On Wed, Feb 15, 2012 at 06:04, Garrett Wollman <woll...@bimajority.org> wrote: > In article <4f39fd1a.6020...@c3energy.com>, > Ron Frazier (NTP) <timekeepingntpl...@c3energy.com> wrote: > >>Perhaps a silly question, but, does the "tick" that drives the OS >>software clock originate from the RTC or from the CPU master clock at 2 >>GHz or whatever? Just trying to understand how this stuff works. > > Customarily, there's a really cheap crystal oscillator on the > motherboard, and all of the other frequencies on the system -- except > for the battery-backed RTC clock -- are generated by a clock-generator > circuit which uses that frequency as a reference. > > Historically, the PC used frequencies which were convenient multiples > of the NTSC colorburst frequency, because NTSC crystals were really > cheap.
I believe it had more to do with the Color Graphics Adapter circuitry needing to operate at NTSC-compatible frequency.l Cheers, Dave Hart _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
