Annual report pursuant to Section 13 and 15(d)

Note 8 - Sale of Common Stock (Details Textual)

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Note 8 - Sale of Common Stock (Details Textual) - USD ($)
 12 Months Ended
Mar. 11, 2020
Nov. 08, 2019
Nov. 07, 2019
Mar. 28, 2018
Mar. 28, 2020
Mar. 30, 2019
Stock Issued During Period, Shares, New Issues (in shares) 146,668 699,333        
Shares Issued, Price Per Share (in dollars per share) $ 3.75 $ 3.75        
Proceeds from Issuance of Common Stock $ 510,000 $ 2,100,000     $ 2,564,000 $ 1,192,000
Stock Issued During Period, Value, New Issues $ 550,004       $ 2,564,000  
Series E Preferred Stock [Member]            
Stock Issued During Period, Shares, New Issues (in shares)       42,800 0 56,200
Shares Issued, Price Per Share (in dollars per share)       $ 25   $ 25
Preferred Stock, Shares Outstanding, Ending Balance (in shares)         9,200 98,400
Preferred Stock, Liquidation Preference, Value         $ 345,000 $ 3,690,000
Stock Issued During Period, Value, New Issues           $ 1,193,000
Conversion of Series E Preferred Stock into Common Stock [Member]            
Conversion of Stock, Shares Issued (in shares)   896,636 896,636      
Conversion of Stock, Shares Converted (in shares)   88,600 88,600      
Underwriter Warrants [Member]            
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)   20,980        
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)   $ 4.50        
Warrants and Rights Outstanding, Term (Year)   5 years