Verilog simulators are software packages that emulate the Verilog

Verilog

In the semiconductor and electronic design industry, Verilog is a hardware description language used to model electronic systems. Verilog HDL, not to be confused with VHDL , is most commonly used in the design, verification, and implementation of digital logic chips at the register-transfer level...

 hardware description language

Hardware description language

In electronics, a hardware description language or HDL is any language from a class of computer languages, specification languages, or modeling languages for formal description and design of electronic circuits, and most-commonly, digital logic...

. Verilog simulation software has come a long way since its early origin as a single proprietary product offered by one company. Today, Verilog simulators are available from many vendors, at all price points. For desktop/personal use, Aldec, Mentor, LogicSim, SynaptiCAD, and others offer <$5000 USD tool-suites for the Windows 2000/XP platform. The suites bundle the simulator engine with a complete development environment: text editor, waveform viewer, and RTL-level browser. Additionally, limited-functionality editions of the Aldec and ModelSim simulator are downloadable free of charge, from their respective OEM partners (Actel, Altera, Lattice Semiconductor, Xilinx, etc.) For those desiring open-source software, there is Icarus Verilog

Icarus Verilog

Icarus Verilog is an implementation of the Verilog hardware description language. It supports the 1995, 2001 and 2005 versions of the standard, portions of SystemVerilog, and some extensions....

, among others.

Beyond the desktop level, enterprise-level simulators offer faster simulation runtime, more robust support for mixed-language (VHDL and Verilog) simulation, and most importantly, are validated for timing-accurate (SDF-annotated) gate-level simulation. The last point is critical for the ASIC

ASIC

ASIC may refer to:* Application-specific integrated circuit, an integrated circuit developed for a particular use, as opposed to a customised general-purpose device.* ASIC programming language, a dialect of BASIC...

 tapeout process, when a design-database is released to manufacturing. (Semiconductor foundries stipulate the usage of tools chosen from an approved list, in order for the customer's design to receive signoff status. Although the customer is not required to perform any signoff checking, the tremendous cost of a wafer order has generally ensured thorough design-validation on the part of the customer.) The three major signoff-grade simulators include Cadence Incisive Enterprise Simulator, Mentor ModelSim/SE, and Synopsys VCS. Pricing is not published publicly, but all three vendors charge $25,000-$100,000 USD per seat, 1-year time-based license.

FPGA vendors do not require expensive enterprise simulators for their design flow. In fact, most vendors include an OEM version of a third-party HDL simulator in their design suite. The bundled simulator is taken from an entry-level or low-capacity edition, and bundled with the FPGA vendor's device libraries. For designs targeting high-capacity FPGA, a standalone simulator is recommended, as the OEM-version may lack the capacity or speed to effectively handle large designs.

Below is a list of simulators that implement the Verilog hardware description language.

