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Frequently Asked Questions
S3 868/968 based cards - Memory Allocation Problem
Summary
Systems with an AWARD system BIOS and a graphics controller based on the S3 868 or S3 968
chip become unstable when accessing other PCI devices, like PowerVR.
Problem
During PCI initialization, graphics cards based on the S3 868 and 968 chips will request
only 32 MBytes of virtual memory rather than the 64 MBytes they actually require. AWARD
BIOS will allocate the requested 32 Mbytes to the graphics adapter and locate the add-in
card’s memory range just above that, therefore within the memory range used (but not
declared) by the S3 graphics card.
Other BIOSes like MR-BIOS have a ‘workaround’ built in which will ignore the
faulty memory request issued by those S3 adapters and allocate 64Mbytes by default,
therefore not exhibiting the problem.
Result
Attempts to use the PowerVR PCI device will fail, typically causing the system to hang or
reset.
The problem is due to the illegal memory range overlap caused by the wrong memory size
request of the S3 adapter.
Solution
Manually changing the memory allocation for the add-in card to a range outside the
64Mbytes used by the graphics card will solve the problem. The memory reallocation can be
done manually within the Windows 95 Device Manager as follows:
1) Go to the Control Panel, run ‘System’ and select
the Device Manager
2) Locate the PowerVR PCI device in Sound, Video and Game Controllers
3) Select ‘Properties’ and then ‘Resources’
4) Remove check "Use Automatic Settings" to allow manual setup
5) Choose Memory Range I from the list
6) Click on "Change Setting" and alter the range to FFBE0000 - FFBEFFFF
7) Choose Memory Range II from the resource list
8) Click on "Change Setting" and alter the range to FF400000 - FF7FFFFF
9) Confirm everything by clicking OK
10) Restart your PC
This assumes that there is no memory allocation conflict due
to devices present at FF400000-FFBEFFFF. One should cross-check for conflicts by checking
the allocated memory ranges for other PCI devices by double-clicking the computer icon in
the Device Manager and choosing "Memory".
This will allow you to run applications successfully for your
add-in card and it is normally not necessary to reconfigure the memory settings again
since Windows95 will remember the new settings every time it starts up and reallocate the
memory automatically.
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