A83: Re: Opcode questions...

To: <assembly-83@lists.ticalc.org>
Subject: A83: Re: Opcode questions...
From: "Dan E" <jfsmi@geocities.com>
Date: Sun, 30 May 1999 14:43:30 -0400
Delivered-To: assembly-83-outgoing@towerguard.unix.edu.sollentuna.se
Delivered-To: assembly-83@lists.ticalc.org
References: <27a77673.2482dbf7@aol.com>
Reply-To: assembly-83@lists.ticalc.org



Yeah...the ld b,b stuff does just about absolutely nothing (doesn't even
change flags...)  ... and you were correct on the jr $+2 stuff...

-Dan



>
> 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
>

References:

A83: Opcode questions...

From: Ted21@aol.com