           opcode        func(last 4)

ALU op    100000             0000         AND
          100001(Imm or dis) 0100         ADD
                             0111         SUB
                             1000         OR
MUTL      100010                          MUTL
MUTLI     100011

LD        110000
LDI       110001             xxxx         Imm  addressing

SW        111000             xxxx         
SW        111001             XXXX         displace addressing

BEQZ      111100

