MultiFinder is an extension for the Apple Macintosh's classic Mac OS, introduced on August 11, 1987[1] and included with System Software 5.
[citation needed] As the successive Macintosh hardware models were released with much more RAM being the key feature, new programming techniques were developed as workarounds to allow users to run concurrent applications.
To allow some degree of freedom and to deliver the GUI's promise of interface consistency, the original Macintosh includes Desk Accessories, such as a calculator, that can be run concurrently.
Andy Hertzfeld, one of Apple's original Macintosh software architects, wrote Switcher after seeing John Markoff use a terminate-and-stay-resident program on an IBM PC in October 1984.
Though awkward, this approach does fit well with the existing system's memory management scheme, and applications need no special programming to work with Switcher.
[5] This early work on Switcher led to the development of MultiFinder by Apple system software engineers Erich Ringewald and Phil Goldman.
Microsoft saw Switcher as especially benefiting the company's highly memory-optimized Macintosh applications[4] so the utility was shipped with Excel.
Showing up sometime in late 1985, after the introduction of Switcher, and being credited as being made by Jwa van der Vuurst with a copyright by Aubrac Systems, it makes over 200 direct calls to undocumented addresses in the Macintosh ROMs.
[11] Its file manager is unusual due to its lack of a scrollbar, instead requiring to hold and drag the window background like a modern map app.
One of its most interesting features is the first known implementation of wallpapers on the Macintosh, allowing users to replace the default grey background with MacPaint or ThunderScan images.
[17] Later in 1987, System 6 engineer Erich Ringewald's desire to solve these architectural problems altogether would bring him to defiantly cofound and lead the Pink project as the intended future of a new MacOS,[18] and then become chief software architect at Be Inc. to design BeOS in 1990.
Two utilities, CPU Doubler and Peek-A-Boo, did implement a form of priority based task scheduling in the classic Mac OS, though they were unable to solve its other issues, like the lack of protected memory.