I was told some readers enquired about how to make up the DATA lines for the files in the program "Circuit" (EUG #23) and I am sorry these were not explained more clearly.

The program draws the components using a series of PLOT commands using VDU25. The VDU25 command is given by the program and then the three DATA values are read from the DATA lines. The number of PLOT commands (Z%) needs to be entered first so that each DATA line should read:

DATA Z%, P1, X1, Y1, P2, X2, Y2, etcWhere:

P1, P2 .............. are the PLOT codes - 4=MOVE, 5=DRAW, etc. A1, X2 ... Y1, Y2,... are the co-ordinatesThe values of the co-ordinates relate to the start point which should be regarded as MOVE 0,0.

As a simple example:

DATA 4,5,100,0,5,100,50,5,0,50,5,0,0draws a small rectangle.

I hope this has explained the making up of these lines more clearly.

I am pleased that the program has been of interest and hope it will be found very useful.

Richard Dimond

From Richard's advice, I have designed some icons to draw electrical installation drawings. I have, so far, only made a few and it is a bit labourious but once you get the hang of it, it becomes fairly easy.

Move to Mode 0. Using the grid on the first page of Appendix G in the Electron User Guide, plan out the shape of the icon you want. Do this lightly in pencil so that you can rub it out afterwards. Remember that the icon needs to be drawn sideways to the right so, for example, with a semicircle the base will be from 0,0 to say 0,40. Then the first step will be say 1,39 while the second step will be 2,38 and so on. The first number is the X co-ordinate (i.e. horizontal) while the second is the Y co-ordinate (i.e. vertical). The plot number for moving without drawing is 4 while to draw is 5. So in Mode 0, enter PLOT 5,0,40 RETURN then PLOT 5,1,39 (RETURN).

I seem to remember that Electron User published a bit of code to provide a circle plot. I will look this up and see if it is suitable.

The icons I have made are in the file 'CADIcon'.

Gus Donnachaidh, EUG #24