>
>
>  The CLUT is changed by the Graphics Driver with the control
> routines SetEntries and DirectSetEntries. Previous drivers, when
> updating the CLUT would "spin loop" until the next VBL occurred and
> then update the hardware. A VBL occurs every 15 ms for a monitor
> with a resolution of 640x480@67Hz. So on average, the driver would
> spend 7 ms inside the spin loop each time the palette was changed.
>
>

The new driver saves the changes to a global variable and updates the
hardware at the next VBL. The driver now spends about .2 ms in the
SetEntries/DirectSetEntries code for each SetEntries or
DirectSetEntries call. Furthermore, 7500/8500 based machines would
clear one interrupt too many when updating the CLUT. If an App called
SetEntries multiple times in succession, the OS was prevented from
seeing a VBL interrupt. Hence the mouse would be jerky. Marathon
players who use the mouse (as all good Marathon players do) will
notice a dramatic improvement when items are picked up or opponents
destroyed (Marathon calls SetEntries/DirectSetEntries to make the
screen flash).

DL #1 7500/8500 Graphics Driver v1.3fO

Compatibility
Architecture: PPC

Graphics Driver used for motherboard video on PowerMac 7500/8500 based
system

The 7500/8500 Graphics Driver will be included in the next System
Update AFTER 7.5.5. You can throw this extension away after you get
the new System.

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