I just completed project 1, and as I went through building the various chips, I found myself naming internal pins in a variety of ways, like a_or_b, aorb, orab, w1, sel101, sel00x, etc.
I even found that some of my chips got syntax erros if I used underscores in the names, whereas others did not.
What are the commonly used naming conventions for these?
The only documented characters that are legal for pin (wire) names are upper- and lower-case English alphabetic and numerals 0-9. Undocumented (aka BUG) '-' and '.' are allowed as second and following characters.
I name simple signals in lowercase, like the book uses for most I/O names.
For derived signals I usually use camelCaseNames that describe the derivation. For example
If the signal is a specific bit in a word I append the bit number.
FullAdder(a=a, b=b, c=carry3, sum=out, carry=carry4);
Sometimes, for important parts like the DRegister in the CPU, I name the signals based on the part name:
DRegister(in=dRegIn, load=dRegLoad, out=dReg);
Try to avoid names that are too similar. In the ALU there are two functions Add and And. I call the signals resulting from those operations 'and' and 'sum'.
And, alas, when I'm feeling lazy I use 'w1', 'w2' if they only connect from one line to the next line or two...
(I've never seen '_' work in a name. If you still have an example of it working, I'd love to see it.)