Look right at the top of the page: the E5 is Triscend's 8051-based "Configurable System on a Chip" (CSoC) - an 8051 core with programmable logic integrated onto a single chip.

http://www.triscend.com/products/IndexE5.html

You can find the full datasheet, the reference designs, app notes, etc, etc at

http://www.triscend.com/products/IndexTechLit.html

(Note that this includes stuff for their A7 - the ARM-based version)