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        By far the greatest number of phone calls we receive at ACCEL for
        technical support  involve the generation of Gerber photoplot and
        N/C drill  files from Tango-PCB.  This is despite Tango's logical
        approach to  the problem,  and a  detailed, illustrated,  26-page
        chapter on  the subject  in the  Tango-PCB  Series  II  reference
        manual.   The CAM Output chapter in the reference manual gives an
        excellent overview  of photoplotting and drilling in general, and
        describes each  option on the various Output Apertures and Output
        CAM command dialog boxes.  By all means we recommend you take the
        time to read it prior to generating any CAM files.
        
        We are  supplementing the  reference materials with this tutorial
        which takes  you step-by-step  through the  process of generating
        CAM files.
        
        In general, the steps in generating photoplot and drill files are
        as follows:
        
        1.   CHAPTER 17.   Read  the CAM  Output chapter in the reference
             manual.
        
        2.   OUTPUT REPORTS.   Use  this command to generate the Aperture
             Information report.   Always  generate this  report first to
             see what apertures have already been described and assigned.
        
        3.   OUTPUT APERTURES.  This command is used to:
             3.1  Describe the apertures you want to use.
             3.2  Describe the  tools you want to use.
             3.3  Assign the apertures and tools to specific items on the
                  board, such as tracks, pads, etc.
        
        4.   OUTPUT REPORTS.   Use  this command to generate the Aperture
             Information report  again, this  time to  make sure that all
             items on  your board  have been  correctly  assigned  to  an
             aperture or  tool.    If  there  are  incorrect  or  missing
             assignments, they should be fixed at this point.  The report
             is designed  so you  can give  it to your service bureau (in
             hardcopy form,  or on  a disk  with your  CAM  files),  thus
             documenting your  efforts  and  protecting  you  from  later
             finger-pointing should problems arise.
        
        5.   OUTPUT CAM.  Use this command to:
             5.1   Define what  will be  in each  CAM  file.    There  is
                  generally a  separate file  for each  board layer to be
                  photoplotted.
             5.2  Define the N/C drill file.
             5.3  Create the photoplot and drill files.
        
        Tango-PCB Series II ships with a definition file which includes a
        variety of  common pads,  tracks, strings  sizes, etc.,  and  the
        aperture definitions  and assignments  for these  items have been
        established for  you.   If you  build a board without adding your
        own custom  components, pads  and tracks,  most of  the  work  in
        preparing CAM files has been done.  If you have customized Tango,



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        you  will  be  updating  our  supplied  defaults  with  your  own
        particular setup.
        
        We'll assume  you have read the CAM output chapter in the manual,
        and have  generated the  Aperture Information report to see which
        apertures have  already been  described and assigned for you.  So
        let's begin now with step 3, the Output Apertures command.
        
        
                      STEP 3 - THE OUTPUT APERTURES COMMAND
        
        Before you  begin you  must know  which type of photoplotter your
        bureau  is   using,  a   laser   photoplotter   or   conventional
        photoplotter.   A laser photoplotter is software driven, and thus
        allows you  to use  draft codes  D10 through D99.  A conventional
        photoplotter is  limited to the 24 stations on the aperture wheel
        itself and  therefore you may only use a total of 24 draft codes.
        See Chapter  17 for  a listing  of which  draft codes match which
        station numbers on conventional photoplotters.
        
        The subject board for which you intend to generate CAM files must
        be loaded  during the  operations described below, so load it now
        if you have not already done so.
        
        3.1  DESCRIBING APERTURES
        
        Select Output Apertures from Tango's menus.  The first dialog box
        is titled  Describe Apertures.   This  is where  you  create  the
        apertures descriptions for specific draft codes.  You first click
        on the  D-Code box and input a draft code, such as "10" for draft
        code D-10.  Next key in values in mils in X Dim and Y Dim fields.
        Even draft  codes for  lines need  both X  & Y dimensions because
        they are  plotted with an elliptical aperture so that the ends of
        lines are  rounded.   If the draft code you are creating is for a
        pad, you  may input  a dimension  under H  Dia, but be forewarned
        that this  will result  in the pad being photoplotted with a hole
        and having  a distinct  resemblance to  a chocolate  donut.    We
        recommend leaving  the hole dimension zero.  This does not relate
        to the drill size at all--we'll get to that a little later.
        
        Now select  the shape of the aperture.  Lines should be described
        as ellipses, pads can take any of the shapes listed.  Next select
        whether the  aperture is  flashed, drawn,  or both.    Lines  are
        always drawn,  but pads,  whenever possible,  should be  flashed.
        Flashing items  rather than drawing them saves an enormous amount
        of data  in the  resulting photoplot file, and can save you a lot
        of money  if you  are still  plotting  on  conventional  (vector)
        photoplotters.   But not all pad shapes and designs are available
        on conventional  photoplotters, so  they may  need to  be  drawn.
        When in  doubt, consult your service bureau to see what apertures
        are available.
        