Commercial Simulators

List of Verilog Simulators in Alphabetical Order by Name

Simulator Name	Author/Company	Languages	Description
Active-HDL/Riviera	Aldec	VHDL-2002, V2001, SV2005	A simulator with complete design environment aimed at FPGA-applications. Aldec licenses Active-HDL to FPGA-vendors, and the underlying engine can be found in the design-suites of those vendors. While ActiveHDL is a low-cost product, Aldec also offers a more expensive, higher-performance simulator called "Riviera."
	CVC	Tachyon Design Automation	V2001, V2005	CVC is a Verilog HDL compiled simulator. CVC has the ability to simulate in either interpreted or compiled mode.
	Incisive Enterprise Simulator ('big 3')	Cadence Design Systems Cadence Design Systems Cadence Design Systems, Inc is an electronic design automation software and engineering services company, founded in 1988 by the merger of SDA Systems and ECAD, Inc...	VHDL-2002, V2001, SV2005	Cadence initially acquired Gateway Design, thereby acquiring Verilog-XL. In response to competition from faster simulators, Cadence developed its own compiled-language simulator, NC-Verilog. The modern version of the NCsim family, called Incisive Enterprise Simulator, includes Verilog, VHDL, and SystemVerilog support. It also provides support for the e verification language, and a fast SystemC simulation kernel.
	ISE Simulator	Xilinx	VHDL-93, V2001	Xilinx's simulator comes bundled with the ISE Design Suite. ISE Simulator (ISim) provides support for mixed-mode language simulation including, but not limited to, simulation of designs targeted for Xilinx's FPGAs and CPLDs.
	ModelSim ('big 3')	Mentor Graphics Mentor Graphics Mentor Graphics, Inc is a US-based multinational corporation dealing in electronic design automation for electrical engineering and electronics, as of 2004, ranked third in the EDA industry it helped create...	VHDL-2002, V2001, SV2005	The original Modeltech (VHDL) simulator was the first mixed-language simulator capable of simulating VHDL and Verilog design entities together. However, as the Verilog component of ModelSim is neither the fastest nor most fully featured simulator on the market, competition from Synopsys and Cadence, led to a continual decrease in ModelSim popularity.
	PureSpeed	Frontline	V1995	The simulator had a cycle-based counterpart called 'pure cycle'. FrontLine was sold to Avant!, which was later acquired by Synopsys. Synopsys discontinued Purespeed in favor of its well-established VCS simulator.
	Quartus II Simulator	Altera	VHDL-1993, V2001, SV2005	Altera's simulator bundled with the Quartus II design software. Supports Verilog, VHDL and AHDL.
	SILOS	Simucad Design Automation	V2001	As one of the low-cost interpreted Verilog simulators, Silos III enjoyed great popularity in the 1990s. Simucad's most current version, Silos-X, is sold as part of a tool-suite.
	SMASH	Dolphin Integration	V1995, V2001, VHDL-1993	SMASH is a mixed-signal, multi-language simulator for IC or PCB designs. It uses SPICE SPICE SPICE is a general-purpose, open source analog electronic circuit simulator.It is a powerful program that is used in integrated circuit and board-level design to check the integrity of circuit designs and to predict circuit behavior.- Introduction :Unlike board-level designs composed of discrete...  syntax for analog descriptions, Verilog-HDL and VHDL for digital, Verilog-A/AMS, VHDL-AMS and ABCD (a combination of SPICE and C) for analog behavioral, and C for DSP algorithms.
	Speedsim	Cadence Design Systems Cadence Design Systems Cadence Design Systems, Inc is an electronic design automation software and engineering services company, founded in 1988 by the merger of SDA Systems and ECAD, Inc...	V1995	Cycle based simulator originally developed at DEC. The DEC developers spun off to form Quickturn Design Systems. Quickturn was later acquired by Cadence, who discontinued the product in 2005. Speedsim featured an innovative slotted bit-slice architecture that supported simulation of up to 32 tests in parallel.
	Super-FinSim	Fintronic	V2001	This simulator is available on multi-platform, claiming IEEE 1364-2001 compliance.
	VCS	Synopsys	VHDL-2002, V2001, SV2005	Originally developed by John Sanguinetti, Peter Eichenberger and Michael McNamara under the startup company Chronologic Simulation, VCS (Verilog Compiled code Simulator) was purchased by Synopsys, where development continued. Due to a strategic decision to support SystemVerilog (instead of SystemC), and the acquisition of Superlog (the forerunner to SystemVerilog), Synopsys/VCS was the first SystemVerilog simulator in the market.
	Verilogger Extreme, Verilogger Pro	SynaptiCAD	V2001,V1995	Verilogger Pro is a low-cost interpreted simulator based on Elliot Mednick's VeriWell code base. Verilogger Extreme is a newer, compiled-code simulator that is Verilog-2001 compliant and much faster than Pro.
	Verilog-XL	Cadence	V1995	The original Verilog simulator, Gateway Design's Verilog-XL was the first (and only, for a time) Verilog simulator to be qualified for ASIC (validation) sign-off. After its acquisition by Cadence Design Systems, Verilog-XL changed very little over the years, retaining an interpreted language engine, and freezing language-support at Verilog-1995. Cadence recommends Incisive Enterprise Simulator for new design projects, as XL no longer receives active development. Nevertheless, XL continues to find use in companies with large codebases of legacy Verilog. Many early Verilog codebases will only simulate properly in Verilog-XL, due to variation in language implementation of other simulators.
	Veritak	Sugawara Systems	V2001	It is low-cost and Windows-based only. It boasts a built-in waveform viewer and fast execution.
	Z01X	WinterLogic	V2001,SV2005	Developed as a fault simulator but can also be used as a logic simulator.

Some commercial simulators (such as ModelSim) are available in student, or evaluation/demo editions. These editions generally have many features disabled, arbitrary limits on simulation design size, but are offered free of charge.

