[dewitt]

Neat project, unexpected title. I thought the PDP-11 (and the PDP line in general) was designed as an explicit alternative to "Big Iron", i.e. a minicomputer.

http://www.wolfgang-houben.de/faqpdp11.htm

[bitwize]

Well, they became the new big iron once powerful microprocessor-based machines became commonplace.

(DEC did make a microprocessor version of the PDP-11 called the DEC Professional, but it failed to catch on.)