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The Hamburg
VHDL archive
Welcome to the Hamburg VHDL archive! We intend to provide a collection of free, i.e. public-domain or shareware, VHDL documentation, models, and tools.

This service is provided and maintained by group TAMS, Faculty of Informatics, University of Hamburg.

Feedback We are always looking for additional documents, models, tools and Internet links to improve this server. All contributions, hints, and corrections are welcome. Please contact Norman Hendrich or Andreas Mäder.

Please consider to contribute some of your own models and tools to the VHDL-community in turn for any information downloaded from one of the free VHDL servers.

Internet VHDL
and Resources
The following list represents our (subjective) selection of VHDL and EDA/CAD related WWW and ftp-servers. Most public-domain or free VHDL stuff can be found there. For more addresses, try one of the WWW search-engines.
VIUF The WWW-server of the VHDL International (VI) Users' Forum (VIUF).
EDA.ORG The EDA Industry Working Groups WWW-server, with links to the VHDL working groups, VHDL resources, IEEE standards, International Conferences ...
The working groups provide additional information on specialized topics and drafts. They are accessible via the EDA.org Wiki:
P1076 VHDL Analysis and Standardization Group
P1076.1 VHDL-AMS
P1647 Functional Verfification Language
P1734 Electronic Design Intellectual Property (IP) Quality
P1735 IP Encryption and Use Right Management
P1778 Esterel v7 Language (for system design: mixed HW+SW)
P1800 System Verilog
VerilogAMS VerilogAMS
P1801 Low Power Design
FMF The Free Model Foundry (FMF) provides free VITAL compliant VHDL models. Besides hundreds of standard components and memories, their model list also includes many current commercial parts (e.g. Flash memories, dual-port memories, microcontrollers).
comp.lang.vhdl The only VHDL related Usenet newsgroup. Unfortunately, with sub-average signal-to-noise ratio on some topics.
RASSP The excellent VHDL server from the RASSP project.
thor.ece.uc.edu VHDL and CAD/EDA server of the University of California.
cs.utwente.nl VHDL and CAD/EDA server at the university of Twente.
erm1.u-strasbg.fr Server of the ERM/PHASE team at the E.N.S.P.S. (University of Strasbourg), with a search engine for their collection of free VHDL models.
www.fp.fmv.se A server in Sweden.
OpenCores From the OpenCores missions statement: 'OPENCORES.ORG is a repository of open source, free IP synthesizable blocks and supplemental prototype boards. Most of our cores are currently under development but some are already available.'
P1076.1 Working group: Analog and Mixed-Signal Extensions to VHDL
The first address for VHDL-AMS.
VHDL-AMS.de Some VHDL-AMS references, server under construction...
Southampton VHDL-AMS Validation Suite, Models and Examples
VHDL Forum A new discussion forum for VHDL (in German). However, as the forum is only a few days old, there is very little traffic so far.

VHDL FAQ The four parts FAQ collection of the comp.lang.vhdl newsgroup, which is reposted about monthly. The most recent version can be obtained from the EDA.ORG server. The FAQ is also available in PDF format for printing.

The links below are to local copies of the FAQ on our server, which are not updated on a regular basis: Part 1/pdf, Part 2/pdf, Part 3/pdf, Part 4/pdf

Documentation This section presents VHDL documentation of all sort - textbooks, tutorials, tool descriptions, etc.:
VHDL cookbook The yet classical introduction into VHDL and hardware design by Peter J. Ashenden. It presents the complete description of a non-pipelined 32-bit microprocessor. The link is to our local copy of the PDF version of the book. See ftp.cs.adelaide.edu.au/pub/VHLD-Cookbook/ for the cookbook homepage.
VHDL Kompakt An introduction to VHDL in German with small design examples and lots of syntax diagrams (what statement is allowed where) by Andreas Mäder (558Ki PDF file).

The previous version: "VHDL Kurzbeschreibung" (238K compressed Postscript file).

