A BSD kernel, a gui from Next and a object orientated version of C from before C++ !
Technology-wise Apple basically takes a steam train, wraps a Bang+Olufson case around it and makes it emit the scent of roses!
Nice toys, very well made, but cutting edge technology doesn't underpin Apple's success.
http://en.wikipedia.org/wiki/Berkeley_Software_Distribution
BSD is still used in Free/Open/Net/BSD; and Next's GUI was based on Display Postscript, which was easily tuned for PDF (PS and PDF are very similar languages)
What you will notice is that all of these choices were designed by very small teams, sometimes just 1 person was involved in the original design:
BSD - Bill Joy and a few others made the major design decisions
Next GUI - Keith Ohlfs, on top of DPS licensed from Adobe
Objective C - designed mainly by Brad Cox
You missed the Mach kernel, originally a small research project from CMU, Avie Tevanian worked on porting Mach to a multi-processor system in the early to mid 1980s.
In fact their technology is and always has been (when did Mac-0S get real multi-tasking?) rather conservative.
Precisely - it's the user experience that puts Apple out
ahead not cutting edge technology.
As soon as possible after Jobs' return.
He kept them because they work well.