[Coco] Above 512k upgrades

[jdaggett at gate.net]

On 14 Aug 2007 at 13:39, John W. Linville wrote:

> 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
-------------------------------

Correct. The current GIME would sees only one 512K block. There is no real need to extend 
the video addressing beyond what it currently sees unless you are interested in higher video 
resolutions and/or greater color depth than currently available. Either case requires a GIME 
redesign and preferably a faster MPU. 

james