[Coco] ML Question: MMU Block Switching

[Richard E Crislip]

On Mon, 16 Feb 2015 22:13:43 -0600
William Mikrut <wmikrut72 at gmail.com> wrote:

> No I did not.... one of many mistakes... relocating the stack.
> 
> I am so surprised on how I have spent many, many years programming on
> modern systems from IBM to Android.... yet the 8 bit world seems to
> trip me up.
> 
> Thank you for your response!
> 
> 
> On Mon, Feb 16, 2015 at 8:38 PM, Arthur Flexser <flexser at fiu.edu>
> wrote:
> 
> > Have you got your stack somewhere safely out of the way of the MMU
> > switching?   The stack really doesn't like it when it finds itself
> > suddenly switched out of the memory map.
> >
> > Art
> >
> > On Mon, Feb 16, 2015 at 7:32 PM, William Mikrut
> > <wmikrut72 at gmail.com> wrote:
> >
> > > I do have a another ML question about memory block switching.
> > > When processing I will have a controlling program setup at $1200
> > >
> > >         orcc     #$50    Interrupts off
> > > lda $ffa1     Load current page
> > > anda   #63
> > > pshs a           Push for later
> > > lda #$36 Map in Hi-res Text
> > > sta $ffa1     Tell MMU to switch page
> > > andcc  #$ef      Interrupts on
> > >
> > > Now I can manipulate data in $2000-$3FFF and essentially display
> > > text on the hi-res text screen.
> > >
> > > When I am done and ending the program I cleanup with this:
> > >         orcc #$50
> > > puls a
> > > sta $ffa1
> > > andcc  #$ef
> > >
> > > Is there any reason that would cause a program fault while my
> > > lower
> > memory
> > > program is operating and the MMU is set to map in page 36 to
> > > $2000-$3FFF?
> > >
> > > My lower memory program is no where near $2000 in ending size.
> > >
> > > --
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> > > Coco at maltedmedia.com
> > > https://pairlist5.pair.net/mailman/listinfo/coco
> > >
> >
> > --
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> > Coco at maltedmedia.com
> > https://pairlist5.pair.net/mailman/listinfo/coco
> >
> 

Easy to move forward, not so pretty easy to go backwards 8-/.