Mode changes

Report compatibility issues running 26-bit applications under the Aemulor Pro

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Joined: Mon Feb 24, 2003 11:43 am

Mode changes

Post by jjvdgeer » Fri Jun 04, 2004 11:25 pm

If I create an obey file with the contents:

*Echo <22><25>

and I run it, it goes to mode 25, displays the message to press space or click mouse to continue. All fine so far.

If I now go back to the desktop, I still am in mode 25! This doesn't happen normally (26-bit RISC OS or RO 5 without Aemulor). Changing the mode to 2048 x 1536 x 16m doesn't work either, but it does work if I first switch to 640 x 480 x 16m and then to 2048 x 1536 x 16m.

What is happening? Why? Can something be done about it? :-)



Post by Guest » Sat Jun 05, 2004 2:55 am

This is a known problem, and it's described in the release notes but thanks for reporting it & especially for characterising it so well! I wish all bug reports were that clear ;)

What's happening is that Pro creates a 2MB buffer for the emulated screen - this is enough for all RiscPC screen modes (well, without a ViewFinder present) and thus all the modes that Pro needs to emulate, one of which is Mode 25.

To emulate this low-colour screen, Pro tells RO5 to use that different area of memory for the screen, and also tells it the area's size. Unfortunately RO5, without Pro's intervention, uses that 2MB limit to decide whether subsequent mode changes are possible, ie. whether the screen will use no more than 2MB....of course, when changing back to a native mode (>= 8bpp) that's inappropriate.
RO5 doesn't really cope with Pro moving the screen to a different address.

You've already found the workaround, namely changing to a 16m colour, low-resolution mode before increasing the resolution.

The solution: wait until the next update of Pro. I'm overhauling most of the low-bpp screen handling to get better compatibility and performance and I'll remove this problem at the same time.

Apologies for the inconvenience.

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Joined: Fri Nov 01, 2002 10:20 pm
Location: Leeds, UK

Post by cterran » Sat Jun 12, 2004 11:21 pm

Good to hear this will be fixed. It's a bit annoying having to rearrange the screen all the time.
Keep up the good work!

Best, Chris

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