If you've ever been curious about the first ever computer spreadsheet, you can download VisiCalc itself and give it a try. Dan Bricklin, inventor of the spreadsheet, received permission from Lotus who now own the copyright for VisiCalc to allow him to offer it for free on his website. The actual executable weighs in at a paltry 27 kilobytes, and would run on a PC from 1981 - in fact it is virtually identical to the one that shipped for DOS 1.0. The only difference is that the copy protection has been removed.

VisiCalc is a piece of personal computing history, and is arguably the "killer application" that ushered in the era of personal computers.

We were lucky enough to have Dan post a comment recently at The Unofficial Microsoft Weblog.