                  Circuit sketch
                  --------------
             Here's a program from GL 
         Maynard of Gosport for those of
             you who fancy a spot of
           electronic circuit training.
          ------------------------------

This incredible program will allow Spectrum users to make
full use of their machine's high resolution graphics to'
form diagrams of electronic apparatus and either SAVE the
results on tape or PRINT them out on the ZX Printer. An
example of the resolution possible with this listing is
shown in Fig. 1, an outdated radio circuit.

Drawing on experience

When RUN, the user will be asked to type in the numbers
corresponding to the INK and PAPER colours required. An
initial point will also be asked for; this is the point
from which the sketch is to begin from.
   The drawing of the circuit can then begin. To draw the
components, the key corresponding to the first letter of
the component should be pressed. The following represents
a list of components included in the program:

Non-polarised capacitor  - 'c'
Variable capacitor       - 'c'
Electrolytic capacitor   - 'c'
Fixed resistor           - 'r'
Variable resistor        - 'r'
PNP transistor           - 't'
Diode                    - 'd'
Inductor                 - 'i'
Switch                   - 's'
Battery                  - 'b'
Fuse                     - 'f'

Other components could easily be added should you require
them.
   Once you have pressed a certain key, the computer
requires other information as to the nature of the
component. For example, information must be given as to
whether it is to be drawn vertically or horizontally;
whether it should be drawn from the positive or negative
end; whether a resisitor is variable or fixed, etc. Once
a component has been drawn, you can draw the interlinking
lines using the cursor keys, '5', '6', '7' and '8'
to draw a line left, down, up and right respectively. The
computer will automatically allow you to start drawing
from the other side of the component, or in the case of a 
transistor, from the collector.

Going up. . .

Components may be drawn horizontally or vertically (except
the transistor), but the following rules must be noted:

1 -Horizontal components are drawn left to right.
2 -Vertical components are drawn from the bottom to the
   top.
3 -If you are drawing from left to right, the component
   must be horizontal.
4 -Transistors are drawn horizontal, beginning at the
   base and ending up at the collector.
5 -Variable components are drawn from the central arrow
   position and terminate at the right or top end.

The current plotting position is always displayed; if you
want to draw accurately or PRINT in component numbers or
values at a later stage, you would be wise to note down the
position of each component.

   You may not draw off the screen; you will be stopped by
the contents of line 64. However, you are allowed to change
the plotting position by pressing the 'p' key and stating
the co-ordinates of the new position. The variable screen
is set to zero if further drawing will result in the line
going off the screen.
   Once the circuit has been completed, you can press the
Break key and, using PRINT, mark in any additional script
onto the diagram. Should you wish to SAVE the program, try
using the following:

SAVE "circuits" LINE 2

This will allow the program to RUN automatically when 
re-LOADed.
   Should the thought of playing around with electronic
circuits scare you to death, try using it as a simple
sketchpad.