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AMD-751™ System Controller Revision Guide

22564B-1—February 2000

Preliminary Information

18

Burst Writes to Non-Existent AGP Memory Hang System

Products Affected. C3 and C5

Description. Running in DOS under Windows, MechWarrior2 creates burst writes to non-existent AGP

memory that intentionally cause master abort cycles from the S3 Savage4 graphics card to the system

controller. The AMD-751 system controller does not handle master abort cycles in the quantity

generated by the S3 Savage4 graphics card. This behavior to the system controller is caused by the

software/driver when write combining is enabled and is not considered appropriate nor indicative of

any common software technique. Write combining is enabled when the AMD AGP miniport driver is

installed.

Potential Effect on System. System hangs.

Suggested Workarounds.

I. Run the game differently:

1. Install and run the game directly under DOS, creating a BOOT floppy when asked.

2. Obtain the Windows version of the program on CD.

3. Upgrade to the newer MechWarrior3 product.

II. Change the BIOS

1. APC write chaining, device 0, function 0, register 84h, bit 17 must be left at 0.

Resolution Status. No planned fix

.