March 12, 1985: The First Mac Switcher

When the first Mac was being developed the designers saw no need to address the issue of running multiple programs. The oversight was understandable; the programmers were working hard enough just to develop the system and a single program to run in 64K, which the Mac was originally intended to ship with.

Things, however, change. RAM prices dropped and memory demands became simply too great for 64K to be close to adequate. Hence the original Mac shipped with 128K instead of the originally planned 64K.

While 128K still wasn't truly adequate (remember Steve Jobs demoed the first Mac using a Mac Plus prototype) it did leave a little bit of wiggle room, wiggle room that was exploited by Mac genius Andy Hertzfeld. Hertzfeld wrote a program called Switcher, using very clever tricks, that allowed the Mac to run programs simultaneously. The first Mac "switcher" with functionality that wouldn't become standard until the release of system 6 appeared this month in 1985.