Inform 7 Notes — 8 of 35

Section - The XORer - Not for release

A register is a kind of thing. Every register has a number called the rvalue. The rvalue is usually 0. The description of a register is "This register is currently set to [rvalue of the item described]."

To decide what number is the xor of (a - a register) and (b - a register): let ra be the rvalue of a; let rb be the rvalue of b; decide on ra bit-xor rb.

The xorer is a thing in The Game Room. "A high-quality xorer sits in a corner of the room, each input register ready for assignment." A register called the alpha register is part of the xorer. A register called the beta register is part of the xorer. The description of the xorer is "The xorer indicates that the xor of alpha = [the rvalue of alpha] and beta = [the rvalue of beta] is [the xor of alpha and beta]."

Assigning it to is an action applying to one value and one visible thing and requiring light. Understand "assign [number] to [register]" as assigning it to. Check assigning a number (called v) to a register: if v < 0, say "The registers are unsigned." instead. Carry out assigning a number (called v) to a register (called r): now the rvalue of r is v.