Comment by kazinator

Applesoft Basic, the principal "firmware" of the Apple II, was a derivative of Microsoft Basic.

"Apple reportedly obtained an eight-year license for Applesoft BASIC from Microsoft for a flat fee of $21,000, renewing it in 1985 through an arrangement that gave Microsoft the rights and source code for Apple's Macintosh version of BASIC." [http://en.wikipedia.org/wiki/Applesoft_BASIC]

Accessories for the Apple II is just an afterthought, really; kind of like Microsoft keyboards and mice for a Windows PC. :)