[derleth]

There was an IE for UNIX back in the 1990s, which meant Solaris and HP-UX. The last version was IE5.

http://en.wikipedia.org/wiki/Internet_Explorer_for_UNIX

And before that, MicroSoft was best known for its BASIC implementation that wound up on a whole range of eight-bit microcomputers.

https://en.wikipedia.org/wiki/Microsoft_BASIC

The versions for 6502-based micros shared a codebase:

http://www.pagetable.com/?p=46

And, in some versions, they had an easter egg hidden in the constants used to implement SIN:

http://www.pagetable.com/?p=43