This is one of my favorites. Some relevant link:
Wikipedia has a good write up (http://en.wikipedia.org/wiki/CDC_6600), but don't miss out on this classic written by Thornton himself:
http://computer-refuge.org/bitsavers/pdf/cdc/6x00/books/DesignOfAComputer_CDC6600.pdf
Tommy
Biting the hand that feeds IT
