COMMERCIAL Digital Arithmetic Circuits 1,658

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Part	Manufacturer	Logic IC Type	Temperature Grade	Terminal Form	No. of Terminals	Package Code	Package Shape	Package Body Material	Surface Mount	No. of Functions	Technology	No. of Bits	Packing Method	Nominal Supply Voltage / Vsup (V)	Power Supplies (V)	Load Capacitance (CL)	Package Style (Meter)	Package Equivalence Code	Propagation Delay (tpd)	Maximum I (ol)	Sub-Category	Terminal Pitch	Maximum Operating Temperature	Output Characteristics	Terminal Finish	Terminal Position	JESD-30 Code	Moisture Sensitivity Level (MSL)	Maximum Supply Voltage (Vsup)	Maximum Seated Height	Width	Qualification	Output Polarity	Minimum Supply Voltage (Vsup)	Maximum Power Supply Current (ICC)	Additional Features	JESD-609 Code	Maximum Time At Peak Reflow Temperature (s)	Peak Reflow Temperature (C)	Length	Family
SN74AS882NT	Texas Instruments	LOOK-AHEAD CARRY GENERATOR	COMMERCIAL	THROUGH-HOLE	24	DIP	RECTANGULAR	PLASTIC/EPOXY	NO		TTL						IN-LINE	DIP24,.3			Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T24					Not Qualified
SN74ALS632BFN	Texas Instruments	ERROR DETECTION AND CORRECTION CIRCUIT	COMMERCIAL	J BEND	68	QCCJ	SQUARE	PLASTIC/EPOXY	YES	1	TTL	32		5		50 pF	CHIP CARRIER	LDCC68,1.0SQ	37 ns		Arithmetic Circuits	1.27 mm	70 Cel	3-STATE		QUAD	S-PQCC-J68		5.5 V	4.57 mm	24.2316 mm	Not Qualified		4.5 V	250 mA	BUILT IN DIAGNOSTICS; BYTE CONTROL		NOT SPECIFIED	NOT SPECIFIED	24.2316 mm	ALS
SN74AS881NT	Texas Instruments	ARITHMETIC LOGIC UNIT	COMMERCIAL	THROUGH-HOLE	24	DIP	RECTANGULAR	PLASTIC/EPOXY	NO		TTL						IN-LINE	DIP24,.3			Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T24					Not Qualified
SN74LS261J-00	Texas Instruments	MULTIPLIER	COMMERCIAL	THROUGH-HOLE	16	DIP	RECTANGULAR	CERAMIC, GLASS-SEALED	NO	1	TTL	4		5		15 pF	IN-LINE		37 ns			2.54 mm	70 Cel			DUAL	R-GDIP-T16		5.25 V	5.08 mm	7.62 mm	Not Qualified		4.75 V	40 mA	2'S COMPLEMENT RECODE MULTIPLIER				19.56 mm	LS
SN74S381N3	Texas Instruments	ARITHMETIC LOGIC UNIT	COMMERCIAL	THROUGH-HOLE	20	DIP	RECTANGULAR	PLASTIC/EPOXY	NO		TTL			5	5		IN-LINE	DIP20,.3			Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T20
SN74LS385N1	Texas Instruments	ADDER/SUBTRACTOR	COMMERCIAL	THROUGH-HOLE	20	DIP	RECTANGULAR	PLASTIC/EPOXY	NO		TTL						IN-LINE	DIP20,.3			Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T20					Not Qualified
SN74ALS518FN	Texas Instruments	IDENTITY COMPARATOR	COMMERCIAL	J BEND	20	QCCJ	SQUARE	PLASTIC/EPOXY	YES		TTL			5	5		CHIP CARRIER	LDCC20,.4SQ			Arithmetic Circuits	1.27 mm	70 Cel			QUAD	S-PQCC-J20					Not Qualified
