[Coco] ML Question: MMU Block Switching

[Arthur Flexser]

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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