[waynecolvin]

I suspect it would be difficult (impossible?) without relative position addressing modes and/or other tricks. A conventional stack would need some way to access an offset away from the base, but perhaps you could use self-modifying code. Perhaps relative from current position like brainfk.

All general computation needs either a direct or convoluted means of achieving conditions too. A tricky formula exploiting abs(x) could be used to produce {0, 1} but...

[lpage]

Right, my comment retarding truth tables was only in reference to combinatorial logic. That said, pure circuit models of computations exist, and are interesting from a theoretical standpoint at least. They don't translate to hardware, though. As you noted doing arbitrary computation with (finite) circuits requires some type of feedback/sequential logic.