A83: Opcode questions...

To: assembly-83@lists.ticalc.org
Subject: A83: Opcode questions...
From: Ted21@aol.com
Date: Sun, 30 May 1999 14:22:47 EDT
Delivered-To: assembly-83-outgoing@towerguard.unix.edu.sollentuna.se
Delivered-To: assembly-83@lists.ticalc.org
Reply-To: assembly-83@lists.ticalc.org


I am working on a z80 discompiler right now so that I can view the 1.07 ROM 
in all of its glory, but I've noticed some wierd things with the z80 
instructions.  I am basing my discompiler off of a text file called "opcodes" 
which is circulating around the internet somewhere and there are two specific 
questions I have.  First, for each register there is a command "ld b,b" and I 
am wondering what the purpose of something like this is because I think it is 
something like the equivalent of X->X in Basic.  Second, I have seen a couple 
of things like "jr nz,$+2" and am not entirely sure what this means.  Does it 
mean to jump two bytes ahead of the current address?  Any help you guys could 
give would be appreciated.

Ted21@aol.com

Follow-Ups:

A83: Re: Opcode questions...

From: "Dan E" <jfsmi@geocities.com>

Re: A83: Opcode questions...

From: Scott Dial <homosapian@geocities.com>