Ticket #315 (Fixed)Tue Sep 18 21:42:48 UTC 2012

ScreenModes mode selection logic needs improving

Details by Jeffrey Lee (213):

Now that the VIDC & bandwidth limiting code has been stripped out of ScreenModes, the module is now less effective at selecting sensible modes on IOMD/VIDC hardware than it was before.

E.g. my RiscPC has several 1280×1024 modes in its MDF, each at different refresh rates. Some of these refresh rates require a pixel rate of over 110MHz, so aren’t actually suitable for use on a RiscPC. The WimpMode command in my PreDesk folder selects 1280×1024×256 but doesn’t specify a refresh rate. On RISC OS 3.7, and on versions of RISC OS 5 prior to the VIDCBandwidthLimit removal, this WimpMode command works fine and ScreenModes is able to skip the bad modes. But on the current version of RISC OS 5 ScreenModes doesn’t seem to make any attempt to skip/filter out the bad modes, leading to the mode change failing once it reaches VIDC20Driver. The only way to successfully change to a 1280×1024 mode is to manually specify the refresh rate in order to avoid the auto-selected rate from failing.