MiniISA has four registers: $1, $1, $2 and $r, represented as 00, 01, 10 and 11
respectively.

0000aaxx        load $a         load into register a from address in $0$1
0001aaxx        store $a        store from register a into address in $0$1
0010xxxx        jump            jump to address in $0$1
0011oooo        jump o          jump o instructions (signed)
0100iiii        high $0 i       high bits of register 0 set to iiii
0101iiii        low $0 i        low bits of 0
0110iiii        high $1 i       high bits of 1
0111iiii        low $1 i        low bits of 1
1000xxxx        sub             $r = $0 - $1
1001oooo        branch o        if ($r < 0) jump o instructions (signed)
1010aabb        swap $a $b      $a and $b are swapped
1100xxxx        srl             $r = $0 >> $1 (logical)
1101xxxx        sra             $r = $0 >> $1 (arithmetic)
111xxxxx        sll             $r = $0 << $1