Reply to post: ABC80

0ops. 1,OOO-plus parking fine refunds ordered after drivers typed 'O' instead of '0'

Torben Mogensen

ABC80

In the 1980s there was a Swedish-made home computer called ABC80. On this computer, the pixel patterns for O and 0 were EXACTLY the same. Since O and 0 are close on a keyboard, this could give hard-to-find errors when programming in BASIC. Is this a variable called "O" or the number 0? It didn't help that the designers had the bright idea that distinguishing integer constants from floating point constants, you added a "%" at the end of integer constants (similar to how integer variables were suffixed in most BASICs at the time). So O% and 0% were both valid. Variable names could only be a single letter or a single letter followed by a single digit (and suffixed with % or $ to indicate integer or string variables). All in all, this was not hugely user friendly. The follow-up ABC800 added a dot in the centre of zero, but the BASIC was otherwise the same.

I was the happy owner of a BBC Micro, but I was briefly hired by a company to port some school software to ABC80. The way it operated on strings used huge amounts of memory, so I had to add a small machine-code routine to make in-place updates (insert char, delete char, replace char) in strings to keep it from running out of memory.

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