Sv: A83: Re: Re:

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Sv: A83: Re: Re:


Not that it's very important but couldn't you just have this instead of ret:

lh hl,(sp)      ; not possible :(
dec sp
dec sp
ld pc,hl        ; not possible

Anyways, loading pc isn't possible according to the Tasm80.tab so this is quite meaningles.


***
Thomas Turn Jensen
Icq uin => 8128636
IRC, Undernet => Mukke
***
Får computeren dig til at sukke?
Så kald da blot på Mukke
***


-----Oprindelig meddelelse-----
Fra: Alan C Johnson <benjamin99@juno.com>
Til: assembly-83@lists.ticalc.org <assembly-83@lists.ticalc.org>
Dato: 13. september 1998 22:22
Emne: 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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