1.0)	Introduction
                                         
	This file describes the new features and changes included in the 5.1
	release of PSpice for DOS.  PSpice, running under low memory DOS,
	will allow you to simulate a circuit of about 300 nodes and
	120 transistors.  Low memory DOS platforms are strictly analog, 
	therefore this README.DOC file does not include any digital
	information.
	

2.0)	Program Modifications since Version 5.0


	***PSpice***

	1.  Fourier Analysis  (.FOUR command)

		The .FOUR command for Fourier analysis now allows an
		argument to specify the number of harmonics you wish
		to have calculated.  

		The general format is:
		
		.FOUR  [no. harmonics value] *

		For example:
		
		.FOUR 60Hz 20 V(17)

		If the number of harmonics is not specified, the DC
		component, fundamental, and 2nd through 9th harmonics
		are calculated by default.

	        Refer to Chapter Three, page 62 of the Analysis Reference
		Manual for information on the .FOUR command.


	2.  Lossy Transmission Line Model

		A Lossy Transmission Line model has been implemented in 
		version 5.1.  Using the distributed model approach rather
		than the the traditional lumped model approach allows you
		to simulate lossy lines in a significantly reduced amount
		of time.  

		The general format is:

		T		  
		+		  
		+		LEN= R= L=
		+		G= C=

		For examples, refer to Chapter Four, page 127, of the 
		Analysis Reference Manual.


        ***Probe***

        1.  Remove_trace
                
                Changes have been made to allow one or more traces to be
		selected for removal, before actually removing the traces
		(and doing the sometimes time consuming redraw of the
		display).

                The traces to be removed may be selected by using either the
                mouse or the arrow keys and space bar.  Selected traces are 
                marked with a '<' to the right of the trace name
		( e.g. V(4)< ).

                Using the mouse:
                  Clicking on the trace name the first time selects the trace.
                  Clicking on the trace again deselects it.

                Using the arrow keys and space bar:
                  When select is chosen, the first trace is highlighted.  The
                  right and left arrows will move the highlight to other trace
                  names.  The space bar selects/deselects the trace.

                Also, an Undelete command has been added.  It will redisplay
                the last trace(s) deleted since entering the Remove_trace menu.
                Undelete only appears in the menu if traces have been deleted
                since entering the Remove_trace menu.

                NOTE: because of these changes, Probe command files created by
                Probe 5.0 or earlier, will no longer work for deleting traces.


        2.  Goal function search commands:

                Limited expressions have been added for LEVEL(val),
                and XVALUE(val).

                In 5.0, val could be:
                  a floating number  (e.g. 1e5, 100n, 1, ...)
                  a percent (e.g. 50%)
                  a marked point (e.g. x1, y1, ...)

                In 5.1, val can also be:
                  a db value relative to max or min
                    max-3db or -3db => 3db below maxrng
                    min+3db or  3db => 3db above minrng
                  a value relative to max or min
                    max-3 => maxrng - 3
                    min+3 => minrng + 3
                  a relative db value
                    .-3db => 3db below lastvalue
                    .+3db => 3db above lastvalue
                  a relative value
                    .-3   => lastvalue - 3
                    .+3   => lastvalue + 3

                  where lastvalue is the x or y value found by the last search 
                  command.  For the first search command, lastvalue is the 
                  starting point for the first search command.
                
		  For more information on Search_commands, see page
		  320 of the Analysis Reference Manual.
    	

	***Parts***

	1.  Non-linear Magnetic Core Model

		A non-linear magnetic core model has been added and uses
		a derivative of the Jiles-Atherton formulation to provide
		a closed-form, analytic solution.  For detailed information,
		please refer to Chapter Eight, page 414, of the 
		Analysis Reference Manual.


	3.0  Analog Library Additions Since Version 5.0

	The following libraries have been added to the 5.1 version 
	of PSpice:

	-  European-manufactured semiconductor devices: EUROPE.LIB
           Note: Some of the devices in EUROPE.LIB and their counterparts
 	   in the regular libraries (e.g. DIODE.LIB) have identical names.
	   In order for PSpice to find the correct model/subcircuit
	   definition, you must ensure that the appropriate library is
	   specified first in NOM.LIB.

	   If EUROPE.LIB is specified before another model library
	   containing duplicate names, none of the duplicate devices
	   in the second library will be accessed.  Therefore, if
	   D1N4148 and D1N4149 exist in both EUROPE.LIB and DIODE.LIB, 
	   PSpice would take both the D1N4148 and D1N4149 definitions
	   from EUROPE.LIB which is listed before DIODE.LIB in NOM.LIB.
	   To avoid this from happening you can extract the specific
	   devices from the desired libraries and put them into a library
	   that is listed before any other library containing the device
 	   with the duplicate name.

	-  RCA/GE/Harris power-transistor devices: HARRIS.LIB

	-  Averaging power supply devices: SWIT_RAV.LIB
	   Note: The Average Power Supply Model listed in the library list 
	   pamphlet as VMSSDCM is not currently available in the library.