Re: A83: Re: Re:


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Re: A83: Re: Re:




The stack pointer points to the memory location in the RAM that is used
for the stack.  Now here's a little bit of useless info.  By the way,
does anyone know where thestack memory starts and ends

Basically, if there was no push command, you would have to do this:

	inc	sp		; 2 because the stack locations are 16-bits
	inc	sp
	ld	(sp),rr

Pop would be:
	ld	rr,(sp)
	dec	sp
	dec	sp

Call would be:
	inc	sp
	inc	sp
	ld	(sp),pc
	jp	xxxx		; jp actually being ld pc,xxxx

Ret would basically be:
	ld	pc,(sp)		; which would actually be impossible, because it would jump
as soon as you
	dec	sp		; loaded the pc register, so it wouldn't post-decrement the
stack pointer
	dec	sp


>
>Would someone like to explain the stack pointer in more detail?  I 
>know
>*roughly* what it does...no, actually I don't :)...
>
>Later,
>
>James Matthews (matthews@tkb.att.ne.jp)
>
>ICQ: 7413754
>http://home.att.ne.jp/gold/tomcat21/index.html
>http://library.advanced.org/18242/
>
>----------
>> From: Scott Dial (Revenant) <homosapian@geocities.com>
>> To: assembly-83@lists.ticalc.org
>> Subject: A83: Re: 
>> Date: Sunday, September 13, 1998 9:28 AM
>> 
>> 
>> Exactly that...
>> 
>> sp is a z80 register for the position of stack pointer... so that he 
>can
>> return to that exact point later. spbak is defined at the bottom: 
>spbak
>> .dw $0000
>> 
>> Patrick W Bambrough wrote:
>> > 
>> > hey can anyone tell me what this means and if there is an 83
>equivelant??
>> > ld (spbak),sp
>> 
>> -- 
>> Scott Dial
>> revenant_1@hotmail.com
>> ICQ#3608935
>

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