SN74AS181NP1	Texas Instruments	ARITHMETIC LOGIC UNIT	COMMERCIAL	THROUGH-HOLE	24	DIP	RECTANGULAR	PLASTIC/EPOXY	NO		TTL						IN-LINE	DIP24,.6			Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T24					Not Qualified
SN74LS348FN3	Texas Instruments	ENCODER	COMMERCIAL	J BEND	20	QCCJ	SQUARE	PLASTIC/EPOXY	YES		TTL			5	5		CHIP CARRIER	LDCC20,.4SQ			Arithmetic Circuits	1.27 mm	70 Cel			QUAD	S-PQCC-J20
SN74LS280N3	Texas Instruments	PARITY GENERATOR/CHECKER	COMMERCIAL	THROUGH-HOLE	14	DIP	RECTANGULAR	PLASTIC/EPOXY	NO	1	TTL	9		5	5		IN-LINE	DIP14,.3	50 ns		Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T14		5.25 V	5.08 mm	7.62 mm	Not Qualified	COMPLEMENTARY	4.75 V		ODD/EVEN PARITY GENERATOR		NOT SPECIFIED	NOT SPECIFIED	19.305 mm	LS
SN74283NP1	Texas Instruments	ADDER/SUBTRACTOR	COMMERCIAL	THROUGH-HOLE	16	DIP	RECTANGULAR	PLASTIC/EPOXY	NO		TTL			5	5		IN-LINE	DIP16,.3			Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T16					Not Qualified
SN7480N	Texas Instruments	ADDER/SUBTRACTOR	COMMERCIAL	THROUGH-HOLE	14	DIP	RECTANGULAR	PLASTIC/EPOXY	NO	1	TTL	1		5		15 pF	IN-LINE	DIP14,.3	80 ns		Other Logic ICs	2.54 mm	70 Cel			DUAL	R-PDIP-T14		5.25 V	5.08 mm	7.62 mm	Not Qualified		4.75 V	35 mA	FULL ADDER; 4-IN GATED A/B OPERANDS; COMPLEMENTARY SUM OUTPUTS; PERMITS RIPPLE CARRY CASCADING		NOT SPECIFIED	NOT SPECIFIED	19.305 mm	TTL/H/L
SN74AS286NP3	Texas Instruments	PARITY GENERATOR/CHECKER	COMMERCIAL	THROUGH-HOLE	14	DIP	RECTANGULAR	PLASTIC/EPOXY	NO		TTL			5	5		IN-LINE	DIP14,.3			Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T14
SN74182J-00	Texas Instruments	LOOK-AHEAD CARRY GENERATOR	COMMERCIAL	THROUGH-HOLE	16	DIP	RECTANGULAR	CERAMIC, GLASS-SEALED	NO	1	TTL	4		5		15 pF	IN-LINE		22 ns			2.54 mm	70 Cel			DUAL	R-GDIP-T16		5.25 V	5.08 mm	7.62 mm	Not Qualified		4.75 V	72 mA	WITH HIGHER ORDER LOOKAHEAD				19.56 mm	TTL/H/L
SN74LS681JP4	Texas Instruments		COMMERCIAL	THROUGH-HOLE	20	DIP	RECTANGULAR	CERAMIC	NO		TTL						IN-LINE	DIP20,.3			Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-XDIP-T20
SN74LS382FN	Texas Instruments	ARITHMETIC LOGIC UNIT	COMMERCIAL	J BEND	20	QCCJ	SQUARE	PLASTIC/EPOXY	YES	1	TTL	4		5	5	15 pF	CHIP CARRIER	LDCC20,.4SQ	41 ns		Arithmetic Circuits	1.27 mm	70 Cel			QUAD	S-PQCC-J20		5.25 V	4.57 mm	8.9662 mm	Not Qualified		4.75 V	65 mA	CAPABLE OF 3 LOGIC & ARITHMETIC OPERATIONS; INTERNAL CARRY LOOKAHEAD		NOT SPECIFIED	NOT SPECIFIED	8.9662 mm	LS
