Changes
Z80
,/* Optimization */
* DJNZ loop is one byte smaller and is as fast as DEC B; JR nz,loop on CPC.
* Unconditional JR is one byte smaller and is as fast as unconditional JP on CPC.
* For a smaller conditional RST #38, use JR cc,-1. This will cause a conditional jump to the displacement byte (#FF) which is the RST #38 opcode.
* To set A to zero, XOR A is one byte smaller and one M-cycle faster than LD A,0.
* To check if A is zero, AND A or OR A are one byte smaller and one M-cycle faster than CP 0.
