electric - Online in the Cloud

PROGRAM:

NAME

electric - a VLSI design system

SYNOPSIS

electric [OPTIONS]

DESCRIPTION

Electric is a general purpose system for all electrical design. It currently knows about
nMOS, CMOS, Bipolar, artwork, schematics, printed-circuit boards, and many other
technologies. It has a large set of tools including multiple design-rule checkers (both
incremental and hierarchical), an electrical rules checker, over a dozen simulator
interfaces, multiple generators (PLA and pad frame), multiple routers (stitching, maze,
river), network comparison, compaction, compensation, a VHDL compiler, and a silicon
compiler that places-and-routes standard cells.

In addition to the text terminal used to invoke the program, Electric uses a color display
with a mouse as a work station. Separate windows are used for text and graphics.

If a library disk file is mentioned on the command line, that file is read as the initial
design for editing. In addition, the following switches are recognized:

OPTIONS

-mdi
multiple document interface mode

-sdi
single document interface mode

-NOMINMEM
ignore minimum memory provided for JVM

-s <script name>
bean shell script to execute

-version
version information

-v
brief version information

-debug
debug mode. Extra information is available

-threads <numThreads>
recommended size of thread pool for Job execution.

-logging <filePath>
log server events in a binary file

-socket <socket>
socket port for client/server interaction

-batch
batch mode implies 'no GUI', and nothing more

-server
dump trace of snapshots

-client <machine name>
replay trace of snapshots

-help
this message

REPRESENTATION

Circuits are represented as networks that contain nodes and connecting arcs. The nodes
are electrical components such as transistors, logic gates, and contacts. The arcs are
simply wires that connect the nodes. In addition, each node has a set of ports which are
the sites of arc connection. A technology, then, is simply a set of primitive nodes and
arcs that are the building blocks of circuits designed in that environment.

Collections of nodes and arcs can also be aggregated into facets of cells which can be
used higher in the hierarchy to act as nodes. These user-defined nodes have ports that
come from internal nodes whose ports are exported. Facets are collected in libraries
which contain a hierarchically consistent design.

Arcs have properties that help constrain the design. For example, an arc may rotate
arbitrarily or be fixed in their angle. Arcs can also be stretchable or rigid under
modification of their connecting nodes. These constraints propagate hierarchically from
the bottom-up.

TECHNOLOGIES

A large set of technologies is provided in Electric. These can be modified with the
technology editor, or completely new technologies can be created. The following
paragraphs describe some of the basic technologies.

The nMOS technologies have arcs available in Metal, Polysilicon, and Diffusion. The
primitive nodes include normal contacts, buried contacts, transistors, and "pins" for
making arc corners. Transistors may be serpentine and the pure layer nodes may be
polygonally described with the node trace command. The "nmos" technology has the standard
Mead&Conway design rules.

The CMOS technologies have arcs available in Metal, Polysilicon, and Diffusion. The
Diffusion arcs may be found in a P-well implant or in a P+ implant. Thus, there are two
types of metal-to-diffusion contacts, two types of diffusion pins, and two types of
transistors: in P-well and in P+ implant. As with nMOS, the transistors may be serpentine
and the pure layer primitives may be polygonally defined. The "cmos" technology has the
standard design rules according to Griswold; the "mocmos" technology has design rules for
the MOSIS CMOS process (double metal); the "mocmossub" technology has design rules for the
MOSIS CMOS Submicron process (double poly and up to 6 metal); the "rcmos" technology has
round geometry for the MOSIS CMOS process.

The "schematic" technology provides basic symbols for doing schematic capture. It
contains the logic symbols: BUFFER, AND, OR, and XOR. Negating bubbles can be placed by
negating a connecting arc. There are also more complex components such as flip-flop, off-
page-connector, black-box, meter, and power source. Finally, there are the electrical
components: transistor, resistor, diode, capacitor, and inductor. Two arc types exist for
normal wires and variable-width busses.

