Shareware Overload Trio 2/Shareware Overload Trio Volume 2 (Chestnut CD-ROM).ISO/dir30/pcbview.zip/GCPREVUE.DOC

Text File | 1993-07-29 | 124KB | 3,943 lines

                   GC-PREVUE(TM)

                 The Photoplot Data Viewer



                   User's Guide




     Copyright (C) GraphiCodeTM, Inc. 1987, 1988, 1989, 1990, 1991.
     All rights reserved.

     LICENSING AGREEMENT

     Shareware License Statement

     GraphiCode, Inc. grants you, the possessor of a GC-PREVUE program
     diskette, the right to make copies of this GC-PREVUE diskette,
     and to distribute copies of this diskette with the following
     restrictions and requirements:

     You must distribute ALL the GC-PREVUE files on this diskette at
     the same time.  This diskette contains the files MAKEPVU.EXE and
     a README file that includes this License Statement.

     You may put the GC-PREVUE files on this diskette on a network or
     BBS as long as the contents are unchanged.

     You may distribute the GC-PREVUE files ONLY in the compressed
     form in which you received them on this diskette.  You may NOT
     distribute the files that load onto your hard drive as a result
     of running the MAKEPVU.EXE decompression program.

     You must NOT modify any GC-PREVUE files or add any files to the
     diskette you distribute.

     You may sell copies of this GC-PREVUE diskette, but only at a
     price that does not exceed the cost of reproduction and
     distribution.  If you advertise any GC-PREVUE diskettes, you must
     identify "GC-PREVUE" as a trademark of GraphiCode, Inc.

     You must NOT copy or distribute printed copies of the on-disk GC-
     PREVUE manual, or the printed GC-PREVUE manual published by
     GraphiCode, or any portion of those printed manuals.

     GC-PREVUE is the only GraphiCode product distributed as
     "shareware".  You may NOT make copies of other GraphiCode
     software.

     You don't need to notify GraphiCode when you distribute copies of
     GC-PREVUE according to these rules.

     For user support call GraphiCode Technical Support at (206) 771-
     5600 or our technical support BBS at [phone].  To order
     printed copies of the GC-PREVUE user manual, or for more
     information about GraphiCode products, contact us at (206)-672-
     1980.  Our fax number is [phone].  Our address is:

     19101 36th Avenue West, Suite 204
     Lynnwood WA 98036
     USA




     GC-PREVUE programs and manual are Copyright (C) 1987-1991
     GraphiCode, Inc.  GraphiCode, GC-, and GC-PREVUE are trademarks
     of GraphiCode, Inc.

     The information in this manual is subject to change at any time.

     Rev. D4 May, 1992

     The following terms used in this manual are the trademarks of the
     indicated companies:  MS-DOS, Microsoft Corp.; PC-DOS, IBM, IBM-
     PC,XT,AT,PS/2, International Business Machine Corp.; Hercules,
     Hercules Computer Technology; Gerber, The Gerber Scientific
     Instrument Co.; HPGL, Hewlett-Packard; Postscript, Adobe Systems
     Inc.; Quest and Emma, Marconi Quest CAE; Excellon, Excellon
     Automation.


    OTHER GRAPHICODE PRODUCTS

    We hope you enjoy using GC-PREVUE.  If your only task is checking
    your CAD output, then you may not need any other GraphiCode
    product.  However, if you need to edit CAD output, combine files
    or further prepare a PCB design for manufacturing, then you
    should know about some other GraphiCode products, GC-PREDITOR,
    GC-PREP, and GC-CAM.

    GC-PREDITOR, GC-PREP and GC-CAM incorporate all of GC-PREVUE's
    input/view/checkplot features, and introduce powerful editing and
    automated data checking capabilities.  All these products load GC-
    PREVUE .PWK design files for easy data transfer, creating an
    ideal workgroup or customer support system.  For more information
    on these GraphiCode products, please read on below.


    GC-PREDITOR: POWERFUL PCB DATA EDITOR

    GC-PREDITOR is not just a "Gerber editor" - it's a complete PCB
    data editor.  GC-PREDITOR lets you view and edit all popular PCB
    data formats simultaneously.  In addition to its multiple input
    formats, GC-PREDITOR can output to virtually any X Y device,
    including photoplotters, penplotters, NC drill and rout machines,
    AutoCAD scripts, and more.  GC-PREDITOR features the most
    powerful editing and panelizing features available in "Gerber
    editing".

    GC-PREDITOR Features:

    * Superset of GC-PREVUE
    * NC Drill data support: In/Out/Generate/Edit/Optimize
    * WYSIWYG custom apertures on ANY photoplotter
    * User-defined formats for output to any X Y device
    * Intelligent rotation of asymmetrical pads
    * Step & Repeat (array copy) by window
    * Mirror by window or layer in either axis
    * Offset data by layer/window/individually
    * Stretch traces individually/window
    * Copy and delete data individually/window
    * Transcode plot entities by window/globally
    * Create new traces and pad stacks
    * Create text in any size or orientation
    * Prints screen graphics to Epson, HP LaserJet, etc.



    GC-PREP: PCB DATA PREPROCESSING FOR DESIGNERS

    Sometimes you need to do more with your data to get it ready for
        manufacturing.  GC-PREP adds the CAM features most requested by PCB
        designers who want control over the manufacturing preprocessing of
        their data.

    Completely upward compatible with GC-PREVUE and GC-PREDITOR,
    GC-PREP features all of GC-PREDITOR's editing capabilities and adds
    sophisticated data preparation capabilities to your PC.

    GC-PREP Features:

    * Superset of GC-PREDITOR
    * 80386 Protected Mode Workstation (80x86, too)
    * Design Rule Check with interactive graphics
    * Sketched pad to flash conversion
    * Inner layer unused pad removal
    * Silkscreen clipping
    * Removal of features buried by other features
    * NC drill and rout capabilities, including sequencing
    * Automatic solder mask creation
    * 99 layers
    * 10 aperture lists, with up to 999 apertures each
    * Loads GC-PREVUE and GC-PREDITOR design files
    * And much more! Call for details


    GC-CAM: TRUE CAM ON A PC

    GraphiCode's True CAM software checks to make sure that the PCB
    is manufacturable, and corrects deficiencies in the original CAD
    data.  With its highly flexible design, powerful editing, and
    rapid processing, GC-CAM keeps your work flowing - maximizing
    throughput, minimizing errors.  Board manufacturers, film service
    bureaus and sophisticated design groups find GC-CAM invaluable.

    Completely upward compatible with GC-PREVUE, GC-PREDITOR, and
    GC-PREP, GC-CAM features all of GC-PREP's editing capabilities
    and adds sophisticated CAM capabilities to your PC.

    GC-CAM Features:

    * Superset of GC-PREP
    * 80386 Protected Mode CAM Workstation (80x86, too)
    * Complete Automatic panelization:
         Panel optimization
         Venting patterns: starburst, hatch, crosshatch, dot
         High level step & repeat to aid NC machines
         Automatic deletion of unused inner-layer pads
    * Accurate copper area calculation
    * NC drill and rout capabilities, including:
         toolwidth compensation
         sequencing
    * Convert vector-filled ground planes to polygons, and vice versa
    * Netlist extraction for ATE
    * Optional test fixturing for ATE
    * Optional Direct Write outputs for embedded aperture lists and
      positive/negative layer merges for:
          -  MDA Fire AutoPlot
          -  Disc (Barco) DPF
          -  Gerber RS-274-X
          -  EIE Extended Gerber
          -  Secma .R
          and others...
    * Loads GC-PREVUE, GC-PREDITOR and GC-PREP design files
    * And much more! Call for details

    FOR MORE INFORMATION OR DEMONSTRATION PROGRAMS:
    Contact GraphiCode at [phone], FAX [phone],
    BBS MODEM [phone]

                                i




     Table of Contents
     _________________________________________________________________



     1.

     Introducing GC-PREVUE           1

        1.1 What GC-PREVUE Does          1

        1.2 GC-PREVUE Features:          2

        1.3 About This Manual        2

        1.4 Getting Help             2

        1.5 The History of GC-PREVUE     3


     2.

     Getting Started with

     GC-PREVUE                   4

        2.1 System Requirements          4

        2.2 Installing GC-PREVUE         4

        2.3 Starting the Program         4
           2.3.1 If GC-PREVUE Does Not Run   5

        2.4 Leaving the Program          5

        2.5 Disk-Based Virtual Memory    5


     3.

     GC-PREVUE Basics            7

        3.1 Ctrl and Alt             7

        3.2 Using a Mouse            7
           3.2.1 Clicking            7
           3.2.2 Dragging            7

        3.3 Esc and Ctrl Break           8

        3.4 Getting Help             8
           3.4.1 The Help Line           8
           3.4.2 ClickCenter or Ctrl M for Menu   8


         ii               GC-PREVUE User's Guide



        3.5 Using Menus              9
           3.5.1 Horizontal Menus        9
           3.5.2 Vertical Menus          9

        3.6 Working with Data Input Windows  9
           3.6.1 Moving from Field to Field  10
           3.6.2 Editing a Data Field    10
           3.6.3 Toggles (Limited Choice Data Fields)  10
           3.6.4 Units (Ctrl U)          10
           3.6.5 Scrolling Large Lists       10
           3.6.6 Printing Lists (Alt P)      11

        3.7 Special Features for Filename Entries 11
           3.7.1 Interactive Directories     11
           3.7.2 Default Filename Extensions 11
           3.7.3 Hardware Devices as Output Files 12

        3.8 Perform a DOS Command (Ctrl C)   12


     4.

     GC-PREVUE Configuration         13

        4.1 Load a Configuration         13

        4.2 Save the Configuration       13

        4.3 Bed Size             14

        4.4 Reminder Interval        14

        4.5 Graphics Display Type        14

        4.6 Beep                 15

        4.7 Mouse Sensitivity        15


     5.

     Aperture Lists              16

        5.1 Special Aperture List Features   16
           5.1.1 Aperture Position       16
           5.1.2 Aperture Code           16
           5.1.3 Drill               16
           5.1.4 Rotate +/-90 (R90)      16
           5.1.5 Dimensions          17
           5.1.6 Aperture Type           17
           5.1.7 Invisible Apertures     17

        5.2 Working with Aperture Lists      18
           5.2.1 Load/Create an Aperture List (F1)     18


                                   iii



           5.2.2 Unload an Aperture List (Ctrl F1)     18
           5.2.3 Edit an Aperture List (F2)  18
           5.2.4 Inspect an Aperture List (F3)    19
           5.2.5 Write an Aperture List to Disk (F4)   20
           5.2.6 Copy & Resize an Aperture List (F5)   20


     6.

     The Drill Rack              21

        6.1 Special Drill Rack Features      21
           6.1.1 Diameter            21
           6.1.2 Invisible Drills        21

        6.2 Working with the Drill Rack      21
           6.2.1 Load a Drill Rack       22
           6.2.2 Save the Drill Rack     22
           6.2.3 Edit the Drill Rack     22
           6.2.4 Make a New Drill Rack       22


     7.

     Working with Plotter and

     NC Data                 23

        7.1 The Layer List           23
           7.1.1 Status: Empty or Loaded     23
           7.1.2 Offset(inch/mm) X,Y     23
           7.1.3 Aperture List ("Aps")       23
           7.1.4 Layer Polarity          24
           7.1.5 Filename            24

        7.2 Loading Layers from Data Files   25
           7.2.1 Gerber, NC Drill and NC Rout Files    26
           7.2.2 HPGL Files          29
           7.2.3 Quest Files         30
           7.2.4 Automatic File Format Detection  30

        7.3 Working with the Layer List      31
           7.3.1 Load (F1)           31
           7.3.2 Unload Layers (Ctrl F1)     31
           7.3.3 View Layer(s) (F2)      31
           7.3.4 Layer Report (F3)       31
           7.3.5 CheckPlot (Alt F4)      32
           7.3.6 Copy Layers (F5)        32
           7.3.7 Copy NC (Ctrl F5)       33
           7.3.8 Save All Work (F6)      33
           7.3.9 Restore All Work (F7)       33
           7.3.10 Move Layer to Top of List (F8)  33
           7.3.11 Set Layer Color (F9)       34
           7.3.12 Set... (Ctrl S)        34


         iv               GC-PREVUE User's Guide



           7.3.13 Set Display Units (Ctrl U) 34
           7.3.14 Print Layer List (Alt P)   34


     8.