        You should now add a comment for the draft code you are defining.
        Typical comments  are "8  Mil Round  Draw" for a draft code for 8



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        mil lines;  or "50 Mil Round Flash" for a draft code for a 50 mil
        pad.
        
        Finally, don't  forget to  ADD the  new draft code to the list by
        clicking on Add.  Lot's of people forget this step.  When all the
        draft codes  you need  have been  defined, select OK to go to the
        next step, the Describe Tools dialog box.
        
        3.2  DESCRIBING TOOLS
        
        The Describe  Tools dialog  box is  the sister  to  the  Describe
        Apertures dialog box.  Here we describe tool codes which are used
        in generating  the N/C  drill file, just as the apertures we just
        described are used in generating the photoplot files.
        
        A tool  code, or  T-Code, is  a  reference  to  a  specific  hole
        diameter.  To add a new value, input the new number in the T-Code
        entry box (example: "7" for T07). Input the drill bit diameter in
        mils in  the Dia  entry box.  Do this for each hole size you have
        on the  board.  Most boards require only 4-5 drill sizes, but you
        can define  up to  13 drill  codes and each can be represented by
        unique symbols  when a  drill drawing is generated.  Once this is
        done you  hit OK and you are swept to a third dialog box which is
        the most  important (read:  many mistakes  are made  here) of all
        three.
        
        3.3  ASSIGNING APERTURES AND TOOLS TO ITEMS ON THE BOARD
        
        In the  Assign Apertures  and  Tools  dialog  box,  we  take  the
        apertures and  tools which  we just  defined and  assign them  to
        specific items  which appear  on our  particular board.  This may
        seem like  an unnecessary  step if you have a 50 mil round pad on
        the board  and you  just defined  a 50  mil round flash aperture.
        Sure, Tango  could do  the assignments  for you, but allowing the
        user to  make the  assignments affords  a lot of flexibility that
        you will surely come to appreciate.
        
        To photoplot  any item on your board, you have two basic options:
        assign it  to a  draft code  aperture which  you have defined, or
        just draw the item with the "default Draw" aperture.  The default
        Draw aperture  that is  in  the  PCB  definition  file  when  you
        received the  program was  D11, 10  mil round draw.  This default
        draw aperture  size can be changed by clicking on Draw and keying
        in a  new value.  The default Draw aperture is used on items that
        are not flashed, like text, certain pads, and area fills, but can
        also be assigned to any other item on the board.
        
        More commonly,  however, you  will assign  D-codes to items which
        match their  characteristics,  like  a  "50  Mil  Round  Flashed"
        aperture for a P_EL_0050_0050_028_AL pad.
        
        To make the assignments, select the first item in the Description
        list box, which will usually be a line.  When you select the line
        you will  notice that  the options  to the  right are crossed out



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        except for  Normal.  Click on normal and a selection dialogue box
        appears.   You are  presented with  a  choice  of  assigning  the
        default Draw  aperture, or any of the defined apertures.  Use the
        cursor keys  to scroll  down through the list until you reach the
        correct daft  code for  that item.  If it were an 8 mil line, for
        instance, you  might select  draft code  D-10, 8  Mil Round Draw.
        Click on  OK and  you have  just assigned  your  first  aperture.
        Congratulations!
        
        Move the cursor in the Description list box down to the next item
        and if  it is  a line,  click on  Normal again  to make your next
        assignment.   If the  item in  the list  box is  a pad,  then the
        Normal option  remains and the options S Mask, Plane, and Thermal
        reappear.  Click on Normal to assign the aperture you want to use
        to represent  your pad  on signal  layers  of  the  board.    The
        selection dialog box reappears.
        
        For each pad, you may also wish to assign different apertures for
        the solder  mask, power  and ground  planes, thermal  reliefs and
        drill symbols.  Click on S Mask.  Now select an aperture which is
        larger than  your pad  to allow for clearance on the solder mask.
        Normally, we  recommend an  aperture approximately 10 mils larger
        than the  pad,  but  consult  your  board  manufacturer  for  his
        requirements.
        
        Next click  on Plane  and select  an aperture 10 mils larger than
        your  pads  (again,  consult  your  board  manufacturer  for  his
        specifications).   This will  result in  a photoplot, done in the
        negative, which  will provide adequate clearance for your pads on
        the power and ground planes.
        
        Forgot to  define apertures 10 mils larger than your pads?  We'll
        forgive you  and give  you two  options:  select the default Draw
        aperture (but  remember, this  increases file  size), or  just go
        back and define the desired aperture now.
        
        If the  pad in  question has  a thermal  relief connection to the
        power or ground plane, click on Thermal to select the aperture to
        be used.
        
