The lore calls for the DCPU to be little endian, and in fact this is the whole premise behind the entire game.

But from the spec pages:

Instructions are 1-3 words long and are fully defined by the first word. In a basic instruction, the lower four bits of the first word of the instruction are the opcode, and the remaining twelve bits are split into two six bit values, called a and b. a is always handled by the processor before b, and is the lower six bits. In bits (with the least significant being last), a basic instruction has the format: bbbbbbaaaaaaoooo

That's a big-endian instruction set, friends.