     View Data                   35

        8.1 The Viewer Display           35
           8.1.1 The Help Line           35
           8.1.2 Absolute X,Y        35
           8.1.3 Relative X,Y        36
           8.1.4 Grids: Step, Snap, & Show   36
           8.1.5 Setup               36

        8.2 Basic Editing Concepts       37
           8.2.1 Getting Help        37
           8.2.2 Getting Out of the Viewer   37
           8.2.3 Saving Your Work (F6)       37
           8.2.4 Preparing to View:
           Hide or View              37
           8.2.5 Speed-up Keys (1...9)       37

        8.3 Commands for Viewing         38
           8.3.1 Undo (U)            38
           8.3.2 Offset (O)          38
           8.3.3 Rotate (R)          38
           8.3.4 Mirror X/Y data (X) (Y)     39

        8.4 Panning and Zooming          39
           8.4.1 Pan the Display (DragCenter or P)     39
           8.4.2 Zoom In (ClickLeft or +)    39
           8.4.3 Zoom Out (ClickRight or -)  39
           8.4.4 Unzoom (Alt -)          39

        8.5 Drawing              39
           8.5.1 reDraw Now (D)          39
           8.5.2 Drawing Mode (Ctrl D)       40
           8.5.3 Label Apertures (L)     41
           8.5.4 Wait Between Layers (W)     41
           8.5.5 Aspect Ratio (Ctrl A)       41

        8.6 Grid                 42
           8.6.1 User-Defined Grid (Alt G)   42
           8.6.2 Change the Step Grid Size (F1/F2)     42
           8.6.3 Change the Snap Grid Size
           (Ctrl F1/Ctrl F2)         43
           8.6.4 Snap to Grid (G)        43
           8.6.5 Turn Grid Markers On/Off (Ctrl G)     43
           8.6.6 Freehand Mouse (F)      43
           8.6.7 Zero the Relative Readout (Z)    43
           8.6.8 User Zero (Alt Z)       43
           8.6.9 Units mm/inch (Ctrl U)      43


                                v



        8.7 Miscellaneous Commands       44
           8.7.1 Query (Q)           44
           8.7.2 Bed Size (Ctrl B)       44
           8.7.3 Inspect Aperture Lists and
           the Drill Rack (F10)          44
           8.7.4 Jump to Absolute X,Y (J)    45
           8.7.5 Jump to Relative X,Y (Alt J)     45


     Appendix A: APER

     The GraphiCode Custom

     Aperture Generator              46

        A.1 How GC-PREVUE Uses Custom Apertures   46

        A.2 Using APER to Create Custom Apertures 46
           A.2.1 APER Basics         46
           A.2.2 CAT Files and CAP Files     46

        A.3 Starting APER            47
           A.3.1 Custom Aperture Text Descriptions     47
           A.3.2 The CAT Data Header     48
           A.3.3 CAT Syntax          50
           A.3.4 Differences Between CAT Syntax
           and HPGL              51

        A.4 APER Macro Feature           52
           A.4.1 Help            52
           A.4.2 Merge               52
           A.4.3 Macro Commands Supported    53
           A.4.4 Custom Aperture Macro Syntax     53

        A.5 View Custom Apertures While You Edit  62
           A.5.1 Aper Viewing Features       62

        A.6 Custom Apertures in Aperture Lists    63


     Index                   64


         vi               GC-PREVUE User's Guide



     Table of Figures
     _________________________________________________________________



     Figure 2.1

        GC-PREVUE's Startup Screen       5


     Figure 4.1

        Configuration File Input Window      14


     Figure 5.1

        Aperture List Edit Screen        19


     Figure 7.1

        GC-PREVUE Loading Format Options     26


     Figure 7.2

        Layer List Menu              31


     Figure 8.1

        GC-PREVUE Viewer Screen          35


     Figure 8.2

        Commands for Editing         38


     Figure 8.3

        Drawing Options              40


     Figure 8.4

        User-defined Grid            42


     Figure 8.5

        Query Feature            44


                                   vii




     Figure A.1

        APER Custom Aperture Generation Screen    47


     Figure A.2

        Supported HPGL & CAT Commands    50


     Figure A.3

        Oval                 53


     Figure A.4

        Octagon                  54


     Figure A.5

        Annulus                  55


     Figure A.6

        Moire                56


     Figure A.7

        Crosshair                57


     Figure A.8

        Quad                 58


     Figure A.9

        Double Quad              59


     Figure A.10

        Round Thermal            60


     Figure A.11

        Square Thermal               61


         viii             GC-PREVUE User's Guide

         1: Introducing GC-PREVUE               1
         _______________________________________________________

     1.
     Introducing GC-PREVUE
     _________________________________________________________________


     1.1 What GC-PREVUE Does

     GC-PREVUE is CAD/CAM software designed to help you work more
     efficiently with RS-274 (often called "Gerber") photoplotter and
     NC drill CAD output data, with a particular emphasis on Printed
     Circuit Board applications.  GC-PREVUE also supports HPGL and
     Quest (Marconi Emma) plotter formats.

     By verifying your CAD data from the photoplotter's point of view
     you will save time, money and headaches due to miscommunication
     with your photoplotting service and fabrication facilities.

     Job files prepared using GC-PREVUE are fully compatible with
     GraphiCode's PCB CAM software GC-CAM and its many OEM cousins,
     and GraphiCode's PCB data editor GC-PREDITOR.  Contact your
     photoplotting bureau or PCB fabrication house to see if they
     accept jobs in GC-PREVUE .PWK format.  At the very least, feel
     free to offer them a copy of GC-PREVUE so that they can receive
     your aperture lists more easily.

     GC-PREVUE job files contain all layer data, aperture lists
     (including custom aperture shapes) and drill information needed
     to effectively communicate with your photoplotting vendor and
     fabrication house.

         2                 GC-PREVUE User's Guide
         _______________________________________________________

     1.2 GC-PREVUE Features:

       Input of all popular PCB-related data formats, including:
          Gerber; HPGL; Quest/Emma; Excellon; Sieb & Meyer
       Multi-Layer Data Viewing
          Up to 35 layers, 12 assignable colors
          Up to 10 aperture lists
          Traces, pads and holes shown at size
          True WYSIWYG custom apertures
          Positive/Negative/Composite data layer polarity
          Support for most popular aperture shapes
          Supports rectangular drawing apertures
          Windowed zoom
       Data Manipulation for Viewing
          Shift by window or Layer
          Rotate by window or Layer
          Intelligent rotation of asymmetrical pads
          Mirror (both axes) by window or Layer
       Check Plot: Output user-defined scaled graphics to
          HPGL and Postscript
       Disk-based Virtual Memory - Unlimited file size!
       LIM EMS Expanded Memory Support
       Instant Access to any DOS program or command
       Built-in Directory for easy file loading

     GC-PREVUE is designed for ease of use, with an intuitive
     graphics-based Viewer and commands that work with either a single
     keystroke or from a menu.

     1.3 About This Manual

     This manual is written to get you working as quickly as possible.
     We recommend that you discover GC-PREVUE's power by running the
     software while you read this manual.  The sections listed below
     are especially recommended to help get you up and running:

       Section 2 - Installing the program
       Section 3 - Basic GC-PREVUE operation
       Section 5 - Aperture lists
       Section 7 - Working with plotter and NC data
       Section 8 - Inspecting data

     Feel free to print this manual for your own use.  If you would
     like to purchase a printed copy of this manual, contact
     GraphiCode or your local GraphiCode representative.

     1.4 Getting Help

     If you need further help with GC-PREVUE, you can contact
     GraphiCode Technical Support at [phone] or call our
     technical support BBS at [phone] (Courier HST high speed
     modem - 1200/2400/9600 Baud - No Parity, Eight Bits).

         1: Introducing GC-PREVUE               3
         _______________________________________________________

     1.5 The History of GC-PREVUE

     Since its introduction in 1987, GC-PREVUE has been helping people
     who work with PCB CAD output data to develop a better
     understanding of that data.  By giving the CAD operator and the
     photoplotter operator the ability to inspect the data before
     plotting, countless pieces of bad film have been avoided.

     Beginning with GC-PREVUE Version 5.0, GraphiCode is releasing GC-
     PREVUE as "Shareware" as a service to the PCB industry.  This
     means that you are encouraged to use the software and pass it to
     your friends and co-workers.  Mostly we just want to be sure that
     you to distribute the complete kit - please read the Shareware
     license for the very few restrictions that do apply.  GraphiCode
     does not want you to pay for the use of GC-PREVUE, but does
     reserve the right to sell printed manuals.

     By easing access to CAD output data verification tools,
     GraphiCode is making a contribution to the PCB industry by
     helping to educate CAD operators in the nature of CAD output data
     and its pitfalls.  Understanding the problem is half the battle.

         2: Getting Started with GC-PREVUE          4
         _______________________________________________________

     2.
     Getting Started with
     GC-PREVUE
     _________________________________________________________________


     2.1 System Requirements

     GC-PREVUE requires:

       IBM PC/XT/AT/PS-2 or compatible
       MSDOS or PCDOS version 2.0 or higher
       Hercules, CGA, EGA, VGA, SuperVGA, or Hi Res (1024x768)
       compatible graphics


     GC-PREVUE is recommended for use with:

       80286/80386 (AT-class) systems
       80x87 math coprocessor
       hard disk drive
       EGA, VGA, SuperVGA, or Hi Res (1024x768) color graphics
       Microsoft-compatible mouse or equivalent (two or more buttons)

     2.2 Installing GC-PREVUE

     Just make a new directory, if necessary, and copy the various GC-
     PREVUE files into it.  We suggest you create a new directory
     called "C:\GC-PREVUE", but any name will do.  It is a good idea
     to change your AUTOEXEC.BAT file so that the GC-PREVUE directory
     is automatically included in the PATH when your computer is
     turned on.  Consult your DOS manual for more information.

     2.3 Starting the Program

     To start GC-PREVUE, just type:

       GCPREVUE

     If you have certain data files in mind, you can add them to the
     command.  Here is an example:

       GCPREVUE  DEMODAT1.GBR  DEMODAT2.GBR

     If you want to use a certain GC-PREVUE configuration (see Section
     4) you can specify that too.  For example, to use "MYCONFIG.PED",
     type:

         2: Getting Started with GC-PREVUE          5
         _______________________________________________________

       GCPREVUE  /MYCONFIG



















              Figure 2.1: GC-PREVUE's Startup Screen

     2.3.1 If GC-PREVUE Does Not Run

     Common problems include insufficient memory due to too many
     memory resident programs (TSRs), or incompatibility with off-
     brand "clone" PCs.  Try rebooting your system without any TSRs
     loaded.

     2.4 Leaving the Program

     In GC-PREVUE you can always get out of whatever you are doing by
     pressing the Esc or Ctrl Break key.  In the main menu, either Esc
     or the Exit option will get you out of GC-PREVUE and back to DOS.
     GC-PREVUE will ask you if you REALLY want to exit the program -
     just press Y or Enter.  Y(es) is the default entry, so make sure
     you press N(o) if you do not wish to leave GC-PREVUE.

     2.5 Disk-Based Virtual Memory

     One particularly useful feature of GC-PREVUE is its ability to
     use the disk for temporary storage ("virtual memory") when RAM
     and EMS memory are exhausted.  This means that you never
     encounter the dreaded "Out of Memory" error message unless you
     run out of disk space as well.  You can tell GC-PREVUE where to
     keep its temporary disk files by setting the environment variable
     "TMP".  For example, you might set up a directory "c:\scratch".
     You could then type at the DOS ">" prompt:

       SET  TMP=C:\SCRATCH

     If for some reason GC-PREVUE can't access the directory referred
     to by TMP, or the TMP environment variable is not set, then the
     temporary file will be written to the current directory.  In any

         6                 GC-PREVUE User's Guide
         _______________________________________________________

     event, the file will be removed at the end of the GC-PREVUE
     session.

         3: GC-PREVUE Basics                7
         _______________________________________________________

     3.
     GC-PREVUE Basics
     _________________________________________________________________


     This section will tell you what little you need to know about the
     GC-PREVUE operating environment, in order to get you moving.

     While GC-PREVUE works with Hercules monochrome graphics adaptors,
     color devices are preferred (they convey more information).  The
     CGA display is driven in its highest resolution mode, which is
     also black and white.

     Note: Keystrokes in this User's Guide are shown in Boldface type.
     The GC-PREVUE Guide to Keystrokes, included in your purchase of a
     GC-PREVUE User's Guide, provides a list of the keystrokes you
     will need to operate GC-PREVUE easily.

     3.1 Ctrl and Alt

     In GC-PREVUE, some single key commands are actually a combination
     of two keys pressed simultaneously.  When you see, for instance,
     a reference to Ctrl M, what is meant is the combination of the
     Ctrl and M keys pressed at the same time.  Similarly, Alt M
     refers to the Alt and M keys being pressed at the same time.  GC-
     PREVUE makes no distinction between upper and lower case letters.

     3.2 Using a Mouse

     The use of a mouse as a pointing device greatly eases the
     operation of GC-PREVUE.  In this section we review a few basic
     mouse terms and concepts.

     3.2.1 Clicking

     The act of "clicking" is simply the pressing and releasing one or
     more of the mouse buttons without moving the mouse.  On two-
     button mice, the third button is emulated by using both button
     simultaneously.  There are three types of clicking:

       ClickRight - click the right button only

       ClickLeft - click the left button only

       ClickCenter - click the middle button.  On two button mice,
       click the left and right buttons together.

     3.2.2 Dragging

     The act of dragging is similar to clicking, except that the mouse
     is moved around while the buttons are held down.  A drag ends
     when the buttons are released.  In GC-PREVUE, dragging is used
     only in the graphical editor.  Dragging is used to move things
     around the screen, as if one had pressed one's fingers down on a

         8                 GC-PREVUE User's Guide
         _______________________________________________________

     piece of paper and dragged it around a desktop.  There are three
     types of drags:

       DragLeft - move the mouse while holding down the left button
       only.

       DragRight - move the mouse while holding down the right button
       only.

       DragCenter - move the mouse while holding down the middle
       button.  On two button mice, hold the left and right buttons
       together.

     Dragging can also be accomplished by holding down the appropriate
     mouse buttons while using the arrow keys.  This can be useful for
     precise shifting of data.

     3.3 Esc and Ctrl Break

     The Esc key always provides a way to leave from whatever GC-
     PREVUE action, area or menu you may be in.

     GC-PREVUE treats the Ctrl Break and Esc keys similarly, except
     that Ctrl Break works even when GC-PREVUE is not waiting for user
     input.  This makes it useful for interrupting screen reDraws and
     plotter data read and write operations.

     GC-PREVUE uses the Ctrl C key as a means of issuing a Command to
     DOS at any time (see Section 3.8).  We mention this here because
     some other programs use it as another BREAK key.

     3.4 Getting Help

     3.4.1 The Help Line

     The second line from the top of the GC-PREVUE screen (or the top
     line when in the graphical editor) always contains helpful
     information concerning the task at hand.  Help text is always
     colored yellow.

