Resurrected Entertainment


September 17, 2007

VisiCALC on the AtariI was exposed to this piece of software at about the same time I was learning how to send graphical data to our printer. I didn’t really appreciate the complexity of this software until much later. My father was the one who was the real expert, but I also fired it up to help with my homework and to calculate some values I needed for a few of the games I was writing. It was the first time I had ever seen a spread sheet program, even though it appeared on the Apple II a couple of years earlier. Financially, the program was a boon for Apple and almost single-handedly lead to the mass adoption of the system. Financially, I’m not sure how it fared on the Atari since it took the company about a year to port it to other systems, but it’s common to see systems for sale on eBay which are being sold with a few games, miscellaneous pieces of software, and VisiCALC.This spread sheet software introduced me to a world where software can be used for something other than playing games. Although, let’s face it, they’re not as much fun or practical these days. I think I absorbed that idea pretty well for a boy who hadn’t quite entered his teenage years. I started to think about how I could write programs for my father which would help him with his financial chores. I don’t think I produced anything terribly useful, but I did write a few small calculator programs which could do a few interesting calculations involving trigonometry and simple algebra. I hadn’t yet discovered decimal encoding techniques like Binary Coded Decimal (BCD), but I eventually learned that Atari used BCD routines in its library implementation which BASIC used extensively. VisiCALC was able to handle floating point values efficiently because it was written in assembly language and the 6502 processor has floating point instructions available. The programmers used these instructions directly instead of using Atari’s library, which had a very positive impact on performance.

For more information on the development of VisiCALC, there are a couple of sources on the Internet available including one from the creators themselves.

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