Before there was Mac OS 7, before there was MultiFinder, there was
Switcher. Developed independently by Andy Hertzfeld, it was later sold
commercially as Macintosh Switcher Construction Kit.

DL #1 contains the following versions of Switcher: 2.0, 3.5, 4.0, 4.3,
4.4E, 5.0E.

DL #2 (Switcher.dsk.sit) is a stuffed .dsk image containing a System
folder (2.0, I think) and all the versions I was able to scrabble
together: 4.0, 4.4, 5.0 and 5.0.1. The file dates are all inauthentic,
ugh, except for 5.0.1 which came from the physical disk mentioned
below.

DL #3 (Switcher Construction Kit.image.sit) is a DC 4.2 image of the
physical Switcher disk I found in my archives (version 5.0.1, from
1986). It is not pure (what are those word setting files doing there?)
but it is an unaltered image of the disk exactly as I found it.

DL #4 contains a compilation that includes all of the above versions
plus a number of others. The versions included are 2.0, 2.6, 3.5, 4.0,
4.3, 4.4E, 4.4F, 4.9, 5.0E, 5.0b4, 5.01B, 5.0.1, 5.1a13, 5.1

Compatibility
Architecture: 68k