Nice. Missing validity check on the index operation in hex2decimal though. (Funny thing, I don't see any decimals there.)

Interestingly, I think you've found a bug in the PIR syntax. It should not be legal to say $P = opcode... when the first operand of the given opcode is "inout", just "in". Your code "theURL = substr position, 3, $S1" confused the heck out of me at first.