Hal, I have two Prolific adapters on a single hub, which is probably low speed (it was cheap). They work fine under XP, even though one of them is used with a program (development system) that has shown some finicky behavior when driving a serial input JTAG box with the old drivers. The other one drives my ham radio's serial port. The Thunderbolt is normally plugged into the hardware serial port COM 1 on this machine, I will try with the Prolific adapter just for grins.
Didier KO4BB > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Hal Murray > Sent: Wednesday, June 25, 2008 7:03 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Thunderbolt and USB to RS232 converters > > > > That's a good point. The older Prolific drivers had a nasty > habit of > > crashing my laptop (Win XP would not wake up) if I put it in > > hibernation with the adapter plugged into the USB socket. The new > > drivers mostly fix the problem. I may occasionaly have to > unplug and > > replug the device after waking up, but the OS no longer crashes. > > The SIRF GPS units use the Prolific chips. > > I have had mixed results with them on Linux. > > They don't work like I expect when I try to use several of > them on a high speed hub. The Prolific chip wants some > guaranteed bandwidth and Linux has troubles allocating it. I > thought I found a kernel option to get around that, > CONFIG_USB_EHCI_TT_NEWSCHED, but I tried to clean things up > last night and mumble. I guess it helps but not as much as I > though. Mumble. It may be the hub-hub case that doesn't > work. I've got a 7 port hub which is really > 2 4 port hubs chained. > > I haven't noticed any troubles without the hub. I'm not > doing anything fancy. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.