     3.4.2 ClickCenter or Ctrl M for Menu

     You can always review your current options by clicking the center
     button of the mouse, which causes a pop-up menu of commands to
     appear (see Section 3.5 to learn about menus).  If your hands
     happen to be on the keyboard, you can press Ctrl M to achieve the
     same effect.  You may select an action or ClickCenter/Ctrl M
     again to make the menu disappear.  Any command that can be
     performed from a menu can also be performed with a single
     keystroke.  Each entry in the pop-down menu has its single-key
     equivalent that is highlighted in yellow on color monitors or in
     brightened text on monochrome monitors.

         3: GC-PREVUE Basics                9
         _______________________________________________________

     These pop-up menus serve as a teaching guide to single-key
     commands.  As you begin to work faster, you will probably find
     yourself bypassing the menu system altogether, but it will always
     be there as a memory jogger.  The choice between using menus or
     keyboard commands is largely a matter of personal taste, so GC-
     PREVUE leaves it up to you.

     ClickCenter/Ctrl M will always give you a way out of whatever you
     are doing, either by featuring an Exit option in the pop-up menu
     or by simply acting as if you had pressed the Esc key.

     3.5 Using Menus

     3.5.1 Horizontal Menus

     A horizontal menu presents a list of choices across a single line
     of the screen.  Use the mouse or left and right arrow keys to
     position the cursor at the desired option.  ClickLeft or press
     Enter to select the currently highlighted option.  The main GC-
     PREVUE menu is an example of a horizontal menu.

     At the main menu, the Esc key causes GC-PREVUE to ask you if you
     want to quit the program altogether.  ClickCenter/Ctrl M serves
     the same purpose as the Esc key here, since all your options are
     already presented in the menu at hand.

     Note that each menu entry has one character highlighted in
     yellow.  Press the corresponding key for the same effect as if
     you had positioned the cursor on that menu entry then pressed
     Enter.

     3.5.2 Vertical Menus

     Most menus in GC-PREVUE have their entries arrayed vertically.
     Vertical menus work much like horizontal menus, except that the
     up and down arrow keys are used.  Each entry in a vertical menu
     indicates its single-key command equivalent by highlighting it in
     yellow.  There are two kinds of vertical menus:

       Pop Down menus, which appear as a result of actions at a
       horizontal menu.  Left and right movements take the cursor out
       of a pop down menu and on to the next horizontal menu entry.

       Pop Up menus, which appear as the result of actions other than
       those selected from a horizontal menu.  Pop Up menus differ
       from Pop Down menus in that once an action is selected from a
       Pop Up menu, the menu goes away.  To exit from a Pop Up menu
       either select an action, or press Esc or ClickCenter to escape
       with no action.

     3.6 Working with Data Input Windows

     A common sight in GC-PREVUE is a window containing a list of data
     fields for you to fill in.  Remember to watch the Help line for

         10                GC-PREVUE User's Guide
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     hints concerning the nature of the input required.  When you have
     everything the way you want it, press Enter or ClickLeft to
     proceed.  As ever, Esc cancels.

     3.6.1 Moving from Field to Field

     The Tab, Ctrl+arrow keys and the mouse both serve to move the
     cursor from one data field to the next.  The Ctrl+Home and
     Ctrl+End keys move to the extreme left and right respectively,
     while PgUp and PgDn move several lines up and down, respectively.
     To get to the top or bottom of a long list, press Ctrl PgUp or
     Ctrl PgDn.

     3.6.2 Editing a Data Field

     GC-PREVUE features a complete built in line editor.  To change an
     existing field, you can:

       Erase it completely by pressing Ctrl Backspace.

       Type over it, or press the Ins key to insert.  The cursor
       changes its shape to cover the entire character when in Insert
       mode.

       Use Del and Backspace to correct typing errors.

       Use Left or Right to move within the field.

       Use Ctrl Enter to see the effect of changes to the field
       without leaving the field.

     GC-PREVUE has special features to help with data fields that take
     filenames.  These features are described in Section 3.7.

     3.6.3 Toggles (Limited Choice Data Fields)

     Some fields have a limited range of values such as Yes/No or
     Inch/mm.  Such fields are called "Toggle" fields and are
     indicated by a special cursor that fills one-half of a
     character's height.  You can step through a toggle field's values
     using the Spacebar or ClickRight, or press F10 to see the entire
     range of choices.  You can also enter a value directly by
     pressing the first letter of the value desired.

     3.6.4 Units (Ctrl U)

     Anytime that you edit a data field that describes a distance or
     an offset, you can change between inch and millimeter units by
     pressing Ctrl U.

     3.6.5 Scrolling Large Lists

     Some lists are too long to fit inside a window all at once.  When
     this happens, an up or down arrow symbol appears in the left

         3: GC-PREVUE Basics                11
         _______________________________________________________

     column of the window to indicate that there are more data to be
     seen.  To get to these data, just keep pressing the up/down or
     PgUp/PgDn keys or use the mouse to move the cursor against the
     top or bottom of the visible list.

     3.6.6 Printing Lists (Alt P)

     You can always print a list to a disk file or printer by pressing
     Alt P, or by selecting "Print" from the ClickCenter pop-up menu.
     Send the list directly to the printer by specifying PRN as the
     output filename.  GC-PREVUE does not send a form feed.

     GC-PREVUE remembers the last-used filename for list printing and
     allows you to add subsequent printed lists to that file.  This
     provides a convenient way to maintain a written record of your
     work.

     Alt P prints complete lists of data that are too long to be
     listed on the screen of your computer at one time.

     3.7 Special Features for Filename Entries

     One special and frequently used type of data field is the
     filename.  A filename can include a complete drive and path
     designation if desired.  GC-PREVUE has two helpful features to
     speed your work with files, Interactive Directories and Default
     Filename Extensions.

     3.7.1 Interactive Directories

     Whenever GC-PREVUE asks for a filename, you can press F10 to
     select from a directory of files.  GC-PREVUE presents the most
     likely wildcard selection based on the type of file in question
     (for instance, *.PED for GC-PREVUE configuration files, or *.APR
     for aperture lists).  You can modify this if desired, then press
     Enter to see a list of files matching the wildcard description.
     The wildcard description can contain a complete path designation,
     referring to directories other than the current working
     directory.

     For long lists of files, you can move around the list in the
     usual up/down manner, or search for a file by typing up to eight
     letters of a filename.  The cursor moves to the right along the
     current line to indicate the number of search letters used.  The
     Backspace key resets the last search character.  Once the cursor
     is positioned on the name of the correct file, press Enter or
     ClickLeft to accept it.  As always, the Esc key gets you out
     without selecting anything.

     3.7.2 Default Filename Extensions

     When typing a filename directly, you can save a few keystrokes by
     letting GC-PREVUE attach the filename extension (that is, the

         12                GC-PREVUE User's Guide
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     ".ext" part of "filename.ext").  GC-PREVUE assumes the following
     filename extensions:

       .PED for configuration files
       .APR for aperture list files
       .PDF for plotter definition files
       .RCK for drill rack files
       .CAP for custom aperture files
       .PWK for GC-Prevue WorK files

     GC-PREVUE notes the last-used filename extension for plotter and
     NC data input files and treats it as the default.

     3.7.3 Hardware Devices as Output Files

     GC-PREVUE recognizes certain output filenames as DOS device
     names, including PRN, LPT1, LPT2, COM1 through COM4, and AUX.
     This allows direct output from GC-PREVUE to printers and
     plotters, although you must use the DOS "MODE" command to set up
     communication parameters.

     3.8 Perform a DOS Command (Ctrl C)

     One convenient feature of GC-PREVUE is the ability to execute any
     DOS command (subject to memory availability) from any part of GC-
     PREVUE, at any time, without leaving the program.  Just press
     Ctrl C and GC-PREVUE will ask you for a command to execute.  Once
     the command is completed, GC-PREVUE continues operating where you
     left off.

     GC-PREVUE presents "COMMAND.COM" as the default choice.  This
     command creates a new copy of DOS, which allows you to execute
     any series of commands (not just one command).  Use the EXIT
     command to return to GC-PREVUE (type EXIT at the DOS prompt after
     completing the commands).

         4: The GC-PREVUE Configuration             13
         _______________________________________________________

     4.
     GC-PREVUE Configuration
     _________________________________________________________________


     GC-PREVUE provides a means of saving its setup information for
     later use.  In addition to the items shown in the "Configuration"
     area at the bottom of the main GC-PREVUE screen, GC-PREVUE saves
     information such as aperture list selections, drill rack
     selection, input data format, graphics display type, and more.

     4.1 Load a Configuration

     At startup, GC-PREVUE will automatically load the configuration
     found in file "DEFAULT.PED".  This is generally the easiest way
     to use configuration files - set GC-PREVUE up the way you like
     it, then save the configuration to "DEFAULT.PED".  An alternative
     way to use configuration files is on the DOS command line.  In
     order to start GC-PREVUE with the configuration found in
     "MYCONFIG.PED", you could type:

       GCPREVUE  /MYCONFIG

     To load a configuration from inside GC-PREVUE, select the
     "Configure" option on the main GC-PREVUE menu.  This produces a
     pop down menu from which you can select "Load Configuration".
     GC-PREVUE will prompt you for a filename.

     Aperture Lists and the Drill Rack are automatically loaded as
     part of the configuration loading process.

     4.2 Save the Configuration

     To save the current GC-PREVUE configuration, select "Save
     Configuration" from the "Configure" pop down menu.  GC-PREVUE
     will prompt you for a filename.  If you want this configuration
     to be loaded automatically at the next start of GC-PREVUE, name
     the output file "DEFAULT.PED".

         14                GC-PREVUE User's Guide
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            Figure 4.1: Configuration File Input Window

     4.3 Bed Size

     When in the GC-PREVUE graphical Viewer, you will notice a dark
     grey rectangle (adjust your monitor if you don't see it) which
     represents the extents of the useful plotting area.  You can set
     these extents using the "Bed Size" entry of the "Configure" pull-
     down menu.  You can also access this from inside the GC-PREVUE
     Viewer.

     4.4 Reminder Interval

     To help prevent you from losing work due to power outages and
     other mishaps, GC-PREVUE can periodically remind you to save your
     work to a PWK (Prevue WorK) file.  In the Configuration pull-down
     menu, select "Reminder Interval" (I).  Choose the time between
     reminders by typing in a specific number of minutes.  If you
     would rather not be reminded to save, select "0".

     4.5 Graphics Display Type

     Here you can tell GC-PREVUE what kind of graphics display system
     you use.  GC-PREVUE supports the most popular graphics display
     types (Hercules, CGA, EGA, VGA, SuperVGA), and can recognize them
     automatically when "Autosense Graphics" is selected.  Of course
     you can also select a specific graphics type, which is useful for
     "clone" machines which may not behave according to standard,
     making identification difficult.  AutoSense will detect Hercules,
     CGA, EGA and VGA adapters.  If you have SuperVGA, you must select
     it explicitly since there are several competing "standards" for
     SuperVGA graphics.

     GC-PREVUE supports SuperVGA adapters in 800x600 16 color mode.
     Select Graphics Display Type from the Configure menu to see a
     list of supported SuperVGA adapters.  If your adapter's brand

         4: The GC-PREVUE Configuration             15
         _______________________________________________________

     name is not in the list, try Tseng or Chips & Technologies.
     These are not adapter brands but rather brands of BIOS chips
     built into many popular SuperVGA adapters.

     For Hi Res graphics (1024x786), GC-PREVUE supports Video 7 and
     its emulators only.

     If GC-PREVUE thinks that the requested and detected display types
     do not match, a warning will be issued but the request will be
     granted.  EGA displays can safely do CGA graphics, and VGA can do
     EGA or CGA graphics, however:

       NOTE THAT THERE IS SOME POSSIBILITY OF DAMAGE TO YOUR SYSTEM IF
       YOU SELECT A DISPLAY TYPE OTHER THAN THAT WHICH IS ACTUALLY
       INSTALLED!

     4.6 Beep

     The GC-PREVUE warning tone toggles on and off each time Beep is
     selected.  This feature is provided simply for the convenience of
     those who prefer a quiet work place.

     4.7 Mouse Sensitivity

     Use this entry to set the responsiveness of your mouse.
     ClickRight decreases sensitivity (longer mouse moves), and
     ClickLeft increases sensitivity.  When your mouse moves at an
     acceptable speed, press Enter.

         5: Aperture Lists                  16
         _______________________________________________________

     5.
     Aperture Lists
     _________________________________________________________________


     Each of the 35 layers can be associated with any one of up to 10
     aperture lists via the "Aps" field of the Layer List.  To change
     any of the aperture lists themselves, select "Apertures" from the
     main menu.  The Aperture Lists selections are saved as part of
     the system configuration, and are loaded automatically when a
     configuration is loaded.  GC-PREVUE is also capable of generating
     an aperture list from Gerber file data (see Section 7.1.3).

     This section is divided into 2 parts.  The first part (Section
     5.1) describes the GC-PREVUE features for working with apertures.
     The second part (Section 5.2) explains how you access these
     features and put them to work.

     5.1 Special Aperture List Features

     GC-PREVUE aperture lists contain, as you would expect,
     information about each aperture's shape, size and selection ("D")
     code.  In addition, GC-PREVUE aperture lists contain information
     regarding drill/router use and data rotation.  In this section we
     describe each field of an aperture description.

     5.1.1 Aperture Position

     Because a GC-PREVUE aperture contains so much more information
     than just its "D" code, an aperture is referred to by aperture
     position rather than by "D" code.

     5.1.2 Aperture Code

     This is the "D" code used in Gerber data to select an aperture.
     This information is needed for reading Gerber-format data.

     5.1.3 Drill

     Any one of the up to 254 drills/router bits in the drill rack may
     be associated with each aperture.  A value of 0 here indicates
     that the aperture is not associated with any drill or router
     information.  This information is of use only to the Copy NC
     function, which lets you visualize a drill layer created from a
     photoplot layer (see section 7.3.7).

