Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets
Cash	$ 12,534	$ 8,764
Investment securities, available-for-sale, at fair value	1,226	1,228
Accounts receivable, net
Trade - billed (less allowance for doubtful accounts of approximately $400), including contract retentions	10,922	9,798
Trade - unbilled	801	742
Inventories, net
Raw materials	713	643
Finished goods	1,634	1,551
Prepaid expenses and other assets	528	615
Total current assets	28,358	23,341
Property and equipment, net	18,528	18,602
Deferred buy-back lease asset, net	4,027	4,237
Other assets	295	319
Total assets	51,208	46,499
Current liabilities
Accounts payable - trade	2,567	1,866
Accrued expenses and other liabilities	664	875
Deferred revenue	2,091	1,774
Accrued compensation	1,387	1,318
Accrued income taxes	1,429	470
Deferred buy-back lease obligation	1,203	1,203
Operating lease liabilities	86	85
Current portion of PPP loan	750	0
Current maturities of notes payable	646	740
Customer deposits	853	569
Total current liabilities	11,676	8,900
Deferred revenue	804	600
Deferred buy-back lease obligation	3,489	3,790
Operating lease liabilities	189	211
Notes payable - less current maturities	4,094	4,196
PPP loan - less current portion	1,942	2,692
Deferred tax liability	2,457	2,461
Total liabilities	24,651	22,850
Stockholders' equity
Preferred stock, $.01 par value; authorized 1,000,000 shares, none issued and outstanding	0	0
Common stock, $.01 par value; authorized 8,000,000 shares; 5,279,411 and 5,279,411 issued and 5,202,158 and 5,202,158 outstanding, respectively	52	52
Additional paid-in capital	6,446	6,405
Treasury stock, at cost, 40,920 shares	(102)	(102)
Retained earnings	20,161	17,294
Total stockholders' equity	26,557	23,649
Total liabilities and stockholders' equity	$ 51,208	$ 46,499