HDL Übersicht
A short, introductional presentation for the students on VHDL (HDLs) - 475 PDF file, in German. The material serves as preparation for lab-sessions or practical courses and is for 3 to 4 hours of lecture (including practical demonstration).
mit VHDL
An introduction to VHDL 1987/1993 simulation and synthesis in German, originally published as a book by Franzis Verlag. Now available in PDF format for free (personal use).
Amontec VHDL memo Browsable syntax (VHDL'87) with additional context information and small examples.
VHDL: an introduction An elementary introduction to VHDL, written as his master's thesis by Francis Bruno, in chapters: Also by Francis Bruno, a VHDL tutorial: VHDL Representations of some hardware architectures, a basic computer and an assembler:
VHDL verification course Introduction to VHDL simulation together with some utility VHDL source code. Covers topics from basic testbenches to file I/O, signal monitors, checking of timing-constraints, etc. Also gives hints to scripting, file organization, and test strategy.
VHDL-Online A Hypertext-based-VHDL-Learning System from the University of Karlsruhe, consisting of an Online-Manual and a VHDL-Syntax Reference from the authors of the book: Schaltungsdesign mit VHDL.
Style guides A selection of VHDL style and modelling guides:
VHDL modelling guide The ESA (European Space Agency) guidelines for VHDL modelling. Presents the modelling style required for ESA design qualification with lots of useful tricks and conventions (65K compressed Postscript).
The VHDL Standard The ESA VHDL status report. An overview of activities, organizations and European tool efforts (127K compressed Postscript).
VHDL modelling guide US Navy 'Standard Hardware and Reliability Program' (SHARP) Technology Independent Representation of Electronic Products (TIREP) report. Available as 541K compressed Unix .tar.gz archive or in individual chapters:
VHDL-AMS Information related to the IEEE 1076.1 Standard
VHDL-AMS Tutorial Analog and Mixed-Signal Modeling Using the VHDL-AMS Language
Excellent tutorial, from the DAC'99 (673K PDF, 199 pages)
EDA-tools Howto's and recipes for commercial VHDL simulators and VLSI design tools

All vendors of Electonic Design Automation (EDA) tools provide extensive documentation on "efficient HDL coding" (for VHDL, Verilog, SystemC etc.) and samples. So refer to your synthesis and simulation tool docs for best practice material.

online-doc Our online-documentation about the Synopsys DC tools, Cadence NC-Simulator and Cadence DFII (schematic- and layout-editor) in combination with AMS or Atmel CMOS design kits (in German).
A complete list of tools installed at our institite is here - for questions on these tools contact Andreas Mäder.

Papers A collection of several VHDL related technical reports and conference papers.

This section is obviously not complete. Please submit your papers!

Recursive and repetitive VHDL modelling Peter J. Ashenden: Recursive and repetitive VHDL modelling. Discusses recursive and iterative structure descriptions for both VHDL-87 and VHDL-93 (117K compressed Postscript).
The corresponding models are available here (53K ASCII).
BABEL machine W. Hans, J.J. Ruz, F. Sáenz, S. Winkler: A VHDL Specification of a Shared Memory Parallel Machine for Babel (60 pages, 128K compressed Postscript).
Femto-VHDL John Van Tassel: Femto-VHDL: The semantics of a subset of VHDL and its embedding in the HOL theorem-prover. (479K compressed Postscript tar, or individual chapters) PhD dissertation, University of Cambridge
VHDL quality checking The VLSI-group of the Universidad politecnica de Madrid has some papers about VHDL design flow and automatically checking the quality of VHDL code.
Verification Some papers about verification and model checking using VHDL tools:

Draft Standard Proposals During the standardization process, some of the working groups provide draft material and standard proposals for public discussion, see links under EDA.ORG.
Notice, that these drafts are not the official standards, therefore refer to

Models and Packages Our collection of public-domain VHDL models and packages. If you cannot find a model here, please make sure to check the other VHDL servers listed on top of this page.
Packages Standardized packages, as part of the IEEE Standards, are not free and have to be bought from the above address. The following packages are either draft standards and proposals from the working groups or free (vendor specific) packages. Please see and respect the copyright notice inside the files.

Before download, please check your tool- or vendor-specific documentation, since most tools have the standard packages already included. Often they use specialized versions, which are optimized with respect to the internal algorithms.

SoftCores A private website with four synthesizable microprocessor cores: PPX16 (PIC16C55, PIC16F84), T80 (Z80), T51 (8051), and AX8 (90S1200, 90S2313). The site also offers some utilities, including a converter from Intel Hex and Motorola S-Record files to VHDL ROM descriptions, and a tool to read and write synchronous serial (I2S) data to files.
HC11 core Both behavioural and RTL source code for the HC11 microcontroller core from Green Mountain Computing Systems. Not surprinsingly, makefiles and project files are optimized for their own VHDL simulator.
8051 MCU A new 8051 MCU IP core under LGPL license, co-developed by Oregano Systems and the University of Wien. The model is synthesizable, fully synchronous, and includes timer and UART interfaces.
mc8051 Both behavioural and structural (synthesizable) models of the 8051 µController, with memory blocks but without peripherial devices. The model comes with testbench and several .hex files.
i8051 Another synthesizable model of the 8051 µController core (without interrupt handling). Includes ROM and RAM blocks but no peripheral devices. The model comes with several test programs.
PIC 16C5x A structural model of the PIC16C5x microcontroller under the GNU public license from Ernesto Romani (romani@ascu.unian.it). The model has been synthesized to a Xilinx 4005 FPGA and comes together with a tool to convert assembler code to a VHDL ROM model.

