[Coco] OS9 and MMU operation

[L. Curtis Boyle]

Hmm… that I don’t remember off the top of my head. Good question… I can’t remember if that block is reserved for that purpose, or if it will get used, but still duplicate mapped.

L. Curtis Boyle
curtisboyle at sasktel.net



> On Jun 12, 2017, at 12:57 AM, Walter Zambotti <zambotti at iinet.net.au> wrote:
> 
> If all blocks being used then what becomes the unused block?
> 
> -----Original Message-----
> From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of L. Curtis Boyle
> Sent: Monday, 12 June 2017 2:47 PM
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> Subject: Re: [Coco] OS9 and MMU operation
> 
> The GIME definitely handles this. And I used MMU blocks in a processes' 64K memory map are mapped to the same (unallocated/unused) MMU block (so if your program goes nuts and starts writing beyond its allocated data area, it will only clobber 1 8K MMU block out of the entire system (well, unless you overwrite your own program, vector page RAM, and/or I/O area, of course).
> (If I remember correctly, MMU block $3E is the default "unused" block that is mapped in to all unused blocks in a process) 
> 
> Sent from my iPhone
> 
>> On Jun 12, 2017, at 12:34 AM, Walter Zambotti <zambotti at iinet.net.au> wrote:
>> 
>> Can any of the OS9/Nitros09 gurus say whether the memory manager 
>> allows the same physical page to be mapped into multiple MMU registers?
>> 
>> 
>> 
>> Walter
>> 
>> 
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