AutoCAD Hatch Pattern File Location
The acad.pat & acadiso.pat files can be found stored in the locations listed below, alternatively type (findfile "ACAD.PAT") or (findfile "ACADISO.PAT") including the brackets on the command line to show the location.
AutoCAD 2000
C:\Program Files\AutoCAD\support
AutoCAD 2000i
C:\Program Files\AutoCAD\support
AutoCAD 2002
C:\Program Files\AutoCAD 2002\support
AutoCAD 2004
C:\Documents and Settings\[login name]\Application Data\Autodesk\AutoCAD 2004\enu\support
AutoCAD 2005
C:\Documents and Settings\[login name]\Application Data\Autodesk\AutoCAD 2005\enu\support
AutoCAD 2006
C:\Documents and Settings\[login name]\Application Data\Autodesk\AutoCAD 2006\enu\support
AutoCAD 2007
C:\Documents and Settings\[login name]\Application Data\Autodesk\AutoCAD 2007\enu\support
AutoCAD 2008
C:\Documents and Settings\[login name]\Application Data\Autodesk\AutoCAD 2008\enu\support
AutoCAD 2009
C:\Documents and Settings\[login name]\Application Data\Autodesk\AutoCAD 2009\enu\support
AutoCAD 2010
C:\Documents and Settings\[login name]\Application Data\Autodesk\AutoCAD 2009\enu\support
AutoCAD 2011
C:\Documents and Settings\[login name]\Application Data\Autodesk\AutoCAD 2011\enu\support
AutoCAD 2012
C:\Documents and Settings\[login name]\Application Data\Autodesk\AutoCAD 2012\enu\support
AutoCAD 2013
C:\Documents and Settings\[login name]\Application Data\Autodesk\AutoCAD 2013\enu\support
AutoCAD 2014
C:\Users\\AppData\Roaming\Autodesk\AutoCAD 2014\Rxx.x\enu\Support
AutoCAD 2015
C:\Users\\AppData\Roaming\Autodesk\AutoCAD 2015\Rxx.x\enu\Support
AutoCAD 2016
C:\Users\\AppData\Roaming\Autodesk\AutoCAD 2016\Rxx.x\enu\Support
AutoCAD 2017
C:\Users\\AppData\Roaming\Autodesk\AutoCAD 2017\Rxx.x\enu\Support