compressed tar archive (267K, structural VHDL model, assembly packer, some documentation)

Check www.microchip.com for datasheets, documentation, and (free) tools for the PIC series of microcontrollers.

A VHDL simulation model of the ERC32, a radiation tolerant SPARC processor for space applications, complete with documentation and makefiles for the Synopsys and Model Tech simulators.

All models are fully functional with parametrisable timing. The source code and data sheets for the models are provided for free (GNU license) via the ERC32 home page: ERC32 WWW-Server.

The processor consists of integer unit, floating-point unit and memory controller. IU and FPU are compatible with the Cypress 76C01 and 76C02 Sparc V7 processors.

The LEON processor is a synthesizable implementation of the SPARC-V8 architecture, distributed under the LGPL license. The processor includes a five-stage integer pipeline and an AMBA-style bus with several peripherial blocks. The LEON source code is also an interesting example of using VHDL data types and generics for model configuration. The processor has been sythesized to several target libraries, as well as Altera and Xilinx FPGAs.
DLX Both behavioral and RT-level model of Hennessy and Patterson's generic 32bit RISC-processor architecture (without instruction pipeline, however).
compressed tar archive (37K, VHDL description and two simple programs).
directory with the uncompressed files.
SuperScalar DLX SuperScalar DLX:
A PPC603-style superscalar mixed behaviour/RTL model of the DLX processor from the TU Darmstadt, Germany:
  • superscalar, pipelined implementation of DLX (but without floating-point)
  • 4 separate functional untis: branch-resolve, arithmetic-logical, multiply-divide, load-store
  • 5-entry reorder buffer, up to 5 active instructions
  • 4-entry branch-target-buffer
  • precise exceptions
  • small 64-entry I-cache and D-cache
The link above contains documentation, all VHDL models, and some test programs in ZIP format. The VHDL code itself is nicely commented and very readable.
GL85 GL85: This circuit is an op-code compatible clone of the i8085 8-bit microprocessor:
6502 A behavioural (but synthesizable) model of the 6502 microprocessor from the Free-IP site.
i80386 A simple (and incomplete) behavioral model of the Intel 80386 microprocessor (58K ASCII).
m68000 A simple (and incomplete) behavioral model of the Motorola 68000 microprocessor (36K ASCII).
AMD 2901 AMD 2901 bit slice(Unix .tar.gz)
AMD 2910 bit slice(Unix .tar.gz)
A simulation model for the 24Cxx series of I2C EEPROMs from M. Neumann used for verification of a I2C-master.
and Testbench
Another I2C EEPROM simulation model with timing checks and file dump/load mechanism, together with a procedural testbench simulating an I2C-master.
SRAM, full timing Our generic SRAM model with full timing, by A. Klindworth. The model uses generic parameters for timing and size, timing checks, startup initialization from file, memory dump to file, etc.
SRAM, no timing A simple model of a 64Kx8 SRAM without timing, but with startup initialization from a file.
DRAM A DRAM model by Shannon Hill (posted to comp.lang.vhdl)
EPROM, no timing A simple 64Kx8 EPROM model without timing checks, but with an Intel-HEX file parser for initialization.
Vendor memory models Today, several memory vendors offer VHDL simulation models for their products. For example, Micron Technology offers downloadable (but licensed) simulation models for several memory products, including double data rate SDRAM and SGRAM.
Misc. & Cores Note that some of the files listed in this section are demo versions or behavioural versions of otherwise commercial products. They are listed here among fully free software because they implement important and useful cores - e.g. PCI or USB controllers.
Jane neural network processor VHDL and Verilog sources for a programmable neural network processor by Suresh Kumar. The download consists of a ~2MByte archive file which contains the source files and documentation. See the "Guide/About.html" file in the archive file for an overview.
USB core While the (synthesizable) USB controller core itself is a commercial product, Trenz electronic provides the behavioural model and testbenches under GNU licence for free (see the "free downloads" link.) They also offer a clone of the MCS51 microcontroller.
Free-DES A synthesizable core for DES encryption from the Free-IP site.
CRC LFSR A cyclic-redundancy-check feedback shift-register, by Russ DeHoedt (posted to comp.lang.vhdl)
MCNC circuits The standard CAD-benchmark circuits of the MCNC (ftp.mcnc.org).
FPGA course A collection of circuits and testbenches for our recent FPGA lab. course, which uses Altera FPGAs. For example, you will find another SRAM model and a component to convert ASCII-strings into RS232 (8N1) format. Irdafuse is a circuit to protect an IrDA tranceiver from accidental overload during testing of student's designs.
FFT A synthesizable model of a FFT generator together with a full description (420KB PDF). From the author's submission mail: The design of the processor was taken from an IEEE workshop report. The report detailed a 256-point FFT I have limited mine to an 8-point FFT for easier debugging, which obviously cannot be used as such, since its accuracy would be poor. Neverthless all the features of the processor are present and upgrading it to a 256 point processor is easy.
Bidirectional delay
The model of a bidirectional connection, simulating line reflections for passive (off-switched) drivers from M. Neumann.

