Statements of Stockholders' Equity (Unaudited) - USD ($)	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Total
Balance (in shares) at Dec. 28, 2019	13,427,492
Balance at Dec. 28, 2019	$ 134,275	$ 36,094,201	$ (30,380,433)	$ (517,053)	$ 5,330,990
Share-based compensation expense	$ 0	83,063	0	0	83,063
Issuance of common stock (in shares)	0
Issuance of common stock	$ 0	0	0	0	$ 0
Employee option exercises (in shares)					0
Net income			900,885	0	$ 900,885
Balance (in shares) at Jun. 27, 2020	13,427,492
Balance at Jun. 27, 2020	$ 134,275	36,177,264	(29,479,548)	(517,053)	6,314,938
Balance (in shares) at Mar. 28, 2020	13,427,492
Balance at Mar. 28, 2020	$ 134,275	36,159,874	(29,778,779)	(517,053)	5,998,317
Share-based compensation expense	$ 0	17,390	0	0	17,390
Issuance of common stock (in shares)	0
Issuance of common stock	$ 0	0	0	0	$ 0
Employee option exercises (in shares)					0
Net income			299,231	0	$ 299,231
Balance (in shares) at Jun. 27, 2020	13,427,492
Balance at Jun. 27, 2020	$ 134,275	36,177,264	(29,479,548)	(517,053)	$ 6,314,938
Balance (in shares) at Dec. 26, 2020	13,746,242				13,746,242
Balance at Dec. 26, 2020	$ 137,462	36,688,894	(29,472,369)	(996,323)	$ 6,357,664
Share-based compensation expense	$ 0	119,535	0	0	119,535
Issuance of common stock (in shares)	479,900
Issuance of common stock	$ 4,793	3,132,599	0	0	$ 3,137,392
Employee option exercises (in shares)	629,900				629,900
Employee option exercises	$ 6,299	1,234,630	0	(1,229,700)	$ 11,229
Treasury shares retired (in shares)	(554,660)
Treasury shares retired	$ (5,547)	(2,218,706)	0	2,224,253
Net income			270,101	0	$ 270,101
Balance (in shares) at Jun. 26, 2021	14,300,771				14,300,771
Balance at Jun. 26, 2021	$ 143,007	38,956,952	(29,202,268)	(1,770)	$ 9,895,921
Balance (in shares) at Mar. 27, 2021	14,360,042
Balance at Mar. 27, 2021	$ 143,600	37,925,674	(29,441,466)	(2,201,509)	6,426,299
Share-based compensation expense	$ 0	92,113	0	0	92,113
Issuance of common stock (in shares)	479,289
Issuance of common stock	$ 4,793	3,132,599	0	0	$ 3,137,392
Employee option exercises (in shares)	16,100				16,100
Employee option exercises	$ 161	25,272	0	(24,514)	$ 919
Treasury shares retired (in shares)	(554,660)
Treasury shares retired	$ (5,547)	(2,218,706)	0	2,224,253	0
Net income	$ 0	0	239,198	0	$ 239,198
Balance (in shares) at Jun. 26, 2021	14,300,771				14,300,771
Balance at Jun. 26, 2021	$ 143,007	$ 38,956,952	$ (29,202,268)	$ (1,770)	$ 9,895,921