     5.1.4 Rotate +/-90 (R90)

     Rotating data is not as simple as it may seem at first.  If your
     data uses apertures such as ovals and rectangles, which are not
     symmetrical in rotation, then a rotation of +/- 90 degrees could
     result in an erroneous plot.  This is because pad locations
     rotate but the pads themselves do not, since the shape and
     orientation of an aperture is fixed.

         5: Aperture Lists                  17
         _______________________________________________________

     GC-PREVUE helps solve this problem by allowing you to specify a
     substitute aperture position to be used in such rotations.  GC-
     PREVUE will automatically search for a suitable match whenever
     you describe an aperture which is not symmetrical.  Note that
     this has no effect on Draw-type apertures, which are assumed to
     be round, or on non-Draw apertures used for drawing.

     5.1.5 Dimensions

     For symmetrical shapes, the dimension is read as a diameter.  For
     non-symmetric shapes, the first (major) and second (minor)
     dimensions are read as X and Y widths respectively.  For shapes
     such as Annuals and Thermal, the dimensions represent Inner and
     Outer diameters.  The "Target" shape is described by diameter and
     line weight.

     For custom apertures, the Dimension information is replaced by
     the name of the file containing the custom aperture description
     (see Appendix A).  Once the filename is typed in, the F1 key
     loads the custom aperture description in that file.  The
     description becomes a permanent part of the aperture list when
     the list is saved to an APR disk file.

     5.1.6 Aperture Type

     GC-PREVUE supports the most popular standard pad shapes as well
     as custom aperture shapes.  Standard shapes include: round;
     octagon; square; rectangle; oval; annulus; slit; and a stylized
     thermal relief and target.  The APER program included with GC-
     PREVUE allows you to define custom apertures for true WYSIWYG
     viewing and plotting (see Appendix A).  Custom apertures are kept
     in special-format files and are loaded into an aperture list by
     filename reference.

     GC-PREVUE supports the drawing of traces with rectangular
     apertures.  A "Draw"-type aperture is assumed to be round.  If a
     non-"Draw", non-rectangular aperture is used for drawing, it is
     assumed for display purposes to be round and of the diameter
     given in the major dimension.  Attempting to draw a trace with a
     custom aperture will have unpredictable results.

     5.1.7 Invisible Apertures

     Sometimes it is convenient to disable the display of data
     associated with certain positions in an aperture list.  Disabled
     apertures are referred to as "Invisible".  Any aperture can be
     made Invisible.  Data associated with Invisible apertures;, like
     invisible drills, do not display.  An Invisible aperture is
     marked by an asterisk ("*") next to its Type description.  An
     Aperture List containing invisible apertures has an asterisk next
     to its name in the "Aperture Lists" area of the main GC-PREVUE
     screen, and any layers using an Aperture List containing
     Invisible apertures will have an asterisk next to their entry in
     the Setup Status area of the graphical Viewer screen.

         18                GC-PREVUE User's Guide
         _______________________________________________________

     The invisibility attribute of an aperture can be changed from
     within the graphical Viewer, making it a useful analysis tool.

     5.2 Working with Aperture Lists

     To begin working with Aperture Lists, you must select "Apertures"
     from the main menu.  Once in the Aperture Lists area, press Ctrl
     M or ClickCenter for a menu of options as described below.  The
     chosen action applies to the Aperture list currently highlighted
     by the cursor.

     5.2.1 Load/Create an Aperture List (F1)

     To load an Aperture List from disk, just type the name of the
     file, or press F10 to select one or more filenames from a
     directory.  Once the filename is correct, press F1 to load the
     file.

     If the filename is empty, GC-PREVUE will offer to create a new
     aperture list.  GC-PREVUE asks how many positions will be on the
     new list, then creates it for you and presents it for editing.
     For lists of 24 or fewer positions, the default D code numbering
     scheme is that which is used by traditional vector photoplotters.
     Be sure to fill in all the dimensions and set the Types
     correctly.  A more convenient way to create an aperture list is
     to generate it from the plotter data (see Section 7.1.3).

     5.2.2 Unload an Aperture List (Ctrl F1)

     If you are not using a loaded Aperture List, you can save some
     memory by removing it from the list of Aperture Lists.  If the
     Aperture List has been edited, GC-PREVUE will give you a chance
     to save it before erasing it.

     5.2.3 Edit an Aperture List (F2)

     F2 pops up a window containing the currently selected aperture
     list's aperture information.  This information can be edited.

         5: Aperture Lists                  19
         _______________________________________________________



















               Figure 5.1: Aperture List Edit Screen

     To change any numeric value, just position the cursor on the
     appropriate field and type in the new value.  Use ClickCenter to
     see the menu of commands for editing an aperture list, which
     include the ability to:

       Add a position (Ctrl A)
       Remove a position (Ctrl R)
       Make a position "Invisible" (Ctrl I)
       Jump to a position (Ctrl J)
       Sort the aperture list on ascending D codes (Ctrl S)
       Sort the aperture list "Gerber Style" (Alt S)
       Automatically rotate asymmetric pads (Alt R)
       Set the units for dimensions (Ctrl U)

     The Shift key used in conjunction with function keys F1 through
     F12 set the aperture Type as indicated by an on-screen help
     display.  If your keyboard does not have an F11 or F12 function
     key, press Alt F1 or Alt F2 instead. Review Section 5.1 for the
     meaning of each field in an aperture list.  Press F10 to pop up a
     copy of the current drill rack for inspection.

     IMPORTANT: Editing an Aperture List after it has been used to
     load photoplot data will lead to unpredictable results,
     particularly if positions are removed.  Any layers that use such
     a list should be reloaded.

     5.2.4 Inspect an Aperture List (F3)

     To view an aperture list's contents without changing them,
     position the cursor on the list in question then press F3.  You
     may also inspect an aperture list while you are checking data on
     the View screen by pressing F10.

         20                GC-PREVUE User's Guide
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     5.2.5 Write an Aperture List to Disk (F4)

     Once you have set up an Aperture List to your satisfaction, you
     will want to save it for future use.  It's best to save
     immediately using this option.  However, GC-PREVUE will make sure
     you get a chance to save an edited Aperture List before leaving
     the program or loading a new Aperture List in its place.

     5.2.6 Copy & Resize an Aperture List (F5)

     Sometimes it is convenient to have a copy of an aperture list
     with slightly larger or smaller dimensions for each aperture, for
     making a silkscreen or perhaps a ground plane isolation.  When
     copying the currently selected aperture list to the first
     available Aperture List table slot, GC-PREVUE lets you add or
     subtract a given amount from the radius of each copied aperture.

     If the aperture list being copied contains custom apertures, GC-
     PREVUE will copy and adjust those too, then ask for new filenames
     for saving the new custom apertures.  It is not strictly
     necessary to save these new custom apertures to individual files
     (they will be preserved by saving the new aperture list itself),
     so you can just ESCape out of the filename prompt.

         6: The Drill Rack                  21
         _______________________________________________________

     6.
     The Drill Rack
     _________________________________________________________________


     The Drill Rack is a list of up to 254 drill selection codes and
     diameters used when reading, writing, creating and especially
     viewing/editing NC Drill data layers.  The diameter information
     allows drill locations to be displayed at width.  All layers and
     all Aperture Lists refer to the same single Drill Rack.

     The current Drill Rack selection is displayed in the
     "Configuration" area at the bottom of the main GC-PREVUE screen.

     You can use GC-PREVUE's Aperture List editor to associate each
     aperture in an Aperture List with any one (or none) of the drills
     in the Drill Rack.  This information is used by the "Copy NC"
     function in the GC-PREVUE Layer List to create NC drill data
     layers from photoplot data layers.

     You may inspect the Drill Rack while in the Aperture List editor,
     and you may inspect the Drill Rack or any Aperture List while in
     the Viewer.

     6.1 Special Drill Rack Features

     6.1.1 Diameter

     To change the display diameter of a drill, just position the
     cursor on that drill's diameter value and type in a new value.
     Press Ctrl U to change units.

     6.1.2 Invisible Drills

     Sometimes it is convenient to disable the display of data
     associated with certain positions in the Drill Rack.  Data which
     use  invisible drills do not display or write.  If the Drill Rack
     contains Invisible entries, an asterisk ("*") appears by the
     "Drill Rack" entry in the Configuration display area of the main
     GC-PREVUE screen.  In the graphical Viewer, an asterisk appears
     next to the Setup Status entry for each layer using the Drill
     Rack if the Drill Rack contains invisible drills.

     The Invisibility attribute of a drill can also be changed from
     within the graphical data Viewer, making it a useful analysis
     tool.

     6.2 Working with the Drill Rack

     When you select the "Drills" option from the GC-PREVUE main menu,
     a menu appears allowing you to variously create, edit, save and
     recall Drill Racks.  The menu selections are as follows:

         22                GC-PREVUE User's Guide
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     6.2.1 Load a Drill Rack

     When "Load" is selected from the Drills menu, GC-PREVUE offers to
     save the current Drill Rack if it has been edited.  GC-PREVUE
     then prompts for a filename for loading the next Drill rack.

     6.2.2 Save the Drill Rack

     When "Save" is selected from the Drills menu, GC-PREVUE prompts
     for a filename for saving the current Drill Rack to disk.

     6.2.3 Edit the Drill Rack

     When "Edit" is selected from the Drills menu, GC-PREVUE pops up a
     copy of the current Drill Rack for inspection and editing.  To
     change a value, just position the cursor on the value and type in
     a new value.  As usual, ClickCenter or Ctrl M present a menu of
     commands, as described below:

     Add and Remove Drills

     GC-PREVUE allows you to change the number of entries in a Drill
     Rack.  Ctrl A and Ctrl R Add and Remove drills respectively.  GC-
     PREVUE will ask you to verify the action before deleting a drill.

     Make a Drill Invisible

     Pressing Ctrl I toggles the Invisibility of the currently
     selected drill.

     Set Units

     Pressing Ctrl U sets the drill rack display units to inch, mm or
     mil.

     6.2.4 Make a New Drill Rack

     When "New" is selected from the Drills menu GC-PREVUE offers to
     save the current Drill Rack if it has been edited, then prompts
     for the number of positions in the new rack.  GC-PREVUE then
     brings up the new rack for editing.

     Drill Racks can also be created "on the fly", based on the T
     codes found while reading NC drill data files (see Section
     7.1.3).  Such racks still require editing to set tool diameters.

         7: Working with Plotter and NC Data        23
         _______________________________________________________

     7.
     Working with Plotter and
     NC Data
     _________________________________________________________________


     This section covers the essentials of reading and manipulating
     photoplotter, HPGL, NC drill/rout data.  Section 8 covers viewing
     the data in greater detail.

     7.1 The Layer List

     The Layer List takes up most of the main GC-PREVUE screen, and is
     where the majority of your work is done.  Up to 35 layers can be
     in the list.  To get to the Layer List, select the "Layers" entry
     from the main (horizontal) menu.  Note that not all 35 layers fit
     on-screen at once - just scroll the list using the up/down keys.
     In this section we'll explain each of the columns in a Layer List
     entry.

     7.1.1 Status: Empty or Loaded

     This field indicates the presence and status of data on a layer.
     "Empty" indicates that the layer is unused.  When the status is
     "Loaded", data file has been read in to this layer.

     7.1.2 Offset(inch/mm) X,Y

     The "Offset(inch/mm)" entries indicate the offset to be applied
     to each layer for display and output purposes.  Such shifting can
     be achieved either by typing in the offsets directly at the
     appropriate field in the Layer List, or by entering the Viewer
     and using Offset.

     The shift values are displayed in inch or metric units depending
     on the last units used in the Viewer or while loading data.  The
     Ctrl U key changes the display from inch to metric and back
     again.

     7.1.3 Aperture List ("Aps")

     Each layer must be associated with any one of the up to ten
     different Aperture Lists, or with the Drill Rack if the layer
     contains NC drill/rout data.  An Aperture List is referred to by
     the letter (A through J), which appears next to its name in the
     "Aperture Lists" table just below the Layer List area of the main
     GC-PREVUE screen.  The Drill Rack is denoted by the letter "T".

     Automatic Generation of
     Aperture Lists and Drill Racks

     If the "Aps" selection for a layer refers to an empty Drill Rack
     or Aperture List entry, GC-PREVUE will offer to create an
     Aperture List or Drill Rack based on the input data file for that

         24                GC-PREVUE User's Guide
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     layer.  When the layer is loaded (as described in Section 7.3.1),
     GC-PREVUE will confirm that the Aperture List or Drill Rack is
     intentionally blank and then will construct a list containing the
     aperture or drill selection codes found.  Dimensions will be
     zeroed, meaning that you must edit the new Aperture List or Drill
     Rack to assign dimensions (see Section 5.2.3 for aperture
     editing, and Section 6.2.3 for Drill Rack editing).

     Additionally, if GC-PREVUE encounters an unknown tool code while
     reading a file using an existing Aperture List or Drill Rack, GC-
     PREVUE will offer to append the new code to the Aperture List or
     Drill Rack in use.  Again the new aperture or drill will have a
     diameter of zero and must be edited to view properly.

     You can edit the aperture list or drill rack by placing the
     cursor in the "Aps" column and pressing F10.

     7.1.4 Layer Polarity

     Many raster devices (including PostScript checkplots) support
     both positive and negative data polarity.  By using combinations
     of positive and negative data layers, many effects (such as
     ground plane isolation) that traditionally required tedious
     photo-mechanical techniques can now be produced on first-
     generation film.

     GC-PREVUE can display negative layers in the normal selected
     display color, or in black for true WYSIWYG viewing.  Polarity
     for each layer is displayed and changeable in the layer list,
     just to right of the aperture list selection:

       "+" symbol for positive (draw) layers
       "-" symbol for negative (inverse video) layers
       "c" symbol for composite (undraw) layers

     A "Positive" layer assumes that all pixels are initially off, and
     turns pixels on to create features.

