[Coco] OS9 and MMU operation

Walter Zambotti zambotti at iinet.net.au
Mon Jun 12 02:57:34 EDT 2017


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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