Solution:

The DuraPoing PS/2 mouse (VP2100) can not work well with PPC-120/PPC-140. CHecking this point carefully, we get following result. The mouse can not work with CPU cards which the chipset is provided by SiS such as PCM-5868 (SiS 5582) and PCA-6154 (SiS 5598). The mouse can not work with GigaByte motherboard (GA-586STX, using SiS 5582) and the demo board from SiS (SiS 5571). The mouse work well with PCA-6159 (Intel 430TX). Fail phenomena: The system BIOS can not detect the mouse so it will not reserve 1KB memory for it. The mouse can be detected but software such as MSD.EXE and EDIT.EXE may hang randomly. The mouse driver can not detect PS/2 mouse even if mouse is connected well. In order to clarify the problem, we confirm it with followings: Modify PCM-5868 to elimate the influence from other components such as beads, capacitors, and pull-up resistors. However, all of the modifications can not solve this issue. Check the waveforms of MS-CLK and MS-DATA by oscilloscope, they are similar on different systemsa. Check the BIOS source code of mouse detecting for PCM-5868 and PCA-6159, the source code are the same. All of above results seem that this issue is caused by SiS chipset because it happens on all SiS chipset and can not be solved by any modification.