STATEMENTS OF CASH FLOWS - USD ($)	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating Activities:
Net income (loss)	$ (576,000)	$ 907,000
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	1,101,000	851,000
Changes in allowance for doubtful accounts	41,000	(19,000)
Deferred income tax expense	0	119,000
Stock-based compensation expense	150,000	267,000
Gain on sale of property and equipment	(5,000)	(25,000)
Changes in operating assets and liabilities:
Accounts receivable	338,000	457,000
Inventories	(184,000)	55,000
Income tax receivable	(324,000)	277,000
Prepaid expenses and other	(266,000)	118,000
Accounts payable	(1,271,000)	(379,000)
Accrued liabilities	(1,098,000)	498,000
Income tax payable	(184,000)	159,000
Excess tax benefit from stock-based awards	0	(4,000)
Deferred revenue	(128,000)	456,000
Net cash provided by (used in) operating activities	(2,406,000)	3,737,000
Investing Activities:
Purchases of property and equipment	(524,000)	(137,000)
Purchases of investments	0	(4,513,000)
Proceeds from sale or maturity of investments	6,071,000	4,308,000
Proceeds received from sale of property and equipment	5,000	25,000
Net cash provided by (used in) investing activities	5,552,000	(317,000)
Financing Activities:
Proceeds from issuance of common stock, net	44,000	48,000
Excess tax benefit from stock-based awards	0	4,000
Repurchase of common stock, net	(301,000)	(1,614,000)
Net cash used in financing activities	(257,000)	(1,562,000)
Increase in cash and cash equivalents	2,889,000	1,858,000
Cash and cash equivalents at beginning of period	8,523,000	7,237,000
Cash and cash equivalents at end of period	11,412,000	9,095,000
Supplemental disclosures for cash flow information:
Cash paid during the period for income taxes	$ 238,000	$ 243,000