[Coco] 6309 microprocessor project 01-16-2004

[John Collyer]

Again,

Since this version of the emulator will require a 586
preferably a Pentium I am assuming these block
moves of 8k will require very little time, but I can
see how this might effect NitrOS-9 or OS-9
Level 2 though.  How much time does NitrOS-9
or OS-9 Level 2 kernel spend switching MMU
pages as opposed to getting or putting bytes
without the MMU page being changed.
change.

John Collyer

----- Original Message ----- 
From: "John Collyer" <johncollyer at zoominternet.net>
To: <coco at maltedmedia.com>
Sent: Friday, January 16, 2004 2:26 PM
Subject: [Coco] 6309 microprocessor project 01-16-2004


> 6309 microprocessor project.
> 
> Hello,
> 
> I decided for the memory functions I would use a dedicated 64K
> memory extent.  I tried the other way, which used pointers to 8k
> memory regions.  This allowed for singlebank and fixbanks to only
> change the memory pointers when needed, but increased getbyte
> and putbyte's complexity.
> 
> Since getbyte and putbyte are constantly being used as opposed to
> singlebank or fixbanks it was a easy decision.  This was the most
> convincing argument for the choice.
> 
> Also with using the pointer method the special opcodes $11FD
> and $11FF were confined to 8k memory boundaries.  With the
> dedicated 64k memory extent using these special opcodes can
> exist anywhere in the 16MB physical memory space because
> singlebank and fixbanks not only calculate everything but also
> blast the 8k banks to the 64k address space so the 64k memory
> extent always contains the right banks, and getbyte and putbyte
> are then greatly simplified.
> 
> This goes against the grain, so to speak.  Usually you'd want to
> change pointers instead of moving memory chunks around, but
> not in this case.
> 
> I was still wondering what the emulator lacks in making the
> Sockmaster demos work?  Any insights will be appreciated.
> 
> John Collyer
> 
> 
> 
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