Tag: timing

SOLUTION: Sylvania G and Windows XP timing issues

Posted on by Jody Bruchon

Thanks to a helpful developer at the ZSNES forum, we found the solution to the VIA C7 platform speed/timing problems with certain programs.

Edit C:\BOOT.INI and add the /usepmtimer switch to the boot command line for Windows XP. This uses a timer that is stable even when in power management modes, which means that the throttling of the C7 CPU and accompanying chipset do not affect its timing characteristics.

Some applications like ZSNES rely on a very precise and stable timing mechanism (in the case of ZSNES, speed regulation depends on QueryPerformanceCounter) and the normal timer on this platform is unstable in certain power management states. Also, we used WCPUID’s real-time clock display to figure out that the System control panel (sysdm.cpl) reports the frequency wrong on the C7 and that it is in fact running at 1200 MHz when under a full load, despite Windows’ insistence that somehow the CPU is going as low as 198 MHz when the lowest ACPI P-state is 400 MHz.

If you have games on this netbook and are experiencing strange timing jerks or other glitches, you need this simple fix.

Sylvania G’s VIA C7-M versus Windows XP

Posted on by Jody Bruchon

I changed my Sylvania G (original, non-Meso) netbook to Windows XP/Linux dual-boot to test some software I’m working on, and discovered that while Windows XP certainly does boot and run in general on the G, some kind of system timer or timing loop is severely out of whack! I wanted to use my little G as a portable gaming machine from the Windows XP install, and to my horror, ZSNES couldn’t decide what speed it wanted to run! Now, I’ve never had a single issue with ZSNES on any computer I’ve ever tried it on, even preferring the Windows port of it over the Linux native one, and not once has a problem existed with ZSNES that I couldn’t find an easy fix for, until now. I’ve been researching the matter and gathering evidence, and I may have a potential answer to the problem.