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Ipac Usb Vs, Ps/2
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Tiger-Heli:

--- Quote from: patrickl on June 15, 2004, 08:08:42 am ---Point 2 seems easy to prove and I claim it's proven to be false. At least I have no problem with it. Certainly not that my PC will reset if I press (more than) 6 keys at the same time as I have read in some threads.

--- End quote ---
You either mis-read that, or the person posting in the thread was mis-informed.  What I have heard (from Andy Warne, years ago, actually) was that a USB Keyboard (not I-PAC) will lock up the computer - Blue Screen of Death, usually - if more than six keys are pressed.  This was in the early Win98 days, so it might not happen on other OS's, and/or I would expect the USB keyboard manufacturers to have circuitry to prevent this, much as they block keypresses in PS/2 to prevent ghost inputs.

In the case of the I-PAC, as I stated previously above:

Depending on board revision, there is a limit of 14, 22, or 16 inputs (plus modifiers such as Shift, Alt, and Ctrl) that the I-PAC supports in USB mode, unlimited in PS/2.
patrickl:
Sounds like people are comparing mobo/bios bugs with USB generic problems. Perhaps in some early USB PC's there are problems, but it's not a problem wit USB in general. In reality it just doens't make sense.

As I just edited there is so much gaming hardware (and mice and keyboards) connected over USB. If that really wouldn't work properly there would be storms of complaints. Apart from compatibility issues I don't see how this theoretical problem could really be a problem in the real world. You cannot fill up a USB controller with interrupts gfrom a HID device. Especially not on a USB 2 PC.
Tiger-Heli:

--- Quote from: patrickl on June 15, 2004, 08:52:19 am ---Sounds like people are comparing mobo/bios bugs with USB generic problems. Perhaps in some early USB PC's there are problems, but it's not a problem wit USB in general. In reality it just doens't make sense.

--- End quote ---
No one is comparing them.  In some cases, the USB problems are mobo/bios related in some cases it's just generic USB stuff.  In both instances it's things that happen with USB that you don't see with PS/2.

--- Quote ---As I just edited there is so much gaming hardware (and mice and keyboards) connected over USB. If that really wouldn't work properly there would be storms of complaints. Apart from compatibility issues I don't see how this theoretical problem could really be a problem in the real world. You cannot fill up a USB controller with interrupts gfrom a HID device. Especially not on a USB 2 PC.

--- End quote ---
Scratch the last sentence, as I am almost positive the I-PAC is not USB 2.0 compatible.

Apart from that, we are talking about a specialized use of the USB port.  For example, if your digital camera pauses for a 1/10th of a second in the middle of d/l an image and then resumes and the image comes out okay on the HD, would you notice or care?  Same for a USB HD, Floppy, etc.  Even most PC games and gaming hardware aren't too overly concerned about multiple inputs generated quickly and at a specified instant.  MAME and MAME interfaces ARE concerned about this!
patrickl:

--- Quote from: Tiger-Heli on June 15, 2004, 09:02:55 am ---
--- Quote from: patrickl on June 15, 2004, 08:52:19 am ---As I just edited there is so much gaming hardware (and mice and keyboards) connected over USB. If that really wouldn't work properly there would be storms of complaints.

--- End quote ---
Apart from that, we are talking about a specialized use of the USB port.  For example, if your digital camera pauses for a 1/10th of a second in the middle of d/l an image and then resumes and the image comes out okay on the HD, would you notice or care?  Same for a USB HD, Floppy, etc.  Even most PC games and gaming hardware aren't too overly concerned about multiple inputs generated quickly and at a specified instant.  MAME and MAME interfaces ARE concerned about this!

--- End quote ---
For those you wouldn't care no, but steering wheels, flight yokes, gaming mice would be bothered with the stated problems. For instance Logitech switched over to almost all USB controllers. If USB really was unable to be used for games, surely gamers would complain (and Logitech would just stick to PS/2 only).

I'd also use the same argument as you that MAME cabs are special items. There are generally no USB harddisks, webcams and such connected. Usually only an I-PAC and some controllers like a trackball, a mouse (spinner) or steering wheel. Hardly devices that will generate the enourmous amounts of interrupts that will clog an USB (let alone a PCI) bus. Of course connecting some of these to a single controller will give some lag, but I doubt you could even measure that. The lag will vary between 0 ms and the time it takes to handle an interrupt, but since the chance of a collision is virtually zero I doubt you'll notice.

BTW I'm confussed by your statement that the I-PAC is not being USB 2 compatible. You mean it is USB 1.1 or something and therefore operates at a lower speed than possible for USB 2.0? I used it on USB 2 ports and it did work fine (I didn't check the speed though).
Tiger-Heli:

--- Quote from: patrickl on June 15, 2004, 09:34:25 am ---You mean it is USB 1.1 or something and therefore operates at a lower speed than possible for USB 2.0?

--- End quote ---
Exactly!  USB 2.0 is only an advantage if your devices are made for it (and possibly if your operating system supports it).  Typically a USB 1.0 or 1.1 device will operate in a USB 2.0 port, but at reduced speed, which the I-PAC would be doing in your case.
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