Dave VanHorn wrote:
>
> > >  You may be able to prevent syntax error mechanicaly by keying the
> blocks
> > > such that a connection cannot be made between two operators for example.
> > > This would simplify the code.  On the other hand, you may deliberately
> > want
> > > to allow syntax errors to improve the learning content of the toy.
> >
>  Tricky,  7 = 8 + -1 is legal.

Legal combinations are +- -+ *- *+ /- /+, while ilegal are +/ +* -/ -*
*/ /*, and I think this should be resolved by software, since the skynny
boy needs to learn what is valid and what isn't.

All modules, digits or operators, need the GroundRet connector pin, even
that at first impression you can think it is not necessary because
operators can't be used at endings, this is only valid at the right side
(3+2=5+), so the processing module should be installed at the left
side.  But academic speaking, it is important to alert the skinny boy
that "3=5+2-" is invalid, but yes at the left side as "-3=5-2", so in
all instances the processor should be able to read back the ring, then
all modules need the auto-loopback transistor.  Also different from what
I thought at first, remember that more than one "=" module can be used
at the equation, as "-6+14=5+3=10-2=7+1=24/3=2*4=-13+70/10+14=8"

Wagner.