VHDL-Tools Our collection of public-domain VHDL tools. If you cannot find a tool here, please make sure to check the other VHDL servers listed on top of this page.
IDEs Several new projects (as well as commercial products) are working on toolchains integrating project management, editing, simulation and synthesis tasks within one development environment. Especially Eclipse based tools (plugins) have to be mentioned here.

Currently these tools are either good editors or simulators or waveform viewers, but this is work in progress and functionality is growing rapidly...

Signs The Signs project is working at an Eclipse plugin for (V)HDL hardware development. Currently the toolchain contains an editor, a parser (generating internal representations), a schematic output (!) with cross-referencing capabilities and a simulation engine along with waveform output.
Source code is also available at SourceForge.
SimplifIDE SimplifIDE is a (commercial) development environment focused on HDL entry and code parsing. A basic free version contains standard editing features for VHDL.
Sigasi HDT Another (commercial) development tool is Sigasi HDT. It contains an VHDL parser and compiler that runs transparently in the background. This enables advanced design assistance such as intelligent navigation, instant error reporting, intelligent code completion, quickfixes and automated refactoring.
A free public beta of the IDE is available.
IVI A graphical front-end for various simulators. IVI allows the user to control simulation and view signal waveforms as the data is produced by the simulation.
Grammar and Parsers
VHDL-93 Hyperlinked BNF of the VHDL-93 BNF grammar. Or get the ASCII version.
VHDL grammar VHDL lex/yacc grammar (20K compressed ASCII).
VAUL VHDL Analyzer and Utility Library (VAUL) parser home page at the University of Dortmund. VAUL is written in C++ and needs flex/bison.
our local but outdated copy (University of Hamburg) (520K tar.gz).
VHDL-AMS and VHDL-93 parser See under "Selected Projects" for several Parser and Design Browser written in SWI-Prolog
  • VHDL-AMS Parser / Pretty Printer System
  • VHDL-AMS Design Browser (IEEE 1076.1)
  • VHDL-93 Parser
  • VHDL-93 Design Browser
VHDL-AMS parser Another VHDL-AMS parser, implemented in java.
VHDL lex/yacc parser VHDL parser vhdl-lexyacc.1.4 by Thomas Dettmers (19K compressed tar).
VHDL parser in Java VHDLParser and VHDLTree: a GNU licensed VHDL parser and parse-tree viewer written in Java.
VHDL parser VHDL parser vhdl-rexlalr.1.2 from the University of Twente, based on the GMD Compiler Tool Box CCTB (35K compressed tar).

Parser frontend vhdlfront.1.1 (100K compressed tar).

