Curious note: the opcode space of the Z80 was best viewed in octal, not hex. The first 2 bit decoded the instruction class e.g. 01 was the MOV set of instructions. The next 3 bits were register destination; the last three were register source?

Registers were numbered [0-7] b,c,d,e,h,l,m,a if I remember right. h and l were 'high' and 'low' part of the 16-bit indirect 'm' memory address.

So in octal, 134 was "mov e,h".

You now know 1/4 of the entire Z80 instruction set!