A83: PUSH/POPs...

To: assembly-82@lists.ticalc.org, assembly-83@lists.ticalc.org
Subject: A83: PUSH/POPs...
From: "Thomas J. Hruska" <shinelight@detroit.crosswinds.net>
Date: Sat, 03 Jul 1999 17:00:17 -0400
Delivered-To: assembly-83-outgoing@towerguard.unix.edu.sollentuna.se
Delivered-To: assembly-83@lists.ticalc.org
Reply-To: assembly-83@lists.ticalc.org


As I write this, I am looking at the Z80 Microprocessor Instruction Set
Summary by Jonathon Bowen.  Based on the PUSH/POP section, it says:

POP xx       xx=(SP)+
PUSH xx      -(SP)=xx

Where SP is the Stack Pointer register and xx is IX, IY, AF, BC, DE, or HL.
 I have two questions:

1)  Upon a PUSH, is the Stack Pointer decremented BEFORE or AFTER the
register is stored on the stack?

2)  How are the registers stored on a PUSH?  Are they stored:

FORWARD?
--------
$FD00  00 00 00 00 00 00 00 00
$FD08  00 00 00 00 00 00 00 00
...
$FFF0  00 00 00 AF AF BC HL ED


OR BACKWARD?
------------
$FE00  00 00 00 00 00 00 00 00
$FE10  00 00 00 00 00 00 00 00
...
$FFF0  00 00 00 FA FA CB LH ED


Thanks in advance!


        Thomas J. Hruska -- shinelight@detroit.crosswinds.net
Shining Light Productions -- "Meeting the needs of fellow programmers"
                   http://www.shininglightpro.com/

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Re: A83: PUSH/POPs...

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