NAME

       netchange - format of netchange files read by irsim.

DESCRIPTION

       A  netchange  file  consists of a series of lines, each of which begins with a key letter.
       The key letter beginning a line determines how the remainder of the line  is  interpreted.
       The following are the list of key letters understood.

       | any text
              Lines  beginning  with  a  vertical  bar are treated as comments and ignored by the
              program.

       add type gate source drain length width [area]
              Add a new transistor of type to the network.  Currently, type may be:
                     n   n-channel enhancement transistor.
                     p   p-channel enhancement transistor.
                     d   depletion transistor (for NMOS).

              The names of the nodes to which the gate, source, and drain of the  transistor  are
              connected  are given by gate, source, and drain respectively.  The length and width
              of the transistor are given by length and width respectively.  The area  parameter,
              if  given,  will  use that number as the area for calculating the gate capacitance.
              Length and width should be given in lambda units, area should be in lambda^2 units,
              these  will  internally  be  multiplied by the LAMBDA factor from the configuration
              (.prm) file.

       delete type gate source drain length width [area]
              Delete an existing transistor from the net.   All  the  parameters  have  the  same
              meaning as for the add command.

       move type gate source drain length width [area] g s d
              Move  an existing transistor to a new location the net.  type, gate, source, drain,
              length, width, and area have the same meaning as for the add command.  g, s, and  d
              are the names of nodes to which the gate, source and drain should be connected.  If
              a particular terminal(s) is not to be re-connected, the name can be specified using
              an "*".  Any or all of g, s, and d may be "*".  For example, to move the gate of an
              n-channel transistor from node old to new the following command would be used:

                 m n old src_node drn_node 4 2.2 new * *

              Note that  the  drain  and  source  terminals,  and  the  g  and  s  terminals  are
              interchangeable; the simulator will know if these are swapped.  So the last example
              could also have been written:

                 m n old drn_node src_node 4 2.2 new * *

       capacitance node value
              Change the capacitance of a node by  value  picofarads.   Value  may  be  negative,
              thereby decreasing the node's capacitance.  Node is the node name.

       N node metal-area poly-area diff-area diff-perimeter
              Change  the  capacitance  of  node  using the area and perimeter information of the
              metal, polysilicon, and diffusion layers.  All the parameters should be  in  lambda
              (or lambda^2 for areas) units, they will internally be converted to the appropriate
              capacitance as defined in the configuration file.  The values can  be  negative  to
              decrease the capacitance.

       M node M2A M2P MA MP PA PP DA DP PDA PDP
              Change the capacitance of node, using the following geometrical information:

                     M2A   area of 2nd-level metal
                     M2P   perimeter of 2nd-level metal
                     MA    area of 1st-level metal
                     MP    perimeter of 1st-level metal
                     PA    area of polysilicon
                     PP    perimeter of polysilicon
                     DA    area of n-diffusion
                     DP    perimeter of n-diffusion
                     PDA   area of p-diffusion
                     PDP   perimeter of p-diffusion

              All  perimeter  values should be in lambda units, area values should be in lambda^2
              units.  The perimeter measures are half of the actual total perimeter  (i.e.,  they
              are  the  sum  of  the  lengths of the top and one side).  Again, the values may be
              negative to decrease the capacitance of the node.

       threshold node low high
              Change the threhsold voltages of node.   Low  and  high  should  be  in  normalized
              voltage units (i.e. floating-point numbers in the range 0.0 to 1.0).

       Delay node tplh tphl
              Change the delays for node to be tplh nanoseconds for low-to-high transistions, and
              tphl ns. for high-to-low transistions.   These  should  be  absolute  numbers,  not
              relative increments/dercrements.

       NOTE: For  all commands, only the first letter is significant, the rest of the string will
             be ignored.  They are only shown here for clarity.

BUGS

       This is an experimental interface for the incremental simulator  and  is  very  likely  to
       change in the future.

SEE ALSO

       irsim(5) sim(5) presim(1)