[Coco] Above 512k upgrades

John W. Linville linville at tuxdriver.com
Tue Aug 14 13:39:09 EDT 2007


On Tue, Aug 14, 2007 at 12:47:22PM -0400, jdaggett at gate.net wrote:
> On 14 Aug 2007 at 9:08, John W. Linville wrote:
> 
> > IIRC, isn't there something about the video memory offsets that needs
> > to be handled as well?  Sorry, I don't have a GIME reference handy to
> > ask a more specific question...

> The GIME MMU uses only 6 bits to form the part of the Address from A13 to 
> A18. Other methods extend the addressing range beyond that. IF you setup 
> extra memory as blocks of 512K, then you will  have to to little to any 
> existing software. One approach  is to have essentially super task switching 
> to where one or more programs can run in their own 512K block.

Yes, but I think you miss the point of my question.  As I recall,
if you merely extend the MMU entries to the natural 8-bits then you
will still have to keep your video in the 0th 512k block.  To be able
to allocate video frames beyond the first 512k you need a means to
extend the video addressing as well.

John
-- 
John W. Linville
linville at tuxdriver.com



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