a result of 9999999999950. That’s called underflowing the accumulator, and a bell rings when you do it.

In its honour, I have also written this C program:

#include <stdio.h>
int main(int argc, char *argv[])
  unsigned char test='A';
 return 0;

…which underflows an unsigned char, subtracting 66 from 65 to get a result of 255.  For the sake of completeness I’m printing ACSII code 7 at the same time, so that a bell also sounds.  I’m sorry.