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XSPICE is an extended and enhanced version of the popular SPICE analog circuit simulation program originally developed at the University of California at Berkeley. XSPICE was developed at the Georgia Tech Research Institute (GTRI, project headed by Fred Cox) as a tool for simulating circuits and systems at multiple levels of abstraction. XSPICE permits a user to simulate analog, digital, and even non-electronic designs from the circuit level through the system level in a single simulator.
A special Code Modeling feature allows users to add new models directly into the simulator executable for maximum simulation speed and accuracy. Code models are written in the C programming language allowing arbitrarily complex behavior to be described. Code model development tools are provided to simplify the process of creating new models, compiling them, and linking them with the XSPICE core.
XSPICE provides a rich set of predefined code models in addition to the standard discrete device models available in SPICE. The XSPICE code model library contains over 40 new functional blocks including summers, multipliers, integrators, magnetics models, limiters, S-domain transfer functions, digital gates, digital storage elements, and a generalized digital state-machine.
Digital functions are simulated in XSPICE through an embedded event-driven algorithm added to the SPICE core. This algorithm is coordinated with the analog simulation algorithm to provide fast and accurate simulation of mixed-signal circuits and systems. The event-driven algorithm supports a new "User-Defined Node" capability allowing additional event-driven data types to be defined and used. XSPICE comes with a 12-state digital data type as well as a user-defined node library that includes 'real' and 'integer' types useful in simulating sampled-data systems such as digital signal processing algorithms.
XSPICE was developed on HP/Apollo series workstations (DN3XXX, DN4XXX, and Series 400 models) running BSD4.3 UNIX and the X Window System, release 4 with the Athena Widget set. An ANSI compatible C compiler is required to compile the program. The program has also been successfully compiled on Sun workstations with ANSI compatible C compilers and compatible X Window System software.