SN74LS181N-10	Texas Instruments	ARITHMETIC LOGIC UNIT	COMMERCIAL	THROUGH-HOLE	24	DIP	RECTANGULAR	PLASTIC/EPOXY	NO	1	TTL	4		5		15 pF	IN-LINE		62 ns			2.54 mm	70 Cel			DUAL	R-PDIP-T24		5.25 V	5.08 mm	15.24 mm	Not Qualified		4.75 V	37 mA	CAPABLE OF 16 LOGIC & ARITHMETIC OPERATIONS				31.75 mm	LS
SN74LS381NP1	Texas Instruments	ARITHMETIC LOGIC UNIT	COMMERCIAL	THROUGH-HOLE	20	DIP	RECTANGULAR	PLASTIC/EPOXY	NO		TTL						IN-LINE	DIP20,.3			Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T20					Not Qualified
SN74AS264NP1	Texas Instruments	LOOK-AHEAD CARRY GENERATOR	COMMERCIAL	THROUGH-HOLE	16	DIP	RECTANGULAR	PLASTIC/EPOXY	NO		TTL						IN-LINE	DIP16,.3			Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T16					Not Qualified
SN74LS85NSRE4	Texas Instruments	MAGNITUDE COMPARATOR	COMMERCIAL	GULL WING	16	SOP	RECTANGULAR	PLASTIC/EPOXY	YES	1	TTL	4		5	5		SMALL OUTLINE	SOP16,.3	45 ns		Arithmetic Circuits	1.27 mm	70 Cel		NICKEL PALLADIUM GOLD	DUAL	R-PDSO-G16	1	5.25 V	2 mm	5.3 mm	Not Qualified	TRUE	4.75 V			e4	30	260	10.2 mm	LS
SN74LS685N3	Texas Instruments	MAGNITUDE COMPARATOR	COMMERCIAL	THROUGH-HOLE	20	DIP	RECTANGULAR	PLASTIC/EPOXY	NO		TTL			5	5		IN-LINE	DIP20,.3			Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T20
SN74S182N	Texas Instruments	LOOK-AHEAD CARRY GENERATOR	COMMERCIAL	THROUGH-HOLE	16	DIP	RECTANGULAR	PLASTIC/EPOXY	NO	1	TTL	4		5		15 pF	IN-LINE	DIP16,.3	10.5 ns		Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T16		5.25 V	5.08 mm	7.62 mm	Not Qualified	TRUE	4.75 V	109 mA	WITH HIGHER ORDER LOOKAHEAD		NOT SPECIFIED	NOT SPECIFIED	19.305 mm	S
SN74ALS528DWR	Texas Instruments	IDENTITY COMPARATOR	COMMERCIAL	GULL WING	16	SOP	RECTANGULAR	PLASTIC/EPOXY	YES	1	TTL	12		5		50 pF	SMALL OUTLINE		15 ns			1.27 mm	70 Cel			DUAL	R-PDSO-G16		5.5 V	2.65 mm	7.5 mm	Not Qualified	INVERTED	4.5 V	21 mA	FUSE PROGRAMMABLE INPUTS				12.8 mm	ALS
SN74F286D3	Texas Instruments	PARITY GENERATOR/CHECKER	COMMERCIAL	GULL WING	14	SOP	RECTANGULAR	PLASTIC/EPOXY	YES		TTL						SMALL OUTLINE	SOP14,.25			Arithmetic Circuits	1.27 mm	70 Cel			DUAL	R-PDSO-G14
SN74AS181ANW3	Texas Instruments	ARITHMETIC LOGIC UNIT	COMMERCIAL	THROUGH-HOLE	24	DIP	RECTANGULAR	PLASTIC/EPOXY	NO		TTL						IN-LINE	DIP24,.6			Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T24
SN74F286DR	Texas Instruments	PARITY GENERATOR/CHECKER	COMMERCIAL	GULL WING	14	SOP	RECTANGULAR	PLASTIC/EPOXY	YES	1	TTL	9		5			SMALL OUTLINE					1.27 mm	70 Cel			DUAL	R-PDSO-G14		5.5 V	1.75 mm	3.9 mm	Not Qualified	TRUE	4.5 V		EVEN PARITY GENERATOR				8.65 mm	F/FAST
