Subotnick was one of my first introductions to experimental music, in a composition class in 1977, taught by Merill Ellis at the University of North Texas. Recently I met Morton briefly in NYC, where he was giving a performance of a new work. He's quite an old man now, but full of creative energy and immense good humor.
I first learned about Mr. Subotnick in a class about the development of electronic music, among other titans of the 20th century avant-garde music. Many of these composers will never earn the widespread appreciation they are due for their accomplishments, but they left an indelible mark on music production, and serve as inspiration for a surprisingly wide breadth of artists.
Just going by Wayback Machine, it looks like the site is essentially unchanged since at least 2007. It was first indexed in 1998, however I didn't go back as far as that.
Be careful touching it in general. A lot of people said the rotary sequencer was enlightening, but that's just because they never found the door of perception hidden inside the unit...