        Continue this process for all lines and pads, and you'll have all
        the assignments you need for generating a photoplot file for your
        board.  But don't stop yet.
        
        Continue to  scroll down  to the  next section  of items  in  the
        Description list  box which  will be  the HOLES on the board.  In
        order to  generate an N/C drill file, you need to assign the tool
        codes you  previously defined  to the  holes which  are  on  your
        board.   If you  select a  hole from  the list  to assign, you'll
        notice that  the options  enabled are  Drl Sym (for drill symbol)
        and Tool.
        
        First click on Drl Symbol and a selection dialog box appears with
        a list  of drill  symbol apertures.   Before defining draft codes



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        for drill  symbols, you  may want  to consult  with your  service
        bureau to see what symbols they have available.  A simpler method
        is to  select the default Draw aperture, and then Tango will draw
        up to  13 unique  drill symbols which are defined in shape by the
        program.  Click on OK after selecting the default Draw aperture.
        
        Next select  the Tool  option.  The Hole Diameter dialog box pops
        up with  the tool assignment you have previously described.  Just
        select the correct hole size and click OK.
        
        Continue this process for each hole, as you did for the lines and
        pads.   When you  are certain you have made an assignment for all
        items in the Description list box, click on OK.
        
        You have  now completed  all the  set up necessary for generating
        photoplot and  N/C drill  files.    You  defined  both  photoplot
        apertures and  drill tool  codes, and  then  you  assigned  those
        apertures to  pads, lines,  etc on  the board,  and you  assigned
        those tool codes to the various size holes on the board.
        
        
                    STEP 4 - THE APERTURE INFORMATION REPORT
        
        Now is  the time  to use  the Output  Reports command to generate
        another copy  of the  Aperture Information  report.   This report
        will clearly  indicate all  apertures and  tool  codes  you  have
        defined.   It will  also provide  a listing  of all  items (pads,
        lines, holes,  etc) on  the board and which aperture or tool code
        you have assigned to them.
        
        The report also indicates any item on the board that you have not
        assigned an  aperture or  tool code.   If  you try  to generate a
        photoplot file or N/C drill file which includes an item which has
        not  been  assigned  to  an  aperture  or  tool  code,  the  file
        generation will  stop and  an error  message will be issued.  You
        can avoid  those beeping  error messages  by using  the  Aperture
        Information report  to be  sure that  all items  on the board are
        properly assigned.
        
        Once you feel you have your definitions and assignments in order,
        print one  last copy  of the  Aperture Information  report.  This
        becomes your  record of  what definitions and assignments were in
        place when  you generated  your CAM  files, and  thus becomes  an
        important part  of your design documentation.  The report is also
        designed to  provide the  service bureau with all the information
        he needs  to generate your photoplots or drill your boards, along
        with the CAM files themselves of course.
        
        
                        STEP 5 - GENERATING THE CAM FILES
        
        Now select  the Output CAM command from Tango's menu.  Before you
        actually generate  the CAM  output files,  you are presented with
        the Set  Language Options  dialog box.   Here you set options for



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        both photoplotters  and N/C  drill  machines.    We  suggest  you
        consult your  service bureau  for the  options applicable  to his
        equipment.   Chapter  17  in  the  reference  manual  includes  a
        description of  each option.   When you have set all the options,
        click on OK.
        
        5.1  DEFINING THE CONTENTS OF EACH PHOTOPLOT FILE
        
        You are  now going  to define what each of your photoplot and N/C
        drill files  will include.   This  is a  very important  section,
        (read: even  more mistakes are made here), because if you put the
        wrong items  on a  layer, or leave other items off, you are going
        to waste  time and  money at  your photoplotter.  For instance, a
        possible error  is when you define the items to be plotted on the
        top layer  and then  move to  defining items for the bottom layer
        but accidentally leave the top layer on.  The result is a plot of
        both layers  on one piece of film and acid indigestion.  But take
        heart, the  Define CAM  Files dialog  box makes  this an easy and
        normally painless process.
        
        To set  up your  first photoplot  file, pick  the items  you want
        plotted  together   in  that   file  in   the  "Enabled   desired
        layers/items" selection  box.   You can combine items on the same
        plot, such  as "Top"  for the top layer lines, fills, text, etc.,
        along with "Thru Pads," "Vias," and perhaps "Board" for the board
        outline on the board layer.   An X appears in the box to the left
        of any item chosen.
        
        If you  want the photoplot layer to display reference designators
        or component  types, or  if you want a mirror image of the layer,
        select those  items in  the  options  area  of  the  dialog  box.
        (Generally we do not recommend generating the mirror image of the
        artwork because the mechanical variations in all plotting devices
        can cause  registration problems  between layers  which have been
        mirrored).
        