     A "Negative" layer assumes that all pixels are initially on, and
     turns pixels off to create features.  When Control Draw (Ctrl D)
     has been used to set "Negative Layers Draw In: Black", a Negative
     layer first fills the film extents with its assigned layer color,
     then draws on top of this in black.

     A "Composite" layer makes no assumptions about initial pixel
     values, but turns pixels off to create features.  When Control
     Draw (Ctrl D) has been used to set "Negative Layers Draw In:
     Black", a Composite layer draws in black but, unlike a "Negative"
     layer, does not first fill the bed extents.

     7.1.5 Filename

     Most layers are associated with a disk file of plotter or NC
     data, although data layers can be created in the Viewer or by

         7: Working with Plotter and NC Data        25
         _______________________________________________________

     using the Copy and Copy NC functions.  You can change the
     filename for a layer at any time, but the filename must be that
     of a real file when you go to load a layer from disk (see the
     following example).

     To enter or change a filename, just position the cursor in the
     Filename column and type in a new name.  To enter one or more
     filenames selected from a directory, do the following:

       Position the cursor in the Filename column of the first layer
       which is to receive a filename and press F10.

       A wildcard entry window pops up.  The default wildcards show
       the last used filename extension (for example, "*.GBR").  You
       can change the wildcards to match any set of files in any
       directory (consult your DOS manual for more information on
       wildcards and paths).

       Press Enter to pop up a list of filenames that match the
       wildcard selection.

       Select files from the list by positioning the cursor on each
       desired filename, followed by ClickRight or the Spacebar.
       Selected filenames are displayed in inverse video (black on
       white).  Cancel file selections by repeating the ClickRight or
       Spacebar action.  To find a filename in a long list of
       filenames, type in the first few letters of the desired name.
       The BackSpace key lets you change the search letters.

       ClickLeft or press Enter to copy all the selected filenames to
       the Layer List.

     EXAMPLE  For a job that consists of the 3 layers "DEMODAT1.GBR",
     "DEMODAT2.GBR", and "DEMODAT3.NC", begin by positioning the
     cursor on the first unused line of the Layer List, then press
     F10.  Set the wildcard window to read "DEMODAT?.*", and press
     Enter.  The list of matched files pops up.  Select the desired
     files from the list and press Enter again.  Since DEMODAT3.NC
     contains drill information, the "Aps" aperture list selection for
     that layer should be set to "T", meaning that it uses the Drill
     Rack directly.  The layers can now be loaded using F1.

     7.2 Loading Layers from Data Files

     The Load (F1) option from the Layer List menu lets you load
     layers from the disk files indicated in the Filename column.

     To load a data file, type in its filename at the layer list then
     press F1.  GC-PREVUE pops up a menu from which you can select one
     of several different input data formats, including:

         26                GC-PREVUE User's Guide
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       Gerber (RS-274-D)
       NC Drill
       NC Rout
       HPGL
       Quest (Marconi Emma)
       AUTO (GC-PREVUE figures out the file formats automatically)

     The use of each of these input formats is explained in the
     following sections.

     GC-PREVUE can generate or add to Drill Racks and Aperture Lists
     while reading input data files (see Section 7.1.3).  Drill Racks
     and Aperture Lists created or expanded in this manner require
     editing to set tool diameters for display.

     7.2.1 Gerber, NC Drill and NC Rout Files

     Gerber (RS-274-D) and NC data files have very similar formats, so
     we'll treat them here in a single section.  The main difference
     is that Gerber files are read using an aperture list while NC
     files are read using the Drill Rack.

     Gerber and NC data files tend to appear in dialect, which is to
     say that they adhere to format standards rather loosely.  For
     this reason, GC-PREVUE asks you to specify a plotter definition
     file (PDF) and lets you change various PDF input parameter
     settings before attempting to read a file.  Once the data files
     have been read, GC-PREVUE gives you a chance to save any PDF
     changes for future use.

     GC-PREVUE presents an input window containing the fields
     described below.  Most of the fields describe aspects of the
     input data format.  (If you are unfamiliar with the terms, see
     Section 7.1).



















           Figure 7.1: GC-PREVUE Loading Format Options

         7: Working with Plotter and NC Data        27
         _______________________________________________________

     Layers

     Any or all layers can be specified for loading.  Note that if
     multiple layers are to be loaded at once, they must use identical
     data formats.  Layers are specified by number.  Acceptable
     specifications include:

       all
       3
       1,2,4,6
       1-7
       not 4,8

     Error File

     Typical errors while reading a file include misuse of flash/draw
     apertures and use of apertures not declared in the aperture list.
     To log such errors to a file in addition to displaying them on-
     screen, provide a filename here.

     Plotter

     Enter the name of a previously created plotter definition file
     (PDF), or leave this field blank and fill in the following fields
     manually.  You can also specify a PDF here then modify it by
     changing the following fields.  GC-PREVUE lets you save any
     modifications after the data are loaded.

     Whole Digits

     This field specifies the input format in terms of the number of
     digits to be read as whole units.

     Precision

     This field specifies the input format in terms of the number of
     digits to be read as fractional units.

     Absolute/Incremental

     This field specifies absolute or relative input data.  This
     setting may be overridden by codes in the data file.

     Zero Suppression

     Choose from "Leading," "Trailing" or "None."  Leading zero
     suppression is the most common.

     Units

     This field specifies inch or metric (mm) input data.  This
     setting may be overridden by codes in the data file.

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     Coordinate System

     This selects the coordinate system for loading the data.  Choose
     Absolute or User Coordinates.  If User Coordinates are selected,
     data will be loaded using the User Coordinate system origin.

     Arc Style

     Select either "Quadrant" or "Full 360."  Most photoplotters and
     NC machines use only Quadrant arc styles, which allow for
     positive-only I and J codes.  You can toggle to Full 360 if the
     data are intended for a plotter with Full 360 degree (signed I
     and J) arc data recognition.

     This entry is useful for NC Drill input files, since drill files
     may also contain rout information, and vice versa.

     Flash/Draw Check (Gerber only)

     GC-PREVUE will warn you of the cross-use of apertures (Flash with
     Draw-type aperture, or vice versa) if the Flash/Draw check is set
     to "Yes".  This is primarily of use on older vector plotters.
     Set Flash/Draw check to "No" if your target plotter is a laser
     plotter or some other raster device.

     Modal Tool Peck (Gerber only)

     On most photoplotters, a Flash occurs only when a data block
     contains a D03 code.  This is the Modal Tool Peck "No" case, and
     is standard for photoplotters.  Some plotters depart from the
     standard and flash at each block after a D03 code until a D02 or
     D01 comes along, whether each block contains a D03 or not.  This
     is the Modal Tool Peck "Yes" case.

     Character Set

     GC-PREVUE can read and write ASCII, EIA, or EBCDIC data.  ASCII
     is by far the most commonly used character set, while EBCDIC is
     common in files downloaded from IBM mainframe computers.  Many NC
     drill and rout machines read EIA data.

     Magtape Filter (Gerber only)

     Enabling the Magtape Filter causes GC-PREVUE to ignore carriage
     returns, linefeeds, nulls and spaces when reading Gerber data.
     This is useful for data files that have been received from
     mainframes or other workstations that insert padding characters
     and new lines at regular intervals (sometimes in the middle of a
     data value).

     X and Y Offsets

     These fields allow you to read data for devices with fixed
     coordinates systems, which differ from the selected coordinate

         7: Working with Plotter and NC Data        29
         _______________________________________________________

     system.  Any X or Y offset given will be added to all coordinates
     read.  This feature works independent of the selected coordinate
     system.

     7.2.2 HPGL Files

     HPGL files can be loaded on layers using either the Drill rack or
     an aperture list.  Pen 1 corresponds to position 1 of the
     aperture list or drill rack, pen 2 to position 2, and so forth.
     The entire HPGL instruction set is implemented, including
     polygons.  Polygons are scan-converted to vectors (filled) as
     they are loaded.

     Layers

     Any or all layers can be specified for loading.  Note that if
     multiple layers are to be loaded at once, they must use identical
     data formats.  Layers are specified by number.

     Error File

     To log any data errors to a file in addition to displaying them
     on-screen, provide a filename here.

     Plotter

     Proper interpretation of HPGL depends heavily on certain scaling
     parameters.  Many CAD programs fail to include these in their
     output HPGL data, depending instead on the default scaling
     parameters for the target plotter.  GC-PREVUE can achieve the
     proper scaling if it knows the plotter model and paper size for
     which the data were intended.  Press F10 to select from a list of
     plotters and paper sizes.  Selections marked "EXPAND" assume that
     the EXPAND hardware feature for this plotter is Yes.

     If your HPGL data files include IP and SC commands, the Plotter
     selection is unimportant since these commands override the
     default scaling.

     Ignore chord tolerances

     GC-PREVUE can load HPGL arc information two different ways: as
     true arcs or as connected line segments (vectorized arcs).  When
     "Ignore chord tolerances" is "Yes," arcs are stored as true arcs
     (endpoints and arc center).  When "Ignore chord tolerances" is
     "No", GC-PREVUE converts arcs to vectors based on the HPGL CT
     (Chord Tolerance) command, or to a default of one vector per 5
     degrees of arc.

     Fill Adjust

     When reading HPGL polygon information, GC-PREVUE can compensate
     for tool width so that polygons fill exactly to the programmed
     dimensions.  This is done by shrinking the programmed polygon

         30                GC-PREVUE User's Guide
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     edges in by one tool radius, which is the Fill Adjust "Yes"
     state.  When Fill Adjust is "No", polygons will be filled based
     on the programmed centerlines of the polygon edges, which results
     in a polygon whose actual dimensions are one tool radius greater
     than programmed.

     Units Adjust

     A surprisingly common error in CAD output data is the assumption
     that one HPGL unit is equal to .001 inch.  This is not true!  HP
     defines the HPGL unit as follows:

     1 HPGL unit     =    0.025 mm (0.0098425 inches)
     40 HPGL units       =    1.0 mm
     1016 HPGL units     =    1.0 inch

     By setting Units Adjust to "Yes", you tell GC-PREVUE to correct
     for this scaling error when reading HPGL data.

     7.2.3 Quest Files

     Quest files (or Marconi Emma, as they are sometimes known) can be
     loaded on layers using either the Drill rack or an aperture list.
     Slide I0 corresponds to position 1 of the aperture list or drill
     rack, slide I1 to position 2, and so forth.

     Layers

     Any or all layers can be specified for loading.  Note that if
     multiple layers are to be loaded at once, they must use identical
     data formats.  Layers are specified by number.

     Error File

     To log any data errors to a file in addition to displaying them
     on-screen, provide a filename here.

     Units

     This field specifies inch or metric(mm) input data.

     Character Set

     GC-PREVUE can read and write ASCII, EIA or EBCDIC data.  ASCII is
     by far the most commonly used character set, while EBCDIC is
     common in files downloaded from IBM mainframe computers.  Many NC
     drill and rout machines read EIA data.

     7.2.4 Automatic File Format Detection

     If you don't know a file's data format, GC-PREVUE can figure it
     out for you.  Just select Auto and GC-PREVUE asks for a list of
     layers to load (they don't all have to use the same data format)
     and an optional error log filename.

         7: Working with Plotter and NC Data        31
         _______________________________________________________

     7.3 Working with the Layer List

     Most of the action in GC-PREVUE centers on the Layer List area,
     including reading, writing, editing and copying data layers.



















                Figure 7.2: Layer List Menu

     7.3.1 Load (F1)

     This function provides for loading layers from disk data files of
     various formats.  See Section 7.2 for specific information on
     using each of these input formats.

     7.3.2 Unload Layers (Ctrl F1)

     Unloading a layer means erasing all data on the layer.  GC-PREVUE
     will ask you to confirm this action, since once data is erased it
     cannot be recovered except by re-reading a data file, and any
     manipulation is lost permanently unless it has saved (F6).

     7.3.3 View Layer(s) (F2)

     F2 takes you to GC-PREVUE's multi-layer graphical data Viewer,
     which is described in detail in Section 8.

     7.3.4 Layer Report (F3)

     F3 produces a description of the current layer.  This report
     includes:

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       Layer's data extents
       Aperture list (or drill rack) used
       Pad and trace counts by aperture
       Sample X,Y location for each aperture used
       Total pad and trace count

     The data extents take the dimensions of apertures and drills into
     account.

     7.3.5 CheckPlot (Alt F4)

     This feature enables you to output data to HPGL penplotters or to
     printers that support Postscript, with user-defined scale.  Press
     Alt F4 to pop up menu of CheckPlot controls, which are:

       Output file: select the output filename (press F10 for a list
       of possible names).

       Layers: specify layer(s) that you wish to CheckPlot.

       Plotter: choose either Postscript or one of the many HP
       plotters, which may be displayed on a list by pressing F10.

       Style: pick from the output drawing styles of Normal,
       Transparent, and Ball & Stick.

       Pen Width: type in pen width for filled penplots and unfilled
       Postscript output.

       Edge Adjust: select "Yes" to adjust pen thickness on polygon
       fills (reducing fill by one pen width).  "No" fills following
       the center line instructions.

       X Y Scaling: Establish the scale of the output relative to the
       data.

       Pads: output pads by turning "Yes."

       Traces: output traces by turning "Yes."

     7.3.6 Copy Layers (F5)

     "Copy" copies data from one or more layers to a single target
     layer.  If the target layer is not empty, GC-PREVUE offers to
     clear it first, otherwise the copied data is appended to the
     existing data.  The new layer uses the filename of the source
     layer, substitutes the filename extension ".CPY", then encloses
     the new filename in parenthesis.  Layers are copied with their XY
     offsets added in.

     A layer cannot be copied to itself.  Mixing layers which use
     different Aperture Lists will have unpredictable results.

