Income Taxes - Deferred Tax Effects (Detail) (USD $) In Thousands, unless otherwise specified	Jul. 31, 2013	Jul. 31, 2012
Deferred tax effects of the Company's principal temporary differences
Allowance for doubtful receivables	$ 105	$ 177
Inventories	227	858
Basis difference in property and equipment	(12)	(5)
Accrued warranty costs	87	50
Accrued expenses and other	123	115
Deferred revenue	0	(42)
Net operating loss carry-forwards	10,668	9,663
Valuation allowance	(11,198)	(10,816)
Total deferred tax asset	$ 0	$ 0