Atanua is a real-time logic simulator designed for educational use. It has an OpenGL accelerated user interface, with which the user can place components and wires. Components include all common logic blocks, including gates, latches and flip flops. Additionally Atanua simulates about 30 different 74-series chips, as well as an 8051 microcontroller variant. Simulated and pure logic parts can be mixed in the same circuit. On the I/O front, Atanua includes several different frequency clock inputs, constant level inputs as well as buttons that are bound to the user's keyboard. LEDs in various colors as well as 7-segment displays are also included. There is also a simple logic probe for debugging. The simulated parts are designed to resemble their real-world counterparts, which is more attractive for the students than pure schematics. The students can practice lab experiments using the simulated chips. The simulation shows the signal state of each wire in real time. In addition to high and low signal level, parts may output "invalid" signal, stating that there is a problem with the circuit, such as outputs connected together, or missing wirings from some chip. Additional parts can be made using the plug-in interface. As an example plug-in, a driver for the Velleman K8055 USB experiment board is provided, with which the user can mix simulated and real-world components. An anti-cheating tool is also available for teachers who wish to use Atanua for homework. Terms of license of Atanua are free for personal and noncommercial use. See license for details.
The BSIM Research Group in the Department of Electrical Engineering and Computer Sciences (EECS) at the University of California, Berkeley has developed BSIM (Berkeley Short-channel IGFET Model); it's a physics-based, accurate, scalable, robustic and predictive MOSFET SPICE model for circuit simulation and CMOS technology development. The third iteration of BSIM3 (commonly abbreviated as BSIM3v3), has since been widely used by most semiconductor and IC design companies world-wide for device modeling and CMOS IC design. All suggestions for model improvements are charted by the Compact Model Council (CMC). It is a consortium of semiconductor companies and simulator vendors world-wide promoting BSIM3v3 development as the industry standard compact model. The council is affliliated with Electronic Industries Alliance (EIA). In parallel, the BSIM research team has developed a compact model for SOI MOSFETs (BSIMSOI) which addresses several new issues in modeling sub-0.13 micron CMOS/SOI high-speed and RF circuit simulation. As extension of BSIM3, now there is BSIM4 which addresses the MOSFET physical effects into sub-100nm regime. Terms of license are BSD license.
GnuCAP (Gnu Circuit Analysis Package) is a general purpose mixed analog and digital circuit simulator. It performs;
AC analysis linearized at an operating point.
It is fully interactive and command driven. It can also be run in batch mode. The output is produced as it simulates. Spice compatible models for the MOSFET (levels 1-7) and diode are included. This project is not based on Berkeley Spice, but some of the models have been derived from the Berkeley models. GnuCAP is separately developed/maintained tools but associated with gEDA. There are, also, some package which contains the complete Berkeley simulator BSIM (there are no modifications to any of the BSIM code), Jspice a simulator for superconductor and semiconductor circuits (it is incorporated with the Josephson junction model) and a package with the complete set of models from NGSpice (version 17 at the moment). Terms of license of GnuCAP are GNU GPL version 2.
GNUSim8085 is a graphical cross platform simulator for the Intel 8085 microprocessor. it contains, also, an inline assembler and a debugger. You have to enter assembly code in order to use the simulator. It is having very user friendly graphical user interface; you have a seperate Data view widget to show variable values during debugging. GNUsim8085 can be used to test 8085 programs before actually implementing them on target board. Some features;
Variable declarations are supported in assembler;
Seperate Data view widget to show variable values during debugging;
Contents of memory, IO ports can be modified during program execution.