SN74ALS521DWR	Texas Instruments	IDENTITY COMPARATOR	COMMERCIAL	GULL WING	20	SOP	RECTANGULAR	PLASTIC/EPOXY	YES	1	TTL	8	TR	5	5	50 pF	SMALL OUTLINE	SOP20,.4	20 ns	24 Amp	Arithmetic Circuit	1.27 mm	70 Cel	3-STATE	NICKEL PALLADIUM GOLD	DUAL	R-PDSO-G20	1	5.5 V	2.65 mm	7.5 mm	Not Qualified	INVERTED	4.5 V	19 mA	WITH PULL-UP RESISTORS ON Q INPUTS; CASCADABLE	e4	30	260	12.8 mm	ALS
SN74AS280N-10	Texas Instruments	PARITY GENERATOR/CHECKER	COMMERCIAL	THROUGH-HOLE	14	DIP	RECTANGULAR	PLASTIC/EPOXY	NO	1	TTL	9		5			IN-LINE					2.54 mm	70 Cel			DUAL	R-PDIP-T14		5.5 V	5.08 mm	7.62 mm	Not Qualified	COMPLEMENTARY	4.5 V		ODD/EVEN PARITY GENERATOR				19.305 mm	AS
SN74S280J-00	Texas Instruments	PARITY GENERATOR/CHECKER	COMMERCIAL	THROUGH-HOLE	14	DIP	RECTANGULAR	CERAMIC, GLASS-SEALED	NO	1	TTL	9		5		15 pF	IN-LINE		18 ns			2.54 mm	70 Cel			DUAL	R-GDIP-T14		5.25 V	5.08 mm	7.62 mm	Not Qualified	COMPLEMENTARY	4.75 V	105 mA	ODD/EVEN PARITY GENERATOR				19.56 mm	S
SN74ALS522J	Texas Instruments	IDENTITY COMPARATOR	COMMERCIAL	THROUGH-HOLE	20	DIP	RECTANGULAR	CERAMIC	NO		TTL			5	5		IN-LINE	DIP20,.3			Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-XDIP-T20					Not Qualified
SN74LS85D3	Texas Instruments	MAGNITUDE COMPARATOR	COMMERCIAL	GULL WING	16	SOP	RECTANGULAR	PLASTIC/EPOXY	YES		TTL			5	5		SMALL OUTLINE	SOP16,.25			Arithmetic Circuits	1.27 mm	70 Cel			DUAL	R-PDSO-G16
SN74181NP1	Texas Instruments	ARITHMETIC LOGIC UNIT	COMMERCIAL	THROUGH-HOLE	24	DIP	RECTANGULAR	PLASTIC/EPOXY	NO		TTL			5	5		IN-LINE	DIP24,.6			Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T24					Not Qualified
SN74ALS522N1	Texas Instruments	IDENTITY COMPARATOR	COMMERCIAL	THROUGH-HOLE	20	DIP	RECTANGULAR	PLASTIC/EPOXY	NO		TTL			5	5		IN-LINE	DIP20,.3			Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T20					Not Qualified
SN74ALS677FN	Texas Instruments	ADDRESS COMPARATOR	COMMERCIAL	J BEND	28	QCCJ	SQUARE	PLASTIC/EPOXY	YES		TTL						CHIP CARRIER	LDCC28,.5SQ			Arithmetic Circuits	1.27 mm	70 Cel			QUAD	S-PQCC-J28					Not Qualified
SN74LS283DRE4	Texas Instruments	ADDER/SUBTRACTOR	COMMERCIAL	GULL WING	16	SOP	RECTANGULAR	PLASTIC/EPOXY	YES	1	TTL	4		5	5	15 pF	SMALL OUTLINE	SOP16,.25	24 ns		Arithmetic Circuits	1.27 mm	70 Cel			DUAL	R-PDSO-G16		5.25 V	1.75 mm	3.9 mm	Not Qualified		4.75 V	39 mA	FULL ADDER; WITH INTERNAL CARRY LOOKAHEAD; PERMITS RIPPLE CARRY CASCADING		NOT SPECIFIED	NOT SPECIFIED	9.9 mm	LS
SN74ALS677AFN3	Texas Instruments	ADDRESS COMPARATOR	COMMERCIAL	J BEND	28	QCCJ	SQUARE	PLASTIC/EPOXY	YES		TTL						CHIP CARRIER	LDCC28,.5SQ			Arithmetic Circuits	1.27 mm	70 Cel			QUAD	S-PQCC-J28
SN74AS264DP3	Texas Instruments	LOOK-AHEAD CARRY GENERATOR	COMMERCIAL	GULL WING	16	SOP	RECTANGULAR	PLASTIC/EPOXY	YES		TTL						SMALL OUTLINE	SOP16,.25			Arithmetic Circuits	1.27 mm	70 Cel			DUAL	R-PDSO-G16