Open-source Simulators

List of Verilog Simulators in Alphabetical Order

Simulator Name	Author/Company	Supported Languages	Description
GPL Cver	Pragmatic C Software	V1995, minimal V2001	This is a GPL open-source simulator. It is a pure simulator. This simulator is not fully IEEE 1364-2001 compliant. It does not support generate and constant functions.
	Icarus Verilog Icarus Verilog Icarus Verilog is an implementation of the Verilog hardware description language. It supports the 1995, 2001 and 2005 versions of the standard, portions of SystemVerilog, and some extensions....	Stephen Williams	V1995, V2001, limited V2005/V2009	This simulator is not fully IEEE 1364-2001 compliant. It does not support constant functions.
	Verilator Verilator Verilator is a free and open source software tool which converts Verilog to a cycle accurate behavioral model in C++ or SystemC. It is restricted to modeling the synthesizable subset of Verilog and the generated models are cycle accurate, 2-state, with synthesis semantics...	Veripool	Synthesizable V2001, synthesizable V2005, minimal synthesizable SV2009	This is a very high speed open-source simulator that compiles synthesizable Verilog to C++/SystemC.
	VeriWell	Elliot Mednick	V1995	This simulator used to be commercial, but has recently become GPL open-source. Compliance with 1364 is not well documented. It is not fully compliant with IEEE 1364-1995.
	LIFTING	A. Bosio, G. Di Natale (LIRMM)	V1995	LIFTING (LIRMM Fault Simulator) is an open-source simulator able to perform both logic and fault simulation for single/multiple stuck-at faults and single event upset (SEU) on digital circuits described in Verilog.
	ParC	Kevin Cameron	Functional superset	C++ extensions inspired by Verilog, VHDL, CSP Communicating sequential processes In computer science, Communicating Sequential Processes is a formal language for describing patterns of interaction in concurrent systems. It is a member of the family of mathematical theories of concurrency known as process algebras, or process calculi...  and the shortcomings of SystemVerilog. Adds HDL threading model and event driven programming to C++.

Key

Tag	Description
V1995	IEEE 1364-1995 Verilog Verilog In the semiconductor and electronic design industry, Verilog is a hardware description language used to model electronic systems. Verilog HDL, not to be confused with VHDL , is most commonly used in the design, verification, and implementation of digital logic chips at the register-transfer level...
V2001	IEEE 1364-2001 Verilog Verilog In the semiconductor and electronic design industry, Verilog is a hardware description language used to model electronic systems. Verilog HDL, not to be confused with VHDL , is most commonly used in the design, verification, and implementation of digital logic chips at the register-transfer level...
V2005	IEEE 1364-2005 Verilog Verilog In the semiconductor and electronic design industry, Verilog is a hardware description language used to model electronic systems. Verilog HDL, not to be confused with VHDL , is most commonly used in the design, verification, and implementation of digital logic chips at the register-transfer level...
SV2005	IEEE 1800-2005 SystemVerilog SystemVerilog In the semiconductor and electronic design industry, SystemVerilog is a combined Hardware Description Language and Hardware Verification Language based on extensions to Verilog.-History:...
SV2009	IEEE 1800-2009 SystemVerilog SystemVerilog In the semiconductor and electronic design industry, SystemVerilog is a combined Hardware Description Language and Hardware Verification Language based on extensions to Verilog.-History:...
VHDL-1987	IEEE 1076 IEEE 1076 The IEEE Standard 1076 defines the VHSIC Hardware Description Language or VHDL. It was originally developed under contract F33615-83-C-1003 from the United States Air Force awarded in 1983 to a team with Intermetrics, Inc. as language experts and prime contractor, with Texas Instruments as chip... -1987 VHDL
VHDL-1993	IEEE 1076 IEEE 1076 The IEEE Standard 1076 defines the VHSIC Hardware Description Language or VHDL. It was originally developed under contract F33615-83-C-1003 from the United States Air Force awarded in 1983 to a team with Intermetrics, Inc. as language experts and prime contractor, with Texas Instruments as chip... -1993 VHDL
VHDL-2002	IEEE 1076 IEEE 1076 The IEEE Standard 1076 defines the VHSIC Hardware Description Language or VHDL. It was originally developed under contract F33615-83-C-1003 from the United States Air Force awarded in 1983 to a team with Intermetrics, Inc. as language experts and prime contractor, with Texas Instruments as chip... -2002 VHDL
VHDL-2008	IEEE 1076 IEEE 1076 The IEEE Standard 1076 defines the VHSIC Hardware Description Language or VHDL. It was originally developed under contract F33615-83-C-1003 from the United States Air Force awarded in 1983 to a team with Intermetrics, Inc. as language experts and prime contractor, with Texas Instruments as chip... -2008 VHDL