7500/8500 based systems = Any Apple 7500/8500 based System. Hell I can't figure out marketing's product names so this is left as an exercise for the reader. (Hint: I bet the name is 7xxx or 8xxx and has video in or video in/out)
7500/8500 Graphics Driver
Drop on System Folder and it will be placed in the Extension folder. Reboot. Graphics Driver used for motherboard video on PowerMac 7500/8500 based system
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).
Side Effect: Apps that fade the screen to black may now jump to black immediately. Previous Graphics Drivers would not return from SetEntries/DirectSetEntries until the hardware was updated. With this new behavior, an App can call SetEntries/DirectSetEntries multiple times and fade the CLUT to black before a VBL has occurred. Hence the monitor turns black immediately.
7500/8500 based systems owners side note:
7500/8500 based systems probably came with two Megs of VRAM. If you only have two Megs of VRAM, buy two more. The video bandwidth will increase from 64 bits to 128 bits.
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.
If you have horrendous problems with these drivers (not expected), reboot and hold down "command shift N D" until the progress bar is about 1/2 done. Then remove the driver and reboot.
If you use MacsBug then you need the engineering version. If you DON'T know what MacsBug is and DON'T use it, then you DON'T need this engineering version.
However, if you use MacsBug, then this engineering version is required with the new 7500/8500 Graphics Driver.
