CDL(10.6)                                               CDL(10.6)

     NAME
          cdl - circuit description language

     DESCRIPTION
          The circuit descriptions used by the various circuit design
          aid programs are expressed in dialects of CDL - the circuit
          design language described below.  This is half of a complete
          project specification; namely an electrical circuit with
          chips, pins and connecting signals.  The other half, a
          physical layout with pins and chip positions, is described
          in fizz(10.6) format.  The commands described below are rec-
          ommended; others exist and may work but are regarded as
          obsolete.

        Logic design
          A circuit consists of chips connected by signals. The point
          of connection is denoted by a pin. Each chip has a type
          which describes its logical and electrical characteristics.
          (For example, 74S181 is a chip type.)

          Types, signals, and chips are identified by name.  Pins  are
          identified by name and number.  A name is a string of let-
          ters, digits, or any of the characters +-.$/:<=>[]_.  Some-
          times, the first character may not be a digit.  A name may
          not be longer than 16 characters.

          In the following description, literals appear as
          constantwidth and names are in italic. [ ] enclose an
          optional item and a list of items is written

               {item}

          Commands are separated by either newline or semi-colon.  A
          comment starts with a % and ends with a newline and may
          appear on any line.  All white space serves only to separate
          tokens.

        General
          .f [ file ]
          Subsequent input originated in file . If file is not pre-
          sent, the previous file name is restored.

          .q
          End of file.

        Signal Description
          signal [ pin-number ] [ [ , ] pin-name ]
          name = signal
          Lines that do not start with a period are signal definition

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     CDL(10.6)                                               CDL(10.6)

          lines.  Signal definitions refer to the most recent .c com-
          mand.  The pin name and number refer to the chip.

        Circuit Description
          .c name [ [ , ] type ]
          Instantiates the chip name with type type. This is typically
          used for I/O connectors.  The command may occur more than
          once.  The type of a chip need only be specified once in a
          circuit description.  Signal descriptions that follow a .c
          command refer to pins on the chip.

          .c name = chip
          Establish name as a synonym for the previously defined chip.

          .m name1 name2
          Macro parameter definition.  The signal name1 is to be asso-
          ciated with macro parameter name2.

        Chip Type Description
          .t name package [pin] ...
          Define a chip type name. The name of the package in which it
          is installed, and pin numbers, pin, for the special signal
          connections are specified.  The special voltage pin numbers,
          if present, must be in the same sequence with which the spe-
          cial signals are numbered.  This usage is discouraged; use
          the .t[tT] commands described below.  (See .v command.)  All
          commands of the form .t?  are meant to follow a .t line.

          .t name = type
          name is a synonym for type .

          .tt sequence_of_single_character_pin_descriptors
          The number of characters must equal the numbers of pins on
          this type. The meaning of the descriptors is given in
          smoke(10.1).

          .tT sequence_of_single_character_pin_descriptors
          This means the same as the equivalent .tt command except
          that every [gvwxyz] pin must have a corresponding .vb pin.

          .tp name number ...
          The given pin name is associated with the pin number. Name
          may contain generators such as Q[0-7] which cause pin names
          Q0 ... Q7 to be assigned to the pin numbers given.  Multiple
          bracket constructs may be used.  In any case, the resulting
          list is lexicographically sorted before assigning to pin
          numbers.

     SEE ALSO
          cdm (10.1)

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