VHDL Object Model Parser A parser written in the REFINE system, Ohio Board of Regents and the University of Cincinnati (36K compressed tar), individual files.
vhdl2vl A GPL'ed converter from VHDL to Verilog
vhdl-2-c A prototype VHDL-2-C compiler (for sequential statements).
Simulators Many vendors offer trial versions of commercial products, which are restricted in design complexity, simulation speed and/or license expiration. Most FPGA vendors also have VHDL simulators restricted to their device families.
VHDL Simili An integrated development environment from Symphony EDA with a fast VHDL compiler and simulator, a waveform viewer and a GUI with project management, editing and debugging capabilities. The compiler/simulator can be used as batch tools. VHDL Simili development is currently available for FREE (intended for small designs, as the performance will be disgraded on large designs) or you can request a demo/trial license for the full version.
BlueHDL Restricted but free demo version of a VHDL/Verilog/SystemC simulator for Windows and Linux from from Blue Pacific Computing, Inc. The free Student Version is limited to 50k bytes of source code (about 2500 lines), 1000 total signals, 100 displayed signals and 4k events per signal.
Simulators free projects (GPL or similiar licenses)
GHDL A compiling VHDL simulator using GCC technology, supporting VHDL-87 and VHDL-93 standards. A waveform viewer GTKWave (see below) can be connected and there is also a port to IVI (Eclipse integration).
One of the best choices for free VHDL simulation (under Linux)!
Alliance The Alliance CAD system (Universite de Paris).
Inspire A free VHDL simulator from Korea.
FreeHDL project A project to develop a free, open source, GPL'ed VHDL simulator for Linux! The goal of the project is to develop a VHDL-93 compliant simulator with graphical waveform viewer, source level debugger, and with commercial quality.

While some of the parser, simulator and tool code is already available, the project is still looking for new members and supporters!

Waveform Viewer
Frontend tools

GTKWave Powerful waveform viewer for various output formats (VCD/EVCD/LXT/Synopsys), based on GTK+ toolkit.
IVI A graphical front-end for various simulators. IVI allows the user to control simulation and view signal waveforms as the data is produced by the simulation. IVI is realized a an Eclipse plugin.
vtags for VIM Both perl and awk scripts to generate tag files for the VIM editor from your Verilog and VHDL source files, useful for browsing code and during code reviews.
Emacs VHDL mode The official Emacs VHDL mode home page. The mode includes syntax highlighting, indentation, templation insertion, word completion, customized menus, ... everything.
vim Newer versions of vim, a freeware vi clone, also include support support and syntax highlighting for VHDL.
VHDL editor with hierarchy tree A Tcl-based VHDL editor with syntax highlighting and a separate "explorer" style hierarchy browser, which also allows to quickly jump to a selected VHDL object (e.g. architecture).
nedit A freeware Unix editor with syntax highlighting for several programming languages, including VHDL.
PRISM editor An editor for Windows 95/98/NT with support for VHDL and several other languages, e.g. ABEL and Synopsys scripts. The editor is shareware; it will disable features after a trial period. The corresponding Windows based help file is free.
jGRASP A development environment, created specifically to provide automatic generation of software visualizations, improving the comprehensibility. jGRASP is implemented in Java, and runs on all platforms with a Java Virtual Machine (Java version 1.3 or higher).
jGRASP supports development in Java, C, C++, Ada, and VHDL, and it can be configured to work with almost any compiler.
Pretty Printing
mvp_v11 Make VHDL Pretty utility. (69K compressed tar).
MVPx A Windows frontend for MVP. Generates formatted Postscript from VHDL source code.
Some VHDL related tools fom the CRWU VLSI CAD Group: a pretty printer, a vhdl to HTML converter...
TimingTool TimingTool is a free graphical timing diagram editor, implemented as a Java applet. The editor uses TDML (timing diagram modelling language) as its data format and supports export to VHDL, Verilog, and text/graphics formats. As timing diagrams are stored on the TimingTool server, a user account with corresponding registration is required.
Ardid Ardid is a set of tools developed at the University of Madrid to help in the VHDL design flow of systems on silicon. It provides both a graphical front-end environment optimized for a VHDL design flow, and a set of tools to automatically check quality aspects of VHDL code. Ardid itself is free, but the tools rely on a commercial VHDL parser, which requires a licence. More details can be found in the papers about Ardid.
hdl2html A perl script to convert VHDL or Verilog into HTML code with color highlighting of keywords etc.
vsplit A tool to split design files into individual files for each entity, architecture, configuration (12K compressed tar).
vmkr A makefile generator (version 2.8) to be used in combination with vsplit (110K compressed tar).
blif2vhdl A BLIF to VHDL converter (51K compressed tar, with SunOS, Solaris, and Linux binaries. Source code (C++) included).
Brusey20 A FSM-schematic to VHDL code generator, with C sources (the MSC thesis of Thomas C. Mayo) The tool takes xfig drawings of FSMs and generates synthesizable VHDL code.
odlgen An awk script to automatically generate the case statement for the output decode logic process of an FSM (needs Gnu awk, example input file in the zip archive).