The "artwork" technology is a sketchpad environment for doing general-purpose graphics.
Components can be placed with arbitrary color and shape.

The "generic" technology exists for those miscellaneous purposes that do not fall into the
domain of other technologies. It has the universal arc and pin which can connect to ANY
other object and are therefore useful in mixed-technology designs. The invisible arc can
be used for constraining two nodes without making a connection. The unrouted arc can be
used for electrical connections that are to be routed later with real wires. The facet-
center primitive, when placed in a facet, defines the cursor origin on instances of that
facet.

DESIGN-RULE CHECKING

The incremental design-rule checker is normally on and watches all changes made to the
circuit. It does not correct but prints error messages when design rules are violated.
Hierarchy is not handled, so the contents of subfacets are not checked.

The hierarchical checker looks all the way down the circuit for all design-rules. Another
option allows an input deck to prepared for ECAD's Dracula design-rule checker.

COMPACTION

The compactor attempts to reduce the size of a facet by removing unnecessary space between
elements. When invoked it will compact in the vertical and horizontal directions until it
can find no way to compact the facet any further. It does not do hierarchical compaction,
does not guarantee optimal compaction, nor can it handle non-manhattan geometry properly.
The compactor will also spread out the facet to guarantee no design-rule violations, if
the "spread" option is set.

SIMULATION

There are many simulator interfaces: ESIM (the default simulator: switch-level for nMOS
without timing), RSIM (switch-level for MOS with timing), RNL (switch-level for MOS with
timing and LISP front-end), MOSSIM (switch-level for MOS with timing), COSMOS (switch-
level for MOS with timing), VERILOG (Cadence simulator), TEXSIM (a commercial simulator),
SILOS (a commercial simulator), ABEL (PAL generator/simulator for schematic), and SPICE
(circuit level). MOSSIM, COSMOS, VERILOG, TEXSIM, SILOS, and ABEL do not actually
simulate: they only write an input deck of your circuit.

In preparation for most simulators, it is necessary to export those ports that you wish to
manipulate or examine. You must also export power and ground ports.

In preparation for SPICE simulation, you must export power and ground signals and.
explicitly connect them to source nodes. The source should then be parameterized to
indicate the amount and whether it is voltage or current. For example, to make a 5 volt
supply, create a source node and set the SPICE card to: "DC 5". Next, all input ports
must be exported and connected to the positive side of sources. Next, all values that are
being plotted must be exported and have meter nodes placed on them. The node should have
the top and bottom ports connected appropriately.

PLA GENERATION

There are two PLA generators, one specific to nMOS layout, and another specific to CMOS
layout. The nMOS PLA generator reads a single personality table and generates the array
and all driving circuitry including power and ground connections. The CMOS PLA generator
reads two personality tables (AND and OR) and also reads a library of PLA helper
components (called "pla_mocmos") and generates the array.

ROUTING

The router is able to do river routing, maze routing, and simple facet stitching (the
explicit wiring of implicitly connected nodes that abut). River routing runs a bus of
wires between the two opposite sides of a routing channel. The connections on each side
must be in a line so that the bus runs between two parallel sets of points. You must use
the Unrouted arc from the Generic technology to indicate the ports to be connected. The
river router can also connect wires to the perpendicular sides of the routing channel if
one or more Unrouted wires cross these sides.

There are two stitching modes: auto stitching and mimic stitching. In auto stitching, all
ports that physically touch will be stitched. Mimic stitching watches arcs that are
created by the user and adds similar ones at other places in the facet.

NETWORK COMPARISON

The network maintainer tool is able to compare the networks in the two facets being
displayed on the screen. Once compared, nodes in one facet can be equated with nodes in
the other. If the two networks are automorphic or otherwise difficult to distinguish,
equivalence information can be specified prior to comparison by selecting a component in
the first facet then selecting a component in the second facet.

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