UNAUDITED CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Accumulated Deficit
Beginning balance (shares) at Apr. 30, 2018		11,003,228	(269,685)
Beginning balance at Apr. 30, 2018	$ 3	$ 11	$ (1,252)	$ 72,070	$ (70,826)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	75			75
Issuance of common stock for services (in shares)		4,762
Issuance of common stock on exercise of stock options (in shares)		20,000
Issuance of common stock on exercise of stock options	42			42
Net income (loss)	483				483
Ending balance (shares) at Jul. 31, 2018		11,027,990	(269,685)
Ending balance at Jul. 31, 2018	603	$ 11	$ (1,252)	72,187	(70,343)
Beginning balance (shares) at Apr. 30, 2018		11,003,228	(269,685)
Beginning balance at Apr. 30, 2018	3	$ 11	$ (1,252)	72,070	(70,826)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	381
Ending balance (shares) at Jan. 31, 2019		11,612,700	0
Ending balance at Jan. 31, 2019	2,323	$ 12	$ 0	72,756	(70,445)
Beginning balance (shares) at Jul. 31, 2018		11,027,990	(269,685)
Beginning balance at Jul. 31, 2018	603	$ 11	$ (1,252)	72,187	(70,343)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	88			88
Issuance of common stock on exercise of stock options (in shares)		446,815	269,685
Issuance of common stock on exercise of stock options	1,034		$ 1,252	(218)
Net income (loss)	267				267
Ending balance (shares) at Oct. 31, 2018		11,474,805	0
Ending balance at Oct. 31, 2018	1,992	$ 11	$ 0	72,057	(70,076)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	335			335
Issuance of common stock on exercise of stock options (in shares)		137,895
Issuance of common stock on exercise of stock options	365	$ 1		364
Net income (loss)	(369)				(369)
Ending balance (shares) at Jan. 31, 2019		11,612,700	0
Ending balance at Jan. 31, 2019	2,323	$ 12	$ 0	72,756	(70,445)
Beginning balance (shares) at Apr. 30, 2019		11,619,538	0
Beginning balance at Apr. 30, 2019	2,238	$ 12	$ 0	72,924	(70,698)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	131			131
Net income (loss)	(641)				(641)
Ending balance (shares) at Jul. 31, 2019		11,619,538	0
Ending balance at Jul. 31, 2019	1,728	$ 12	$ 0	73,055	(71,339)
Beginning balance (shares) at Apr. 30, 2019		11,619,538	0
Beginning balance at Apr. 30, 2019	2,238	$ 12	$ 0	72,924	(70,698)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	72
Ending balance (shares) at Jan. 31, 2020		11,823,274	0
Ending balance at Jan. 31, 2020	3,177	$ 12	$ 0	73,790	(70,625)
Beginning balance (shares) at Jul. 31, 2019		11,619,538	0
Beginning balance at Jul. 31, 2019	1,728	$ 12	$ 0	73,055	(71,339)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	77			77
Issuance of common stock on exercise of stock options (in shares)		625
Issuance of common stock on exercise of stock options	2			2
Net income (loss)	307				307
Ending balance (shares) at Oct. 31, 2019		11,620,163	0
Ending balance at Oct. 31, 2019	2,114	$ 12	$ 0	73,134	(71,032)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	229			229
Issuance of common stock on exercise of stock options (in shares)		203,111
Issuance of common stock on exercise of stock options	427			427
Net income (loss)	407				407
Ending balance (shares) at Jan. 31, 2020		11,823,274	0
Ending balance at Jan. 31, 2020	$ 3,177	$ 12	$ 0	$ 73,790	$ (70,625)