Inventories (Details) (USD $) In Thousands, unless otherwise specified	Jul. 31, 2012	Jul. 31, 2011
Inventories
Raw materials and purchased components	$ 1,151	$ 1,612
Work in process	894	291
Finished goods	5,355	5,797
Total	7,400	7,700
Inventory obsolescence reserve	(2,139)	(2,184)
Total inventories	$ 5,261	$ 5,516