Summary of Share Based Compensation Expense Related to Share Based Payment Awards and Employee Stock Purchases (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 26, 2014	Sep. 27, 2013	Sep. 28, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation expense related to employee stock options, restricted stock awards and employee stock purchase plan	$ 1,659	$ 1,462	$ 1,604
Cost of sales
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation expense related to employee stock options, restricted stock awards and employee stock purchase plan	114	84	102
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation expense related to employee stock options, restricted stock awards and employee stock purchase plan	58	91	144
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation expense related to employee stock options, restricted stock awards and employee stock purchase plan	213	251	203
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation expense related to employee stock options, restricted stock awards and employee stock purchase plan	1,274	1,036	1,155
Operating expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation expense related to employee stock options, restricted stock awards and employee stock purchase plan	$ 1,545	$ 1,378	$ 1,502