It doesn’t say in the spec, unless you interpret the memory dump for his assembled example as residing at address 0x0000 rather than offset 0x0000. But I don’t see any reason why PC shouldn’t refer to a RAM address. It would be great for code economy in such a constrained system.
It's definitely loaded into ram. Some of the operands are defined in terms of "next word of ram", which clearly refers to reading (and incrementing) the PC.
