Note 1 - Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 27, 2021

Notes Tables

Schedule of Inventory, Current [Table Text Block]

	March 27,		December 26,
	2021		2020
Raw materials and purchased parts	$	90,890	$	83,755
Work in process		54,247		44,315
Finished goods		15,734		14,430
Total inventories	$	160,871	$	142,500

Property, Plant and Equipment [Table Text Block]

	March 27,			December 26,
	2021			2020
Land and land improvements	$	7,934		$	8,141
Buildings and building improvements		40,247			41,153
Machinery and equipment		64,599			65,342
		112,780			114,636
Less accumulated depreciation and amortization		(47,004	)		(47,720	)
Property, plant and equipment, net	$	65,776		$	66,916

Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

	Three Months Ended
	March 27,			March 28,
	2021			2020
Cost of sales	$	262		$	212
Research and development		781			833
Selling, general and administrative		2,480			2,566
Total share-based compensation		3,523			3,611
Income tax benefit		(234	)		(172	)
Total share-based compensation, net	$	3,289		$	3,439

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

	Three Months Ended
	March 27,		March 28,
	2021		2020
Weighted average common shares		43,756		41,502
Effect of dilutive securities		1,726		-
		45,482		41,502

Disaggregation of Revenue [Table Text Block]

	Three Months Ended
Disaggregated Net Sales	March 27, 2021		March 28, 2020
Systems:
Semiconductor Test & Inspection	$	138,159	$	70,539
PCB Test		8,620		6,840
Non-systems:
Semiconductor Test & Inspection		74,247		57,474
PCB Test		4,462		4,068
Total net sales	$	225,488	$	138,921

	Three Months Ended
Disaggregated Net Sales	March 27, 2021		March 28, 2020
China	$	54,265	$	30,811
Philippines		33,754		10,022
Taiwan		32,196		13,881
Malaysia		23,259		15,174
United States		20,059		19,078
Rest of the World		61,955		49,955
Total net sales	$	225,488	$	138,921

Schedules of Concentration of Risk, by Risk Factor [Table Text Block]

	Three Months Ended
	March 27,		March 28,
	2021		2020
Semiconductor Test & Inspection
Customers individually accounting for more than 10% of net sales		*		two
Percentage of net sales		*		26%
PCB Test
Customers individually accounting for more than 10% of net sales		*		*
Percentage of net sales		*		*