Re: [stella] Stack pointer. Some questions

Subject: Re: [stella] Stack pointer. Some questions
From: Christian Bogey <khryssun@xxxxxxxx>
Date: Sun, 9 May 2004 14:23:41 +0200 (CEST)

The Stack is an internal 8 bits register of the 6502
CPU. It works countdown.

> Where is it ?
> at the end of the 128 bytes of ram ? 
well everywhere you want but indeed in VCS programs it
is better to located at address #$FF (the end of ram)
using the commands :

> If so can you address it like a normal 
> variable ?

not really, "Playing" with stack is related to special

Some commands are related to Stack operations :
PHA : Push accumulator on stack
PLA : Pull accumulator from stack
TSX : Transfer Stack pointer to index X
TXS : Transfer index X to Stack pointer.

it's modified by operations like JSR (return address
is pushed) and RTS (return address is pulled)too.

Take care 

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