Quote Originally Posted by mvs_sarma View Post
Hi,

it is a nice and useful observation. Perhaps we have to see whether the front ports are served by a flat cable and not couing up for speed. how ever we are working a t very low speed while programming the PICs or any other devices. it should not matter-- this point is worth analyzing.
Yes, we are working at low speeds, nowhere near even the USB 1.1 limit. The problem is that USB works in packets, it 'saves up' data, then spits it out in bulk and waits 'x' amount of time for a response. It's got nothing to do with the cable (well, ok, 3 strands of wire aren't going to work very well ). If you've got a 'hub' in the middle (like most front USB port setups), it's another millisecond or two of waiting for whatever software is running on Windows. That extra millisecond is what causes some Windows program to dump thinking that the device has disconnected...or something...

You're right...it shouldn't matter. But, like I've said, I've got an iPod Shuffle, Mobiblu Cube, RCA Lyra (all mp3 players), a Warp13a running on a USB-serial converter, a cheap Lexmark printer, a 2.5" USB hard drive case, a Thrustmaster HOTAS Cougar joystick/throttle, and a full setup of CHProducts Virtual Flight Yoke, Pedals, Throttle setup...
I've also got 2 different PC's, one is a cheap, low end Soyo motherboard, the other is a high end Asus type. None of the above mentioned items will work 100% of the time on the front ports and none of them will 'flash upgrade' on the front ports at any time; All of then will work 100% of the time and 'flash upgrade' without problem on the rear ports. And, on my Dell 8200 laptop, everything flash upgrades just fine when plugged directly into the laptop. But as soon as I plug in a USB hub of some type, they fail 99% of the time.

I've duplicated this behavior on a half a dozen computers (prebuilt Dell & Gateway types, home builts, top of the line, bottom of the barrel, etc), neighbors, friends, co-workers, etc. (after awhile it just becomes pointless to test a theory, but ya know, why not).

I don't know if it's Windows XP (although I've tried it using WinME, Win2K, and Win98SE w/ USB patch and they do the same thing) or just some obscure USB driver bug that most manufacturers seem to have...

Beats me... I just know that plugging into the rear (direct motherboard connect) ports always works for me when doing something sensitive like flash upgrading something. For regular use, front ports work fine.