        Once you  have selected  items you  want in  the plot,  click  on
        Filename Ext to give the photoplot file an appropriate extension.
        Other options which may be set include X and Y offsets, power and
        ground swell, solder mask swell, and drill symbol size.
        
        The power  and ground  swell, and  solder  mask  swell  are  only
        applicable if you have chosen to DRAW your pads.  If you selected
        a defined aperture for the planes and for the solder mask, recall
        that you  have already  picked an aperture that is 10 mils larger
        than your pads to give you the necessary clearance.
        
        The drill symbol size sets the dimension for the height and width
        of the  drill symbol  to be photoplotted.  If you took our advice
        above and  assigned the  default Draw  aperture to draw the Tango
        drill symbols,  then they  will contain  lines with  a  thickness
        equal to the default Draw aperture.
        




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        Once all  the options  are set, click on ADD to add your CAM file
        to the  CAM File  Queue.  If you are attempting to add a CAM file
        with the same extension as one already in the CAM File Queue, the
        program will  ask if  you want  to replace that file or abort the
        operation.
        
        You can  now proceed  to define and ADD to the CAM File Queue all
        the photoplot  files you  wish to generate.  Most are pretty self
        explanatory, but here are few things to keep in mind:
        
        When generating a silk screen, either top or bottom, don't forget
        to turn  Thru Pads  and Vias  OFF, and  Ref Des  (and maybe  also
        Types) ON.
        
        When generating  a drill  drawing, in addition to Drill Dwg, Thru
        Pads and  Vias MUST  be turned  ON.   The  Board  layer  is  also
        typically turned on.
        
        5.2  THE N/C DRILL FILE
        
        The N/C  drill file  is also  added to  the CAM  File  Queue  and
        generated at the same time as the photoplot files.  To set up the
        N/C drill  file,  turn  on  N/C  Drill  in  the  "Enable  desired
        layers/items" selection  box.  All other items will automatically
        be turned  off.   Click on  Filename Ext  and type  in a filename
        extension.  We recommend using the extension .NCD so as not to be
        confused with  .DRL which  is normally used for the drill drawing
        photoplot file.
        
        5.3  GENERATING THE CAM FILES
        
        The moment  is here at last.  You have defined apertures and tool
        codes, assigned  them to  items and  holes on your board, defined
        what will  be in  each of the photoplot files and created a queue
        of photoplot and N/C drill files to be created.
        
        Any files  in the CAM File Queue with an asterisk "*" beside them
        will be generated automatically when you click on OK.  To turn on
        or off  the asterisk,  simply click on the file name in the list.
        (If you don't have a mouse, use the tab key to move the highlight
        to the  list box,  then use  the cursor  keys to pick the file in
        question, and  then press  the spacebar  to turn  the file  on or
        off.)
        
        Now just  click on  OK and Tango will begin generating the files.
        A "pacifier"  dialog box  is displayed which indicates which file
        the program  is generating.   The  status line  at the top of the
        Tango screen indicates which items within that file are currently
        being created.   The  CAM files  are written  to disk in the same
        subdirectory as where your Tango program files reside.
        
        All that  remains is  to modem  or disk  them off to your service
        bureau along with the Apertures Information report.  This may not
        be as  easy as  it sounds,  if the files are large.  If the files



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        are very  large, it  is probably  the result of using the default
        Draw aperture  on pads  instead of  the flash  apertures.  It may
        also be  the result  of large  area fills on the board, which are
        plotted with  the default  Draw aperture (which you may recall is
        set at  a small value, like 10 mils, because it also used to draw
        pads and  drill symbols).   Large files also result from a lot of
        text on the board, since each character actually consists of many
        small vectors which are drawn.
        
        There are  three options  for transferring  files to your service
        bureau which  are larger  than  your  floppy  disk  will  handle.
        First, try  using a  modem if  you and your bureau each have one.
        This is  the way  to get the fastest service from your bureau and
        there is  virtually no size restriction.  Secondly, try archiving
        the photoplot  files using  a public  domain archive program like
        PKARC.   Third, you  can use the DOS command BACKUP to backup the
        file across  multiple diskettes.   Just  be sure  your bureau  is
        running the  same version of DOS when he tries to use the RESTORE
        command to copy the file onto his hard disk.
        
        We hope  this document  helps to  take some of the mystery out of
        generating photoplot  and N/C  drill files  with Tango-PCB Series
        II.   We appreciate  your taking  the time  to read it.  While we
        always willing  to answer  your questions  by Fax or phone, it is
        becoming increasingly  difficult to  give good  technical support
        service to  those who really need it when the lines are cluttered
        with calls from those who refuse to read the documentation.
        
        As always,  we appreciate  your support  and interest and welcome
        any  and  all  suggestions  for  improvements  to  our  software,
        documentation, and customer service.
        
        ACCEL Technical Support
        























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