Note 1 - Summary of Significant Accounting Policies (Details Textual)		3 Months Ended			6 Months Ended	9 Months Ended
	Oct. 01, 2020 USD ($)	Sep. 25, 2021 USD ($) shares	Sep. 25, 2021 USD ($)	Sep. 26, 2020 USD ($) shares	Jun. 24, 2021	Sep. 25, 2021 USD ($) shares	Sep. 26, 2020 USD ($) shares	Dec. 26, 2020 USD ($)
Accounts Receivable, Allowance for Credit Loss, Ending Balance		$ 400,000	$ 400,000			$ 400,000		$ 100,000
Capitalized Computer Software, Gross		13,300,000	$ 13,300,000			13,300,000		13,500,000
Capitalized Computer Software, Amortization		400,000		$ 300,000		$ 1,157,000	$ 830,000
Number of Operating Segments						3
Number of Reportable Segments			1		2
Goodwill and Intangible Asset Impairment, Total	$ 0
Amortization of Debt Issuance Costs		100,000		300,000		$ 500,000	900,000
Foreign Currency Transaction Gain (Loss), Realized		$ (28,000)		$ (1,500,000)		$ (300,000)	$ (2,500,000)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) | shares		239,000		109,000		160,000	151,000
Revenue, Remaining Performance Obligation, Amount		$ 7,800,000	$ 7,800,000			$ 7,800,000
Deferred Revenue, Total		20,100,000	20,100,000			20,100,000		17,100,000
Deferred Profit		11,295,000	11,295,000			11,295,000		8,671,000	[1]
Deferred Profit Long-term		6,200,000	6,200,000			6,200,000		6,700,000
Accumulated Other Comprehensive Income (Loss), Net of Tax, Total		$ (19,413,000)	$ (19,413,000)			$ (19,413,000)		$ (4,326,000)	[1]
Computer Software, Intangible Asset [Member]
Finite-Lived Intangible Asset, Useful Life (Year)						7 years
Minimum [Member]
Standard Product Warranty Term (Month)						12 months
Maximum [Member]
Standard Product Warranty Term (Month)						36 months
Building [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)						30 years
Building [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)						40 years
Building Improvements [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)						5 years
Building Improvements [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)						15 years
Machinery, Equipment and Software [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)						3 years
Machinery, Equipment and Software [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)						10 years

[1] Derived from December 26, 2020 audited financial statements