SN74ALS679FN-00	Texas Instruments	ADDRESS COMPARATOR	COMMERCIAL	J BEND	20	QCCJ	SQUARE	PLASTIC/EPOXY	YES	1	TTL	12		5		50 pF	CHIP CARRIER		30 ns			1.27 mm	70 Cel			QUAD	S-PQCC-J20		5.5 V	4.57 mm	8.9662 mm	Not Qualified	INVERTED	4.5 V	28 mA	WITH INHIBIT				8.9662 mm	ALS
SN74LS385FN	Texas Instruments	ADDER/SUBTRACTOR	COMMERCIAL	J BEND	20	QCCJ	SQUARE	PLASTIC/EPOXY	YES	4	TTL	1		5		15 pF	CHIP CARRIER	LDCC20,.4SQ			Arithmetic Circuits	1.27 mm	70 Cel			QUAD	S-PQCC-J20		5.25 V	4.57 mm	8.9662 mm	Not Qualified		4.75 V	75 mA	SERIAL ADDER/SUBTRACTOR		NOT SPECIFIED	NOT SPECIFIED	8.9662 mm	LS
SN74AS286DG4	Texas Instruments	PARITY GENERATOR/CHECKER	COMMERCIAL	GULL WING	14	SOP	RECTANGULAR	PLASTIC/EPOXY	YES	1	TTL	9		5	5	50 pF	SMALL OUTLINE	SOP14,.25	14 ns		Arithmetic Circuits	1.27 mm	70 Cel	3-STATE	NICKEL PALLADIUM GOLD	DUAL	R-PDSO-G14	1	5.5 V	1.75 mm	3.9 mm	Not Qualified	TRUE	4.5 V	43 mA	EVEN PARITY GENERATOR; ODD/EVEN PARITY CHECKER; WITH PARITY I/O AND ACTIVE LOW PARITY ERROR OUTPUT	e4	30	260	8.65 mm	AS
SN74LS280DR	Texas Instruments	PARITY GENERATOR/CHECKER	COMMERCIAL	GULL WING	14	SOP	RECTANGULAR	PLASTIC/EPOXY	YES	1	TTL	9		5	5	15 pF	SMALL OUTLINE	SOP14,.25	50 ns		Arithmetic Circuits	1.27 mm	70 Cel			DUAL	R-PDSO-G14		5.25 V	1.75 mm	3.9 mm	Not Qualified	COMPLEMENTARY	4.75 V	27 mA	ODD/EVEN PARITY GENERATOR		NOT SPECIFIED	NOT SPECIFIED	8.65 mm	LS
SN74AS181ANW	Texas Instruments	ARITHMETIC LOGIC UNIT	COMMERCIAL	THROUGH-HOLE	24	DIP	RECTANGULAR	PLASTIC/EPOXY	NO	1	TTL	4		5		15 pF	IN-LINE	DIP24,.6	21 ns		Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T24		5.5 V			Not Qualified		4.5 V	200 mA	CAPABLE OF 16 LOGIC & ARITHMETIC OPERATIONS; INTERNAL CARRY AND HIGHER ORDER LOOKAHEAD		NOT SPECIFIED	NOT SPECIFIED		AS
SN74ALS521NE4	Texas Instruments	IDENTITY COMPARATOR	COMMERCIAL	THROUGH-HOLE	20	DIP	RECTANGULAR	PLASTIC/EPOXY	NO	1	TTL	8		5	5	50 pF	IN-LINE	DIP20,.3	20 ns		Arithmetic Circuits	2.54 mm	70 Cel	3-STATE	NICKEL PALLADIUM GOLD	DUAL	R-PDIP-T20		5.5 V	5.08 mm	7.62 mm	Not Qualified	INVERTED	4.5 V	19 mA	WITH PULL-UP RESISTORS ON Q INPUTS; CASCADABLE	e4			25.4 mm	ALS
SN74ALS527FN3	Texas Instruments	ADDRESS COMPARATOR	COMMERCIAL	J BEND	20	QCCJ	SQUARE	PLASTIC/EPOXY	YES		TTL						CHIP CARRIER	LDCC20,.4SQ			Arithmetic Circuits	1.27 mm	70 Cel			QUAD	S-PQCC-J20
SN74AS280NP1	Texas Instruments	PARITY GENERATOR/CHECKER	COMMERCIAL	THROUGH-HOLE	14	DIP	RECTANGULAR	PLASTIC/EPOXY	NO		TTL			5	5		IN-LINE	DIP14,.3			Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T14					Not Qualified
