[Coco] Re: Coco Repack

[jdaggett at gate.net]

Kevin

There can be a danger in allowing dynamic size on the fly.  Two or 
more processes with differing page size requirements are sure to  
have memory over write issues. 

james


On 8 Aug 2004 at 9:51, Kevin Diggs wrote:

Date sent:      	Sun, 08 Aug 2004 09:51:14 -0700
From:           	Kevin Diggs <kevdig at hypersurf.com>
To:             	CoCoList for Color Computer Enthusiasts 
<coco at maltedmedia.com>
Subject:        	Re: [Coco] Re: Coco Repack
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> Hi,
> 
>  I get it. The segment (block, page, whatever you want to call them)
> count is fixed at 256 (i.e. 8-bit). We can change that to if we wanna.
> 
>  And yes I do realize that NitrOS9 would have to be ... reworked.
> Maybe it should be parameterized to handle differing MMU page sizes
> anyway.
> 
>      kevin
> KnudsenMJ at aol.com wrote:
> > 
> > In a message dated 8/7/04 10:09:18 PM Eastern Daylight Time,
> > kevdig at hypersurf.com writes:
> > 
> > >   Forgive my stupidity, but why does reallocating the bits in the
> > >  address cut the max memory to 1 Meg (from 2?)?
> > 
> > Let's assume you restrict the MMU registers to 8 bits, so process
> > DAT images can be stored in one byte per segment.  8 bits means 256
> > total RAM segments, no more!
> > 
> > Currently those are 8K apiece, times 256 = 2 Megs.
> > Many of us once longer for smaller segments, like 4K, but times 256
> > is only 1 Meg total.
> > 
> > It's a tradeoff between total RAM size and segment sizes.  After a
> > lot of public head bashing against the walls, some years ago we
> > concluded that Tandy's original design of 8K wasn't so bad after
> > all.
> > 
> > Besides, it's what the DEC PDP-11 family used -- the machines where
> > UNIX was nurtured, if not born.  --Mike K.
> > 
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