Each program is guaranteed to have a certain number of certain types of instructions, such as (IIRC) exactly one divide instruction.
Each program is guaranteed to have a certain number of certain types of instructions, such as (IIRC) exactly one divide instruction.
Since the programs are randomly generated, there's no guarantee that any particular program always uses some number of any particular instruction. There's only a probability, X/256 instructions will be somesuch operation.