-----
HAM/LINK         Sec:  5
By: SAM*OH2AZG      Bytes: 2,872
Date:  4/09/86 14:40 Num: 658  
Total Downloads:   5
Title:    EASY TO USE GRAPHICS NOTATION
Keywords: GRAPHICS, DRAWING, DIAGRAMS, CIRCUIT DIAGRAMS
-----

Drawings are essential in communicating about electronics.
Circuit diagrams and other drawings are almost impossible to
convey using text. There are several graphics standards, among
others NAPLPS (ANSI X3.110) and GKS (ANSI X3.124). These are,
however, quite complicated and difficult to implement.

The following bare minimum graphics notation is easy to convert
for plotters and graphic displays in personal computers. It can
be read and drawn even without a computer. This graphic notation
is made using graphic tablets or other graphic encoders and a
simple program. It is compatible with existing text communi-
cation, filing and text processing programs. It is relatively
effective as regards storing and transmitting. However, the ease
of use having been an overriding goal in its development.

The graphics are drawn on a grid with 399 by 399 points. Points
are numbered from -199 to +199. Point -199,-199 is at the left
lower corner, point +199,-199 at the right lower corner, and
point 000,000 at the center of the screen or paper.

Drawings are made using the following commands:

M x,y      move pen or cursor from present point to point x,y
           without drawing anything (pen up)

P x,y      draw a line from present point to point x,y (pen down)

R          reset, move cursor or pen to point 000,000, middle of
           the screen, i.e. to origo, and set linetype to zero

X          finish the drawing, move cursor or pen to point
           000,000 and leave it there in non-drawing or invisible
           position

L n        select linetype n, number n being from 0 to 15,
           numbers 0 to 7 representing an unbroken line with
           colors, and numbers 8 to 15 representing dotted line
           with the same colors; devices without colors can draw
           various dotted lines

T "text"   write "text" beginning at present point lower left of
           the first character;  only horizontal text is
           possible, seven by seven points per character; charac-
           ter values from 32 (space) to 126 (tilde) are allowed

(* comment *)
           comment does not affect drawing in any way; it is only
           for the human reader


There could be more drawing commands, but it would make the
implementation of programs more complicated. For instance, there
could be a commands for drawing a circle, filling a defined area
with a given color and repeating a given series of drawing
commands (macro).

This graphic notation is intended for, though not limited, to
this system, and other telephone, packet radio, RTTY and AMTOR
based ham communication systems.

Your comments are appreciated. Please, send comments and ques-
tions to me (SAM*OH2AZG) or write REPLY here. You can also reach
me also as Q-SAM at FINHUT.BITNET.


73, Sakari M. Mattila, OH2AZG