         7: Working with Plotter and NC Data        33
         _______________________________________________________

     7.3.7 Copy NC (Ctrl F5)

     The Copy NC function is provided to allow quick and easy
     generation of NC drill and router information from photoplot pad
     and trace data.  (Note: It will not generate NC information from
     HPGL data.)

     This powerful GC-PREVUE function behaves like Copy (F5) except
     that the target layer is automatically set to use the Drill Rack
     (the "Aps" selection is set to "T" to indicate the presence of NC
     data).  The aperture selection for each copied pad or trace is
     translated to a drill selection, based on the T code translation
     values found in the source layer's Aperture List.  The new layer
     uses the copied layer's filename except that it replaces the
     filename's extension with ".NC" and encloses the new filename in
     parenthesis.

     Pads and traces using aperture positions with a T code
     translation value of zero do not copy.

     Mixing layers that use different Aperture Lists is quite
     acceptable, since all layers use the same Drill Rack.

     7.3.8 Save All Work (F6)

     This feature, which also appears in the graphical Viewer, allows
     you to quickly save the work in progress on all layers to a
     single PWK (gc-Prevue WorK) disk file.  It is a good idea to save
     your work often, since you never know when power failures or
     other disasters might come along.

     A PWK file contains all your layer data, aperture lists, custom
     apertures, and drill rack information.  As such, it represents a
     complete representation of your job and is a convenient way to
     communicate with your plotting service or board house if they
     also have GC-PREVUE or a higher level GraphiCode software
     product.

     7.3.9 Restore All Work (F7)

     This feature allows you to restore work saved using "Save All"
     (F6).  This can be a lifesaver, but it can't work if you don't
     use Save All first!

     7.3.10 Move Layer to Top of List (F8)

     This moves the current layer to the top of the list (layer 1).
     In the Viewer, the top (lowest-numbered) layer is the last to
     draw and it overwrites any layers that may be below it.

     It is generally convenient to place NC data layers at the top of
     the layer list so that drill positions can be viewed when the
     Viewer is in its normal (non-transparent) drawing mode.  You may
     also reorder the layers inside the Viewer.

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     7.3.11 Set Layer Color (F9)

     This option sets the color for displaying a layer.  GC-PREVUE
     pops up a window containing the available colors.  Select a color
     by positioning the cursor on the bar with the desired color and
     pressing Enter, or press the indicated key to quick-select a
     color.  You may also set color within the Viewer.

     7.3.12 Set... (Ctrl S)

     This feature lets you set various layer attributes for more than
     one layer at a time, such as color, hide/View, and data polarity.
     GC-PREVUE pops up a window asking for a list of layers to be
     changed, and lets you set various layer attributes to "No Change"
     or the desired new value for all the listed layers.

     7.3.13 Set Display Units (Ctrl U)

     This sets the units for displaying the X and Y layer offsets.

     7.3.14 Print Layer List (Alt P)

     In addition to the contents of the Layer List, Alt P prints the
     current Aperture List and Drill Rack filename selections.  This
     provides a complete record of the current job status.

         8: Viewing Data                    35
         _______________________________________________________

     8.
     View Data
     _________________________________________________________________


     The GC-PREVUE Viewer provides for the graphical manipulation of
     pads and traces of data layers.

     8.1 The Viewer Display

     The GC-PREVUE Viewer display consists of two principal areas: The
     larger area being the data display area; and the smaller being
     the help/status/setup area along the top and right of the screen.
     The data cursor, a white crosshair, stays in the data area unless
     it is directed the Setup area.  Place the cursor in the Setup
     area by pressing the S key or simply by moving the data cursor to
     the far right of the screen.  Press Esc or move cursor with mouse
     or arrow keys to re-enter the data display.





















            Figure 8.1: GC-PREVUE Viewer Screen

     8.1.1 The Help Line

     The top line of the screen displays helpful messages concerning
     the state of the Viewer and hints concerning data entry.

     8.1.2 Absolute X,Y

     This gives the current data cursor position in absolute plotter
     bed coordinates.

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     8.1.3 Relative X,Y

     This gives the current data cursor position in coordinates
     relative to the last position at which the Relative display was
     zeroed (via pop-up menu or the Z key).  This is useful for
     measuring.

     8.1.4 Grids: Step, Snap, & Show

     The GC-PREVUE data cursor moves on a user-defined grid.  The Step
     Grid display indicates the current data cursor movement step
     size.  The data cursor always moves on the Step Grid, regardless
     of whether grid markers are displayed.

     The Snap Grid display indicates the grid that the cursor will be
     aligned to when the Snap to Grid command is used.  When grid
     markers are displayed, they represent the Snap Grid.

     When grid markers are displayed, a third display, "Grid Shown",
     indicates the resolution of the displayed markers.  The grid
     markers are often spaced 5, 10, or 50 times farther apart than
     the actual Snap Grid points, depending on the current zoom scale.
     GC-PREVUE spaces the markers this way to avoid completely
     flooding the screen with grid markers.

     8.1.5 Setup

     The Setup Status Explained

     The Setup area contains parameters for viewing and editing
     layers.  Information for each layer, which is both displayed and
     changeable here, includes:

       Aperture List selection
       The View/hide setting (see Section 8.2.4)

     An asterisk after the Aperture List selection for a layer shows
     that the selection contains Invisible entries, which may affect
     the display and editing of data for that layer.

     Change the Setup

     To modify the Setup area, press the S key, or move the data
     cursor to the right until it moves out of the Viewer area and
     into the Setup area.

     To change a setup value for any layer, just put the cursor on the
     current value and type in the new one.

     Also, certain commands from the Layer list also work here:

         8: Viewing Data                    37
         _______________________________________________________

       Move Top (F8): make the current layer the top layer.

       Set Color (F9): set the display color for the current layer.

       Set... (Ctrl S): set various layer attributes for several
       layers at once.

     F10 pops up a copy of the layer's aperture list selection for
     inspection.  Inside the Setup area, ClickCenter/Ctrl M presents a
     pop up menu of these commands.

     ClickLeft, Enter and Esc all return the cursor to the Viewer
     area.

     8.2 Basic Editing Concepts

     8.2.1 Getting Help

     Use ClickCenter/Ctrl M to see a pop-up menu of commands (see
     Figure 8.2).  Press H or ? for a few more hints.

     8.2.2 Getting Out of the Viewer

     All you have to do is press the Esc key.  Since Esc is also a way
     to quit actions within the Viewer, GC-PREVUE will ask you to
     press Esc again if you want to return to the main GC-PREVUE
     screen.  If you don't, just press any other key, or move the
     mouse.

     8.2.3 Saving Your Work (F6)

     It's a good idea to save your work frequently, in case you change
     your mind about something, or perhaps there's a power loss.  The
     F6 works here just as it does in the Layer List area of the main
     GC-PREVUE screen.  To reload previously saved work, return to the
     Layer List area and use Restore (F7).  The Configure menu off the
     main menu provides for a reminder interval to occasionally prompt
     you to save your work.  We strongly recommend that you use it.

     8.2.4 Preparing to View:
     Hide or View

     Each layer can be hidden (does not display), or viewed (displays,
     can be shifted).  The setting for each layer is displayed and may
     be changed in the third column of the Setup area and is indicated
     by the character "h" or "V".

     8.2.5 Speed-up Keys (1...9)

     The keys 1 through 9 act as multipliers in cursor moves and
     zooming.  That is, once the 4 key is pressed the cursor moves
     four times as far with a single press of an arrow key, an
     unwindowed zoom changes the scale by 8x instead of 2x, and a zoom

         38                GC-PREVUE User's Guide
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     out goes up four levels instead of one.  A zoom resets the speed-
     up level to 1.

     8.3 Commands for Viewing

     In this and the following sections, each subsection describes a
     command and lists its single-key implementation in parenthesis.



















             Figure 8.2: Commands for Editing

     8.3.1 Undo (U)

     This extremely useful command allows you to reverse the most
     recent viewing action, such as, Offset or Rotate.

     8.3.2 Offset (O)

     This feature allows you to shift marked data by an explicit X,Y
     amount.  GC-PREVUE presents an input window asking for a list of
     data and the X and Y shift values.  Further shifting can be
     achieved using DragRight or by repeating the Offset command.

     The default X,Y offset values are those found in the "rel"
     display.  This allows easy point-to-point data shifting when used
     with the Zero Relative command.

     8.3.3 Rotate (R)

     This rotates any layer by 90, 180 or -90 degrees (GC-PREVUE asks
     you for the rotation).  The center of rotation is user-defined,
     the default being the center of the window, or the current cursor
     position.  GC-PREVUE has special features to aid in the rotation
     of apertures which are not symmetrical (see Section 5.1.5).

         8: Viewing Data                    39
         _______________________________________________________

     8.3.4 Mirror X/Y data (X) (Y)

     Mirroring Y means that the Y values of marked data are reflected
     or "flipped" top to bottom about a line parallel to the X axis.
     The default reflecting line is centered in the Y range of the
     window, or the current cursor Y if pointed to.  GC-PREVUE
     presents an input window that allows you to change this value if
     desired.  Mirror X behaves similarly except that data flip left
     and right instead of top and bottom.

     8.4 Panning and Zooming

     8.4.1 Pan the Display (DragCenter or P)

     To pan the display with a mouse, use DragCenter.   The start-of-
     drag position will be panned to the end-of-drag position.  For
     keyboard panning, press P and move the cursor with the arrow
     keys.  Press P again to end panning.

     8.4.2 Zoom In (ClickLeft or +)

     To zoom in on a selected area, DragLeft to make a window around
     that area, then position the cursor inside it and ClickLeft or
     press the + key.  Without a window, the zoom is centered on the
     cursor with a 2x magnification.  The speed-up keys (1...9) cause
     a corresponding 2x(speed-up) x zoom when there is no window
     involved.

     8.4.3 Zoom Out (ClickRight or -)

     This takes you to the previous zoom level.  The speed-up keys
     (1...9) zoom out by (speed-up) zoom levels.

     8.4.4 Unzoom (Alt -)

     The Alt key pressed together with the minus key on the typewriter
     area of the keyboard (not the numeric keypad area) zooms out to
     the maximum-scale zoom level.

     8.5 Drawing

     8.5.1 reDraw Now (D)

     This immediately updates the screen with all viewing changes.
     Screen redraws can be interrupted by pressing Ctrl Break.

         40                GC-PREVUE User's Guide
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                Figure 8.3: Drawing Options

     8.5.2 Drawing Mode (Ctrl D)

     This command presents an input window for changing the drawing
     behavior of GC-PREVUE, as described below.

     Style

     This toggle field has sets the style for drawing pads and traces.
     Three styles are available:

       Normal: Pads and Traces are drawn filled at width.

       Transparent: Pads and Traces are drawn unfilled at width.

       Ball and Stick: Pads are shown in outline while traces are
       shown as centerlines only.  This is the fastest drawing style.

     Negative Layers Draw In:

     This sets the color for drawing negative and composite data
     layers.  You can choose between black or the standard layer color
     scheme, as described in section 8.2.11.  In "Negative Layers:
     Black" mode, a negative layer first fills the film box with its
     assigned layer color, then draws its data in black.  A composite
     layer draws in black but does not fill the film box.

     autoDraw

     The shifting of data requires constant updating of the display.
     While GC-PREVUE attempts to update only those parts of the
     display which require it, this can still be time consuming.  You
     can gain some speed by turning off the autoDraw automatic screen
     update and just issuing a reDraw command when needed.

         8: Viewing Data                    41
         _______________________________________________________

     Slowdown

     Slowdown sets a timer for slowing down reDraw, which can
     sometimes be useful for data analysis.  The larger the number
     entered the slower the redraw speed.  Enter "0" for maximum
     redrawing speed.

     Zoom Capture On/Off

     When you zoom in, GC-PREVUE saves the current screen image prior
     to zooming.  When you zoom out again, GC-PREVUE restores the
     saved screen image.  This generally results in faster operation
     of GC-PREVUE, but in some cases it is actually faster to redraw
     the screen than to restore it, and in any event it can require a
     great deal of memory or disk space.  You can disable the zoom
     capture feature if you wish by selecting Zoom Capture "Off."

     Inverted Y Axis Orientation

     Some CAD systems represent data on an "inverted" Y axis.  An
     inverted Y axis increases in value as it moves down the screen
     away from the X,Y axes intersection.  The value of the standard Y
     axis increases as it moves up the screen away from the XY, axes
     intersection.  Turn this feature "ON" if you are more comfortable
     with the inverted display style.

     8.5.3 Label Apertures (L)

     This feature allows you to label pads and traces on-screen, by
     aperture position.  Pads are labeled at the center while traces
     are labeled at the midpoint.  GC-PREVUE waits for a keystroke
     after labeling each layer.  Any key will cause the next layer to
     be labeled, except for F10, which allows you to inspect any
     Aperture List or the Drill Rack.

     8.5.4 Wait Between Layers (W)

     "Wait Between Layers" causes the screen to be redrawn one layer
     at a time.  After each layer, GC-PREVUE waits for almost any
     keystroke before drawing the next layer.  Pressing L at this time
     labels the last drawn layer, and pressing F10 displays its
     Aperture List or Drill Rack.

     8.5.5 Aspect Ratio (Ctrl A)

     Each brand of monitor has a slightly different screen height to
     width ratio, or aspect ratio.  This can result in distortion of
     the displayed image.  GC-PREVUE provides the ability to
     interactively correct for this distortion.

     When you press Ctrl A, a rectangle appears on the screen.  If
     your aspect ratio is properly adjusted, the rectangle should
     appear to be a square.  If it is not square, use the up/down
     arrow keys to make it square.  Once adjusted, press Enter.

         42                GC-PREVUE User's Guide
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     VGA displays are assumed to have 1:1 aspect ratios.

