ASTAP
Encyclopedia
ASTAP

was a general purpose analog electronic circuit
Analogue electronics
Analogue electronics are electronic systems with a continuously variable signal, in contrast to digital electronics where signals usually take only two different levels. The term "analogue" describes the proportional relationship between a signal and a voltage or current that represents the signal...

 simulator
Electronic circuit simulation
Electronic circuit simulation uses mathematical models to replicate the behavior of an actual electronic device or circuit.Simulation software allows for modeling of circuit operation and is an invaluable analysis tool...

 developed primarily for in-house use by IBM
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...

 from 1973

on. It was a powerful program used for simulation of integrated circuit
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...

 designs, and their analysis with statistical variations of the manufacturing process. In combination with the built-in Monte Carlo method
Monte Carlo method
Monte Carlo methods are a class of computational algorithms that rely on repeated random sampling to compute their results. Monte Carlo methods are often used in computer simulations of physical and mathematical systems...

 capabilities it allowed prediction of the performance of electronic circuits under a wide range of material parameters and temperatures. ASTAP was designed to run on IBM Mainframe computer
Mainframe computer
Mainframes are powerful computers used primarily by corporate and governmental organizations for critical applications, bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and financial transaction processing.The term originally referred to the...

s.

Unlike 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...

, which used Modified nodal analysis
Modified nodal analysis
In Electrical Engineering Modified Nodal Analysis or MNA is an extension of nodal analysis which not only determines the circuit's node voltages , but also some branch currents. Modified nodal analysis was developed as a formalism to mitigate the difficulty of representing voltage-defined...

 (MNA) to form the system of circuit equations, ASTAP instead used sparse tableau formulation (STA) to construct and solve a sparse matrix
Sparse matrix
In the subfield of numerical analysis, a sparse matrix is a matrix populated primarily with zeros . The term itself was coined by Harry M. Markowitz....

. The sparse tableau formulation produced very large, very sparse matrices which required special techniques to solve efficiently, even at that time. The advantage of STA for statistical analysis is that, as originally outlined, a subsequent analysis of a circuit with randomly varied parameters only required changing entries in the matrix.
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