[TheOtherHobbes]

That's still begging the question - what is a sign (symbol/signifer)?

I'd suggest it's a signifier for a subjective state. You can persuade a symbol processor to do anything to any symbol collection, but the results are only useful if the symbols mean something - which is to say they have some analog to subjective experience.

If that's the case then computers and symbol processing are tools for working with subjective experience.

This does not mean there's a possible mapping between all symbol states and all of subjective experience. It's often assumed this is true, but it's a conjecture and has never been proven. It won't be proven until we know exactly what subjective experience is.

So the best we can say is that computers are tools for working with a subset of subjective experience.

Which is interesting enough in itself without being absolutist about it.