     8.6 Grid

     GC-PREVUE works with two grids, Step and Snap, which have the
     same basic resolution.  The Step Grid determines the fineness of
     cursor moves.  The Snap Grid provides a convenient means of
     aligning the cursor or an entity to a (usually coarser) design
     grid.  Both the Step and Snap grids are taken from a user-defined
     grid selection, which is described in the next section.

     A Freehand feature is provided that allows gridless moves using
     the mouse.

     8.6.1 User-Defined Grid (Alt G)

     GC-PREVUE allows you to pick the grid sizes that best suit your
     work.  Press Alt G to pop up the grid selection window.  The
     first line G0 contains the smallest cursor movement step desired.
     On each subsequent line, Gn specifies a multiple of the previous
     line.  The Step Grid readout shows the effective grid size for
     the current line as you move up and down in the window.

     Example: if you desire an 1/8 mil grid, enter ".000125" for G0.
     This is the smallest grid step.  On the next line G1, enter 2 for
     a grid step of 1/4 mil.  For G2, enter 2 for a grid step of 1/2
     mil.  For G3, enter 2 for a 1 mil grid.  Now for G4 you might
     enter 5 (5 mil) then for G5, 2 (10 mil), and so on down to G10.
     (See Figure 8.4.)



















               Figure 8.4: User-defined Grid

     8.6.2 Change the Step Grid Size (F1/F2)

     Use the F1 key to increase the Step Grid size (i.e. move from the
     Gn grid level to the Gn+1) and the F2 key to decrease it.

         8: Viewing Data                    43
         _______________________________________________________

     8.6.3 Change the Snap Grid Size
     (Ctrl F1/Ctrl F2)

     Increase the Snap Grid size (i.e move from the Gn grid level to
     the Gn+1) by pressing Ctrl F1, and decrease it by pressing Ctrl
     F2.

     8.6.4 Snap to Grid (G)

     Press G to position the cursor, or an entity the cursor is
     marking, on the nearest Snap Grid point.  This allows you to
     manipulate the cursor with small moves, then "snap" onto the
     larger Snap Grid.

     EXAMPLE  To align an errant pad to the Snap Grid, set the Step
     Grid to a fine enough value (or use the Freehand mode described
     in Section 8.6.6) to allow centering the cursor on the pad.  Now
     Mark and Shift the pad using DragRight.  Press G and the pad
     Snaps to the nearest Snap Grid point.  You may also Mark an
     entity, press G, and the entity will Snap to the nearest Snap
     Grid point.

     8.6.5 Turn Grid Markers On/Off (Ctrl G)

     Press Ctrl G to toggle the grid markers display.  Grid markers
     reflect the current Snap Grid value, although they may be placed
     5, 10, 50 or more times farther apart to avoid crowding the
     screen..

     8.6.6 Freehand Mouse (F)

     Sometimes it is convenient to move the data cursor completely
     unrestrained by grids.  The F key toggles the use of the mouse
     between Freehand (gridless) moves and normal (grid-oriented)
     moves.  The arrow keys are always grid oriented.

     8.6.7 Zero the Relative Readout (Z)

     This command causes relative X Y offsets to be measured from the
     current data cursor position.

     8.6.8 User Zero (Alt Z)

     Specify your own absolute 0,0 position rather than using GC-
     PREVUE's absolute 0,0, which is determined from the bedsize.
     This allows you to place your data anywhere on the bed and use
     absolute offsets of X0,Y0.

     8.6.9 Units mm/inch (Ctrl U)

     Ctrl U toggles the display units from inch to mm.

         44                GC-PREVUE User's Guide
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     8.7 Miscellaneous Commands

     8.7.1 Query (Q)

     Query describes data more specifically than Label with a pop up
     window that displays pointed-to data by layer number, aperture,
     and XY location.  Simply point to or window the data that you are
     curious about and press Q.  As you scroll through the list, the
     data cursor moves to the item currently indicated by the text
     cursor.  Use Esc to quit and return the cursor to its former
     position, or press Enter to leave the cursor where it is in the
     list.



















                 Figure 8.5: Query Feature

     8.7.2 Bed Size (Ctrl B)

     Set the size of your plotter's bed here.  Press Ctrl B and type
     in the bed dimensions.

     8.7.3 Inspect Aperture Lists and
     the Drill Rack (F10)

     You can inspect any Aperture List or the Drill Rack by pressing
     F10.  When inspecting an Aperture List, press F10 again to
     inspect the drill rack.

     While inspecting an Aperture List or Drill Rack you can change
     the Invisibility of any aperture or drill using Ctrl I.  Such
     changes take effect the next time the screen is redrawn.
     Remember that data using Invisible apertures or drills do not
     display.  Layers which use Aperture Lists containing Invisible
     entries are marked with an asterisk in the Setup Status area.

         8: Viewing Data                    45
         _______________________________________________________

     8.7.4 Jump to Absolute X,Y (J)

     Press J to "dial in" a new cursor X,Y position.  Subsequent Jumps
     default to the previous Jump position, forming a convenient way
     to move between two areas of the plot.

     8.7.5 Jump to Relative X,Y (Alt J)

     Jump to Relative works just like Jump to Absolute, except that
     pressing Alt J jumps the cursor to a relative X,Y position.

           Appendix A: Aper, The Custom Aperture Generator  46
         _______________________________________________________

     Appendix A: APER
     The GraphiCode Custom
     Aperture Generator
     _________________________________________________________________


     A.1 How GC-PREVUE Uses Custom Apertures

     Custom apertures differ from other apertures in that they cannot
     be described as a simple shape such as Round, Square or Octagon.
     A custom aperture consists of a series of lines, arcs and shapes
     in a coordinate system that centers on the current plotter X,Y
     position.

     Using the APER program, you can easily describe the shape of a
     custom aperture in an HPGL-like language.  APER takes this
     description and translates it to a format that GC-PREVUE uses to
     display the aperture.  Other GraphiCode compatible products can
     also output the aperture as a series of draws and flashes,
     allowing you to use custom apertures on non-programmable
     photoplotters.

     GC-PREVUE supports the use of custom apertures for pads only.

     A.2 Using APER to Create Custom Apertures

     A.2.1 APER Basics

     APER is a simple text editor and translator that reads or creates
     human-readable (text) custom aperture description files and
     translates them to machine-readable (binary) files for maximum
     speed when used by GC-PREVUE.

     To create a custom aperture, you must first create a description
     of the aperture using APER's HPGL-like aperture description
     language.  This description can consist of rectangles, circles,
     straight lines, and arcs.  Lines and arcs can be drawn at any
     width.

     APER operates in graphics mode.  As you edit the aperture
     description text in one window, APER shows the resulting custom
     aperture shape in another window.

     A.2.2 CAT Files and CAP Files

     APER deals with two kinds of files: Custom Aperture Text (.CAT)
     files and Custom Aperture Description (.CAP) files.

     CAT files contain human-readable aperture descriptions, and can
     be prepared within APER or by using any word processor.  CAT
     files can also be largely prepared using any CAD system with HPGL
     output, but will require some modification in APER to deal with
     scaling and line weights.

           Appendix A: Aper, The Custom Aperture Generator  47
         _______________________________________________________

     CAP files contain machine-readable custom aperture descriptions,
     and can be produced only by APER.  APER reads CAT files and uses
     that information to produce CAP files.  CAP files can be read
     only by GC-PREVUE and related GraphiCode software products.

     A.3 Starting APER

     APER is a stand-alone program, so you must quit GC-PREVUE or use
     Ctrl-C to get a DOS command line.  At the DOS command line, type:

       APER

     APER uses the GC-PREVUE configuration file DEFAULT.PED to
     determine your graphics display type.  If this file is missing,
     APER will automatically determine the graphics adaptor type.

     A.3.1 Custom Aperture Text Descriptions

     Once APER is running, select Files from the main menu.  A pop
     down menu appears, with the following entries:

     Load

     Use Load to read in existing aperture description text (CAT)
     files.  Once the text is loaded, APER displays the custom
     aperture shape and places the cursor in the text editing window.
     For a list of CAT files, press F10 when APER prompts you for a
     filename.  To return to the Files menu, press Esc.



















        Figure A.1: APER Custom Aperture Generation Screen

     Save

     Use Save to write text files back to disk after editing.

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     Generate

     Use this option to generate a CAP file for use by GC-PREVUE.
     Generate cannot work unless a valid CAT file has been loaded
     (i.e., its contents are shown both in the text and graphics
     windows).

     Edit

     To continue editing the current CAT text after Save or Generate,
     select Edit.  The cursor returns to the text editing window.

     A.3.2 The CAT Data Header

     The first thing a CAT aperture description must do is declare the
     working units (inch, mil, mm or micron) and any optional
     mirroring or rotation of the working coordinate system.  This
     header takes the form:

       <units>[MX][MY][RT<degrees>]:

     <units> is one of the following:

       MM
       MICRON
       INCH
       MIL

     MX, MY and RT are used to mirror and rotate the aperture
     description.  This allows the generation of CAP files for several
     different applications, such as, emulsion up, down, and data
     rotation, with minimal editing to a single CAT file.

           Appendix A: Aper, The Custom Aperture Generator  49
         _______________________________________________________





     Header
     _______________________________

     MM    unit type
     MICRON
     INCH
     MIL

     MX    mirror X
     MY    mirror Y
     RT    rotate
          coordinates






     HPGL Commands Supported
     _______________________________

     LT   line type
     PT   pen thickness
     PU   pen up
     PD   pen down
     PA   plot absolute
     PR   plot relative
     AR   arc relative
     AA   arc absolute
     RR   rectangle relative
     RA   rectangle absolute
     CI   circle


         50                GC-PREVUE User's Guide
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           Appendix A: APER, The Custom Aperture Generator 50
         _______________________________________________________

             Figure A.2: Supported HPGL & CAT Commands



     A.3.3 CAT Syntax

     Other than in the header just described, APER CAT files use HPGL
     to describe custom apertures.  The following is a list of
     supported instructions and their arguments.  The BOLDFACE
     UPPERCASE letters are the supported instructions.  <Brackets>
     indicate required arguments, and [braces] indicate optional
     arguments.  (See Figure A.2 for a list of all supported
     commands).

     LT (Line Type)

     Format: LT[draw style]
     To select the Line Type of an aperture, choose either LT0 or LT1.
     LT0 draws with a round aperture, which results in rounded or
     half-circle end points.  LT1 draws with GraphiCode's "Slit"
     aperture, which leaves flat or squared end points.  LT0 is the
     default.

     PT (Pen Thickness)

     Format: PT<thickness>
     Set line thickness for lines and arcs.  Stays in effect until
     next PT instruction.

     PU (Pen Up)

     Format: PU[x,y,[x,y,[...]]]
     Following drawing commands update the pen position but do not
     actually draw anything.  Optional x,y movement arguments are
     interpreted as absolute or relative based on last seen PA/PR
     instruction (default is PA).

     PD (Pen Down)

     Format: PD[x,y,[,x,y,[...]]]
     Following drawing commands result in actual images.  Optional x,y
     line draw arguments are interpreted as absolute or relative based
     on last seen PA/PR instruction (default is PA).

     PA (Plot Absolute)

     Format: PA[xa,ya[,xa,ya[...]]]
     X,Y pairs for following PU and PD instructions (and optional
     movement arguments) are to be interpreted as absolute locations.

     PR (Plot Relative)


           Appendix A: APER, The Custom Aperture Generator 51
         _______________________________________________________


     Format: PR[xr,yr[,xr,yr[...]]]
     X,Y pairs for following PU and PD instructions (and optional
     movement arguments) are to be interpreted as relative offset
     locations.

     AR (Arc Relative)

     Format: AR<xr,yr,sweep>
     Draw an arc of "sweep" degrees from the current pen x,y around
     center x+xr,y+yr.  Negative sweep angles result in clockwise
     arcs.  Pen position moves to the end of the resulting arc.  PA/PR
     state is not affected.

     AA (Arc Absolute)

     Format: AA<xa,ya,sweep>
     Draw an arc of "sweep" degrees from the current pen x,y around
     center xa,ya.  Negative sweep angles result in clockwise arcs.
     Pen position moves to the end of the resulting arc.  PA/PR state
     is not affected.

     RR (Rectangle Relative)

     Format: RR<xr,yr>
     Draw a filled rectangle having one corner at the current pen
     position x,y and the opposite corner at the relative location
     xr,yr.  Pen position becomes x+xr,y+yr.  PA/PR state is not
     affected.

     RA (Rectangle Absolute)

     Format: RA<xa,ya>
     Draw a filled rectangle having one corner at the current pen
     position x,y and the opposite corner at the absolute location
     xa,ya.  Pen position becomes xa,ya.  PA/PR state is not affected.

     CI (Circle)

     Format: CI<radius>
     Draw a filled circle with the given radius, centered at the
     current pen position.  Pen position is unchanged.

     A.3.4 Differences Between CAT Syntax
     and HPGL

     Instead of the usual HPGL scaling instructions (IP, SC, etc) an
     APER CAT file must begin with one of the following key words to
     define units:
       INCH
       MIL
       MM
       MICRON


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     The MX (mirror X), MY (mirror Y) and RT (rotate coordinates)
     commands are not HPGL commands and can appear only as part of the
     data header following the units declaration.

     The PT (Pen Thickness) instruction uses the same units as other
     CAT instructions. In HPGL, PT units are always mm.  The PT
     instruction affects only line and arc drawing.  Rectangles
     (RR,RA) and rounds (CI) do not use the PT information since they
     are not arcs or lines.

     The RR and RA instructions always create a filled rectangle, and
     leave the logical pen at the far corner  of the rectangle.  In
     HPGL, they create an outline unless commanded to fill, and they
     do not update the pen position.

     The CI instruction always creates a filled circle.  In HPGL, CI
     creates an outline unless commanded to fill.

