24 lines
1.3 KiB
Plaintext
24 lines
1.3 KiB
Plaintext
IRSIM is a tool for simulating digital circuits. It is a "switch-level"
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simulator; that is, it treats transistors as ideal switches. Extracted
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capacitance and lumped resistance values are used to make the switch a little
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bit more realistic than the ideal, using the RC time constants to predict the
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relative timing of events.
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IRSIM shares a history with magic, although it is an independent program. Magic
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was designed to produce, and IRSIM to read, the ".sim" file format, which is
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largely unused outside of these two programs. IRSIM was developed at Stanford,
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while Magic was developed at Berkeley. Parts of Magic were developed especially
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for use with IRSIM, allowing IRSIM to run a simulation in the "background"
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(i.e., a forked process communicating through a pipe), while displaying
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information about the values of signals directly on the VLSI layout.
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For "quick" simulations of digital circuits, IRSIM is still quite useful for
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confirming basic operation of digital circuit layouts. The addition of
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scheduling commands ("at", "every", "when", and "whenever") put IRSIM into the
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same class as Verilog simulators.
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To run irsim, users should set CAD_HOME to the base installation directory
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where magic was installed, e.g. /usr/local. Alternatively, the system
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administrator can create a dummy user named 'cad' with its home
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directory set to the installation directory.
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