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From: daveh@cbmvax.cbm.UUCP (Dave Haynie)
Newsgroups: net.micro.cbm
Subject: Re: Commodore 64 Stack
Message-ID: <122@cbmvax.cbmvax.cbm.UUCP>
Date: Mon, 21-Apr-86 17:38:34 EST
Article-I.D.: cbmvax.122
Posted: Mon Apr 21 17:38:34 1986
Date-Received: Wed, 23-Apr-86 22:28:26 EST
References: <493@unccvax.unccvax.UUCP> <824@puff.UUCP> <114@cbmvax.cbmvax.cbm.UUCP>
Reply-To: daveh@cbmvax.UUCP (Dave Haynie)
Distribution: net
Organization: Commodore Technology, West Chester, PA
Lines: 24

In article <114@cbmvax.cbmvax.cbm.UUCP> grr@cbmvax.UUCP (George Robbins) writes:
>Another alternative, and this is really gross, is to have the program call
>a routine that checks the stack size, and if it's almost full, copy most of
>it to another page, and then reset the stack.  This obviously requires some
>careful housekeeping, but can be made to work. It has been used on the C128,
>where there's all that memory just waiting to be used...
>
>-- 
>George Robbins - now working with,	uucp: {ihnp4|seismo|caip}!cbmvax!grr
>but no way officially representing	arpa: cbmvax!grr@seismo.css.GOV
>Commodore, Engineering Department	fone: 215-431-9255 (only by moonlite)

There's actually absolutely no reason what so ever to do something like that
on the C128.  It has MMU registers which allow the stack (and zero page) to
be located anywhere in the 128K memory.  Its still limited to 256 bytes,
but any machine language routine that decides it needs more stack memory
can save the current SP, reset the SP, and change the pointer, of course
changing every thing back before RTSing.  Not as great as having a 16 bit
pointer, but much more sensible than copying over 256 bytes every time
you want a larger stack.
-- 

Dave Haynie    {inhp4,allegra,seismo}!cbmvax!daveh
               When the going gets tough, the weird turn pro