[iyonix-support] Re: Lazy Task Swapping on Iyonix/RISC OS 5.11

In article <4499668D.4070008@xxxxxxxxxxxxx>,
   Andrew Hodgkinson <ahodgkin@xxxxxxxxxxxxx> wrote:

> FWIW, I can't imagine any circumstances that would lead to the
> problem showing up with a plain backdrop. All indications are that a
> rogue page has been mapped incorrectly. If using a plain backdrop
> there is no bitmap, compressed or otherwise, sitting in RAM that
> could be incorrectly mapped. You will almost certainly still get
> pages mapped improperly but they are unlikely to corrupt such
> visible data as a Pinboard image.

I don't know if this is a sensible suggestion or not...

Could someone write some code that copies the bytes that represent the
screen image, and have that run as soon as Pinboard has started up, ie
store the in-storage pinboard image.  I dunno if that's byte-for-byte
the same as a user's sprite file?

Then either continually run something (in a wimp poll loop) that
compares the current screen image bytes with the original set, or once
the corrupted display has happened, manually run the grabber again.

It would be interesting to know if the corruption is at the same offset
into the image data all the time, and of course what that offset
actually is.  Also what the extent (ie length) of corrupted data is,
and whether that's always the same (either per machine, or across all
machines) and whether anything else eg screen resolution, affects it.

People seem to be saying that the corruption only happens for those who
display a backdrop.  I wonder if that's actually the case - maybe it
also happens on default backgrounds but doesn't show so well?

-- 
Jeremy C B Nicoll, Edinburgh, Scotland - my opinions are my own.
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