DRAW command

   1.  The "DRAW" command puts you in a graphical editor mode for drawing
       the visible picture of the gate.  It also allows you to place the
       gate's pins and "grab box".

   2.  To exit the DRAW command, press "q" or the Control-C key.  (On
       the Bobcat keyboard, this key is marked "Select".)

   3.  Gate pictures are made up of many kinds of objects.  Initially,
       you are set to draw the usual cyan vectors (line segments).
       Tap the mouse at two locations to draw a new vector between those
       points (analogous to drawing a wire in LOG).  Grab the body of
       the vector to move it; grab an endpoint to change its direction
       and size.  Move the vector off the grid to delete it.

   4.  Tap the mouse on the color or shape name to change.  Circles and
       ellipses are defined by a vector; an ellipse's diameters equal
       the sides of the bounding box of the vector, and a circle's
       diameter equals the larger of the two sides.  Filled ellipses
       are also available.  Filled polygons are defined by four points;
       to make a triangle, put two points in the same place; to make a
       larger polygon, combine several triangles or quadrilaterals.
       Rounded boxes are rectangles with circular arcs for corners.
       "Curves" are Bezier curves defined by four points; the two
       inner points govern the curve's slope at its endpoints.  Text
       objects contain a string of characters of a particular size;
       LOG will draw the characters at that size if possible, but
       will not draw them at all if there is no font small enough.
       Point-markers and box-markers are invisible placeholders which
       a gate's program may use to specify the location of some
       dynamic display such as an LED.

   5.  Some aspects of a picture can not be edited graphically.  These
       include the radius of the corners of a rounded box, and the size,
       orientation and contents of a text object.  To edit the picture
       textually, you can press the "e" key.  This is analogous to
       the EDIT command of LOGED; it runs the text editor CAGED on a
       temporary file containing the gate's definition.  See below for
       a description of this format.

   6.  The gate's "grab box" is a dotted yellow box that starts out at
       the edges of the drawing grid.  This box defines what portion of
       the picture is considered the gate's "body", for purposes of
       tapping and dragging the gate in LOG.  It should generally be as
       large as possible, but must not enclose any pins.  (If a pin were
       inside the box, it would not be possible to draw a wire to touch
       the pin.)  To move the grab box, press on any edge or corner of
       the box.

   7.  The pins of a gate are numbered consecutively from 1.  To create
       a new pin, grab one of the numbers on the left edge of the screen
       and drag it into place.  Only one pin of a given number may exist
       at a time, and when the gate is saved, the pin numbers must be
       contiguous (if there are "n" pins, they must be numbered 1 through
       "n").  Pins are forced to multiple-of-five pixel grid lines, as are
       the user's editing actions while in LOG; this makes it easier for
       the user to connect exactly to the pins.

   8.  To move all objects in a given rectangular area, just press the
       mouse at one corner of the area (with no objects under it) and
       drag out a rectangle, then move the objects into place and press
       the mouse again.  This is analogous to LOG's MOVE command.  To
       cancel the move, click the right button.

   9.  To copy another gate's picture, press "c", then give the name
       of the gate to be copied.  The current gate's picture is replaced
       by the picture, pins, and grab box of that gate.  Other aspects of
       the current gate (such as the name, labels, and definition) are
       not affected.

  10.  If you are drawing a gate which must look similar to another gate,
       you can press "s" to "shadow" that gate.  Its picture will
       appear dimly in the background of the editing grid.  To remove the
       shadow, press "s" and enter a blank name.

  11.  By default the editing grid is the exact size of a cell in the
       Catalog screen or menu area.  To draw a larger gate, press "<" and
       ">" to zoom up or down.  If the gate is larger than the default
       grid, it will be shrunk to fit in a Catalog or menu area space, but
       will be shown full-size in an actual drawing.

  12.  If you need more pins than there are numbers for on the screen,
       press "[" and "]" to change the range of pin numbers shown.
       Pin numbers may currently range up to 255.

  13.  To switch to the next or previous gate in alphabetical order, press
       the "n" or "p" key.  On a Bobcat, you can press the Next and Prev
       keys.  This is exactly like leaving DRAW mode, typing NEXT or PREV,
       and giving another DRAW command.

  14.  Other keys you can press are space bar to refresh, "!" to start a
       sub-shell, and "?" for help.

john [dot] lazzaro [at] gmail [dot] com