     A.4 APER Macro Feature

     APER gives you the power to create a sophisticated custom
     aperture with a Macro Command.  APER's Macro Command comes with
     on-line help, merge capacity, and pre-defined aperture shapes,
     which require only minor size adjustments for true custom shapes.
     Below is a summary of the Macro feature:

       Help: Describes APER formats
       Merge: Combines APER custom aperture text files
       Macro APER codes: Creates complex custom apertures quickly

     A.4.1 Help

     Help describes formats that APER accepts for creating custom
     aperture text (CAT) files.  Help lists an example CAT file, data
     header commands, HPGL-like commands, and APER Macro Commands.

     A.4.2 Merge

     Merge allows for CAT files to be appended to current APER editor
     data.  When a file is merged, the header will be stripped off the
     file being read in.  If no data currently exists in the editor,
     the header will remain as part of the aperture description.
     Remember, merge does not negotiate differences between headers.
     If headers are not alike, APER will create an aperture different
     from the one in the file being merged.


           Appendix A: APER, The Custom Aperture Generator 53
         _______________________________________________________


     A.4.3 Macro Commands Supported

       ANNULUS (circular and square)
       CROSSHAIR
       OCTAGON
       OVAL
       MOIRE (circular and square)
       QUAD
       DOUBLE QUAD
       THERMAL (circular and square)

     The following section describes how to use these Macro Commands.

     A.4.4 Custom Aperture Macro Syntax

     If parameters do not correspond to specified values, APER will
     try to create the aperture in the most logical manner.  For
     instance, if the inside diameter is greater than the outside
     diameter, APER will swap the values assuming that you just
     entered the data incorrectly.

     OVAL

     Format: OVAL<x,y>
     Minimum format: OV<x,y>

       Example: OVAL50,30;
























                 Figure A.3: Oval


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     The x parameter represents the diameter of the oval along the x-
     axis. Likewise, y describes the diameter along the y-axis.

     OCTAGON

     Format: OCTAGON<diameter,ratio>
     Minimum Format: OCT<diameter>

       Example: OCTAGON50,.414;

























                Figure A.4: Octagon

     Ratio is used to determine the lengths of horizontal and vertical
     sides.  The calculations are as follows:

       Lengths[top, bottom and sides] = diameter/(1+2*ratio).

       Lengths[diagonals] =
          sqrt(2*(ratio*length[top])*(ratio*length[top])).

     The value for ratio must be between 0 and 1.  If a value outside
     of 0 and 1 is given, ratio will default to .414, which will
     produce an octagon with equal length sides.

     ANNULUS

     Format: ANNULUS<outside diameter, inside diameter, shape>
     Minimum Format: AN<outside diameter>
     To create an annulus, use the keyword:


           Appendix A: APER, The Custom Aperture Generator 55
         _______________________________________________________


       Example: ANNULUS50,40,0;

























                Figure A.5: Annulus

     The AN function draws a circular or square annulus centered
     around the origin.

     Inside diameter indicates the diameter of the inner unfilled area
     of an annulus.  It is also used to determine the pen width with
     which the annulus is drawn.  The mathematical expression for the
     pen width is as follows:

       pen width = (outside diameter-inside diameter)/2.

     The default for inside diameter is 0.  If APER uses the default
     for inside diameter, the annulus will appear as a filled circle.

     Shape specifies whether the annulus is circular or square.  A 1
     indicates that the annulus is square.  0 represents a circular
     annulus.

     MOIRE

     Format: MOIRE<outside diameter, inside diameter, thickness,
     distance, shape>
     Minimum Format: MO<outside diameter, thickness, distance>.


         56                GC-PREVUE User's Guide
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       Example: MOIRE50,0,5,5,0;
























                 Figure A.6: Moire

     The MO function draws a circular or square moire centered around
     the origin.

     The outside diameter is the outer diameter of the outer ring.
     There is no default value for outside diameter.  If it is
     unspecified a "Syntax error" message will be displayed.

     Inner diameter determines the inside diameter of the innermost
     ring.  The default for inside diameter is 0.  If the minimum
     format for MOIRE is used, the default value will be used.

     The thickness parameter determines the line weight for rings.

     Distance is the space between ring centers.

     Shape specifies whether the moire is circular or square.  A 1
     indicates that the moire is square.  0 represents a circular
     moire.

     CROSSHAIR

     Format: CROSSHAIR<diameter, thickness>
     Minimum Format: CH<diameter>


           Appendix A: APER, The Custom Aperture Generator 57
         _______________________________________________________


       Example: CROSSHAIR50,.5;

























                   Figure A.7: Crosshair

     QUAD

     Format: QUAD<diameter, gap, angle of rotation>
     Minimum Format: QD<diameter>


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       Example: QUAD50,0,0;
























                 Figure A.8: Quad

     The QD function draws a quad centered around the origin.

     Gap is the space between each section of the quad.  If gap is
     specified it is guaranteed that all entities of the quad will be
     the gap distance from other entities.  The default value for gap
     is 0.

     QUAD allows the user to specify any amount of angular rotation.
     Positive and negative angles are valid.  The default value for
     the angle of rotation is 0.

     DOUBLE QUAD

     Format: DQUAD<diameter, thickness, gap, angle of rotation>
     Minimum Format: DQ<diameter, thickness>


           Appendix A: APER, The Custom Aperture Generator 59
         _______________________________________________________


       Example: DQUAD50,5,0,0;
























                  Figure A.9: Double Quad

     The diameter is the diameter of the whole double quad(not the
     diameter of the inside quad).

     Thickness determines the width of the two outside quarter rings.

     Gap is the space between each section of the quad.

     DQUAD allows the user to specify any amount of angular rotation.
     Positive and negative angles are valid.  The default value for
     the angle of rotation is 0.  If no value is entered for angle, it
     will be set to 0.

     THERMAL

     Format: THERMAL<outside diameter, inside diameter, gap, number of
     spokes, shape, rotation, angle>
     Minimum Format: TH<outside diameter, insides diameter>


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       Example: THERMAL60,45,15,2,0,45;
























                Figure A.10: Round Thermal


           Appendix A: APER, The Custom Aperture Generator 61
         _______________________________________________________


       Example: TH60,45,15,4,1,45;
























                Figure A.11: Square Thermal

     Outside diameter is the outside diameter of the outer ring.

     Inside diameter specifies the inside diameter of the outer ring.
     Inside diameter is used along with outside diameter to determine
     the line width for drawing the outer ring.  The mathematical
     equation for the width is:

       width = (outside diameter - inside diameter)/2.0;

     There is no default value for inside diameter.  If it is
     unspecified a "Syntax Error" message will be displayed.

     Gap is the space between each section of the thermal.

     Number of spokes parameter represents the number of gaps that
     will be in the thermal.  This value can be set to any number
     using the circular thermal.  The square thermal limits the number
     of gaps to 1,2,3,4,6 or 8.  If other values are entered square
     THERMAL will adjust the number to the closest legal value.  The
     default value for the number of spokes is 4.

     Shape determines whether the thermal is circular or square.  A 0
     input corresponds to a circular thermal.  1 makes the thermal
     square.


         62                GC-PREVUE User's Guide
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     Rotation specifies the angle at which a gap center will be
     placed.  For example, the thermal in Figure 9 has a gap centered
     at 45 degrees, the default value for rotation.

     Angle is used for the circular thermal only.  This parameter is a
     limit angle that places boundaries on the arc angle of each
     spoke.  For example,  if angle is set to 90 degrees, and a 2 gap
     thermal was declared the spokes would not be the full length.
     Plus the gap would be larger than the specified gap distance.
     This feature was added to allow for more flexibility.  Angle must
     be a positive value.  If it is negative, the sign will be
     stripped.  The default value for angle is 360.0 degrees.  This
     value allows for a spoke to be fully drawn with no limits.

     A.5 View Custom Apertures While You Edit

     When APER first reads a CAT file, it graphically displays the
     contents (unless the CAT file contains an invalid aperture
     description).  As you edit an aperture text description, pressing
     Ctrl Enter causes APER to re-evaluate the description text and
     re-display the aperture shape.

     A.5.1 Aper Viewing Features

     To inspect the aperture shape more thoroughly, press Enter to
     move the cursor into the graphics window.  Now you can access GC-
     PREVUE-style viewing features (press ClickCenter/Ctrl M to pop up
     menu).

     The APER Viewer is a subset of the GC-PREVUE graphical Viewer.
     The features included are:

       Pan
       Speed Up Keys
       Windowed Zoom
       Zoom In/Out
       Unzoom
       Query
       Step/Snap Grid
       Freehand mouse
       Jump Absolute/Relative
       Zero Relative

     Query operates differently in APER.  Position the cursor on an
     item of interest and press Q.  The cursor returns to the text
     editing area, pointing to the text that describes the item of
     interest.

     In addition to the familiar relative XY display, APER provides a
     third relative indicator L, which stands for Linear.  This
     readout indicates the straight line distance between the current
     cursor position and the last position where the Zero relative key
     was pressed.


           Appendix A: APER, The Custom Aperture Generator 63
         _______________________________________________________


     Note that the displayed image takes into account any mirroring or
     rotation arguments in the CAT data header.  Editing is done only
     by changing the description text - press Esc to return to the
     text window.

     A.6 Custom Apertures in Aperture Lists

     To use a custom aperture in GC-PREVUE, it must be part of an
     aperture list.  To include a custom aperture in an aperture list,
     use the APER Generate function to save the custom aperture as a
     CAP file.  Note the filename, exit APER, and return to GC-PREVUE.

     Use the GC-PREVUE Aperture List editor (see Section 5.2.3) to set
     any aperture position's type to Custom.  Then, type the CAP
     filename in the Dimensions column for that aperture position.
     When you press F1, GC-PREVUE will load the description contained
     in the CAP file.  When you save this aperture list, the custom
     aperture will be saved as part of the aperture list.  When the
     aperture list is loaded next time, the CAP file need not be
     present since its contents are preserved as part of the APR file.


         Index                        64
         _______________________________________________________


     Index
     _________________________________________________________________



     *    17, 21
     .PWK 1
     AA (Arc Absolute)   51
     Absolute X,Y   35
     Alt  7
     Aperture List  44
     Aperture Lists 13
     Aperture position   16
     Aperture Type  17
     Apertures 16
     APR  12
     AR (Arc Relative)   51
     Arc Style 28
     Aspect ratio   41
     Asterisk  17, 21, 36
     AutoDraw  40
     Automatic screen update  40
     Autosense Graphics  14
     AUX  12
     Ball and Stick 40
     Break     8
     CAP  12
     CAT Data Header     48
     CAT Syntax     50
     CGA  7
     Character set  28
     CheckPlot (Alt F4)  32
     CI (Circle)    51
     Click     7
     ClickCenter    7
     ClickLeft 7
     ClickRight     7
     COM1 12
     COMMAND.COM    12
     Copy & Resize an Aperture List (F5)     20
     Create an Aperture List or Drill Rack   23
     Ctrl 7
     Ctrl C    8
     Cursor    10
     Custom aperture     46
     Custom Aperture Description (.CAP) files     46
     Custom Aperture Text (.CAT) files  46
     Custom Apertures in Aperture Lists 63
     DEFAULT.PED    13
     Directory 11
     Display the aperture shape    62
     Does Not Run   5
     DOS  8, 12
     DOUBLE QUAD    58


         Index                        65
         _______________________________________________________


     Drag 7
     DragCenter     8
     DragLeft  8
     DragRight 8
     Drill Rack     13, 16, 21, 44
     Edit an aperture    62
     Editing an aperture list 19
     Erase     10
     EXPAND    29
     F11  19
     F12  19
     File Format Detection    30
     Filename extension  11
     Fill Adjust    30
     Flash/Draw check    28
     Freehand  43
     Gerber (RS-274-D)   26
     Graphics display types   14
     Grid 36
     Grid markers   36, 43
     Grid Shown     36
     Hercules  7
     HPGL files     29
     HPGL output    46
     HPGL scaling instructions     51
     Ignore chord tolerances  29
     Inch 10
     Inverted Y Axis     41
     Invisibility   44
     Invisible 17
     Invisible drills    21
     Job files 1
     Jump 45
     Label pads and traces    41
     Laser plotter  28
     Layers    23
     LICENSING AGREEMENT 2
     Linear    62
     Load a data file    25
     Load an Aperture List    18
     LPT1 12
     LT (Line Type) 50
     Millimeter     10
     Mirroring 39
     Modal Tool Peck     28
     Mouse     7
     Mouse Sensitivity   15
     NC drill and router 33
     Normal    40
     Offset(inch/mm)     23
     Out of Memory  5
     PA (Plot Absolute)  50
     Pan  39
     PD (Pen Down)  50


         66                 GC-PREVUE User's Guide
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     PDF  12
     PED  12
     Plotting service    33
     Point-to-point data shifting  38
     Pop-up menu    8
     Positive and negative data polarity     24
     Postscript     32
     PR (Plot Relative)  50
     Print     11
     PRN  12
     PT (Pen Thickness)  50
     PU (Pen Up)    50
     PWK  12
     PWK file  33
     Query     44, 62
     Quest files    30
     RA (Rectangle Absolute)  51
     Raster    28
     RCK  12
     Relative X,Y   36
     Reminder Interval   14, 37
     Restore work   33
     Rotation  16, 38
     RR (Rectangle Relative)  51
     Save an edited Aperture List  20
     Save your work 33, 37
     Setup     35
     Shareware License   2
     Slowdown  41
     Snap Grid 36
     Snap Grid Size 43
     Step Grid 36
     Step Grid Size 42
     T code    33
     TMP environment variable 5
     Toggle    10
     Transparent    40
     User-Defined Grid (Alt G)     42
     View Custom Apertures While You Edit    62
     View Layer(s)  31
     Virtual memory 5
     Wait Between Layers 41
     Wildcard selection  11
     Zoom Capture   41
     Zoom in   39
     Zoom out  39