SN74LS637NP1	Texas Instruments	ERROR DETECTION AND CORRECTION CIRCUIT	COMMERCIAL	THROUGH-HOLE	20	DIP	RECTANGULAR	PLASTIC/EPOXY	NO		TTL						IN-LINE	DIP20,.3			Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T20					Not Qualified
SN74ALS634JD-00	Texas Instruments	ERROR DETECTION AND CORRECTION CIRCUIT	COMMERCIAL	THROUGH-HOLE	48	DIP	RECTANGULAR	CERAMIC, METAL-SEALED COFIRED	NO	1	TTL	32		5			IN-LINE		58 ns				70 Cel	3-STATE		DUAL	R-CDIP-T48		5.5 V			Not Qualified		4.5 V	250 mA	BUILT IN DIAGNOSTICS					ALS
SN74AS866NP1	Texas Instruments	MAGNITUDE COMPARATOR	COMMERCIAL	THROUGH-HOLE	28	DIP	RECTANGULAR	PLASTIC/EPOXY	NO		TTL						IN-LINE	DIP28,.6			Arithmetic Circuits	2.54 mm	70 Cel			DUAL	R-PDIP-T28					Not Qualified

Digital Arithmetic Circuits

Digital arithmetic circuits are electronic circuits designed to perform arithmetic operations on digital signals. These circuits are essential components of digital systems, such as microprocessors, digital signal processors, and programmable logic devices.

Digital arithmetic circuits can perform various arithmetic operations, including addition, subtraction, multiplication, division, and modulo arithmetic. These operations are performed using binary arithmetic, where numbers are represented using the binary number system (0s and 1s).

Adders are one of the most commonly used digital arithmetic circuits. They are used to perform binary addition, where two binary numbers are added to produce a sum. Adders can be designed using various techniques, including ripple carry adders, carry look-ahead adders, and carry select adders.

Subtractors are also commonly used digital arithmetic circuits. They are used to perform binary subtraction, where one binary number is subtracted from another to produce a difference. Subtractors can be designed using techniques, including ripple borrow subtractors, borrow look-ahead subtractors, and borrow select subtractors.

Multiplexers and demultiplexers are digital circuits that can be used for various arithmetic operations, such as multiplication and division. Multiplexers can be used to select one of several input signals based on a control signal, while demultiplexers can be used to distribute a single input signal to several outputs based on a control signal.

Digital arithmetic circuits can also be designed using programmable logic devices, such as field-programmable gate arrays (FPGAs) and complex programmable logic devices (CPLDs). These devices can be programmed to implement various arithmetic operations and can be reprogrammed to adapt to changing system requirements.