USB vs PS/2 Keyboard: latency, bandwidth -> inputs per second? - Page 2 - Overclock.net - An Overclocking Community

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USB vs PS/2 Keyboard: latency, bandwidth -> inputs per second?

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post #11 of 131 (permalink) Old 10-03-2010, 10:20 AM
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The PS/2 ports are long obsolete garbage, USB is superior in all respects. USB is entirely more than sufficient when it comes to keyboard and mouse activity; and is even fast enough for stuff that needs high speeds, like hard drives, network adapters, audio and video DACs, and external DVDs.

The port only exists these days because people want to keep their venerable old keyboards for new systems, especially when so many new keyboards are so bad from a user point of view.
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post #12 of 131 (permalink) Old 10-03-2010, 10:24 AM
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classic from the days of .. Firewire
Are you calling Mac users classic and outdated? I'd definitely watch my back in dark passages after posts like that. PS/2 users are more tolerant here(since they dont have to care about some inferior keyboard connectors like USB etc).
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post #13 of 131 (permalink) Old 10-03-2010, 11:02 AM
 
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Quote:
Originally Posted by EvanPitts View Post
The PS/2 ports are long obsolete garbage, USB is superior in all respects. USB is entirely more than sufficient when it comes to keyboard and mouse activity; and is even fast enough for stuff that needs high speeds, like hard drives, network adapters, audio and video DACs, and external DVDs.

The port only exists these days because people want to keep their venerable old keyboards for new systems, especially when so many new keyboards are so bad from a user point of view.
Whew. I was beginning to believe I was the only one at OCN that knew that.
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post #14 of 131 (permalink) Old 10-03-2010, 11:08 AM
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Quote:
Originally Posted by EvanPitts View Post
The PS/2 ports are long obsolete garbage, USB is superior in all respects. USB is entirely more than sufficient when it comes to keyboard and mouse activity; and is even fast enough for stuff that needs high speeds, like hard drives, network adapters, audio and video DACs, and external DVDs.

The port only exists these days because people want to keep their venerable old keyboards for new systems, especially when so many new keyboards are so bad from a user point of view.
Do some research please!

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post #15 of 131 (permalink) Old 10-03-2010, 11:32 AM
 
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I thought that's what we were doing? Here's one of my sources of info. Please be specific what research you are looking at.

Anyway I think we reached consensus in this post. The OP went with USB.
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post #16 of 131 (permalink) Old 10-05-2010, 04:50 PM - Thread Starter
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Quote:
The PS/2 ports are long obsolete garbage, USB is superior in all respects.
USB is just a middle part, it's a pipe connecting two ends. More importantly there is keyboard encoder on one end, and there is keyboard controller and buffer at the other end. As many know there are various limitation on keyboard end, such as scanning rate, blocking, ghosting... and also, what is not well known, different devices can utilize USB protocol in different ways, but what is not known at all are limitations on computer end, where USB packets are read by the host OS and stored in keyboard buffer. -- USB is good for that USB disk drive, and such, but for *KEYBOARD* with the default polling rate of 125Hz, then USB obviously sucks.


* Passmark keyboard test
http://www.passmark.com/products/keytest.htm

With this diagnostic software for USB I get minimum of 7-8ms delay between each key, even if I press three or four of them in the same time, for PS/2 this delay is 4-5ms, PS/2 wins there.



Would you like to perform some tests, and perhaps reconsider your misdirected statement?



Quote:
I thought that's what we were doing? Here's one of my sources of info. Please be specific what research you are looking at.

Anyway I think we reached consensus in this post. The OP went with USB.
That source confirms my fears, it says - "USB keyboard is slow".

The bottleneck of processing USB packets and placing them in keyboard buffer is something USB protocol and keyboard encoder can do nothing about, all this depends on Operating System and perhaps legacy support built in hardware, and I am yet to see some proof that polling keyboard 1000 times per second instead of 125 can actually make a difference as to how many keys per second can be stored in keyboard buffer and practically available to software application.


Without performing more tests and finding out actual real world numbers the only consensus I can reach, based on my own devices I tested, is that USB for keyboards/mouse sucks, but I would surely prefer to have more experimental information to make any such conclusion at all.
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post #17 of 131 (permalink) Old 10-05-2010, 05:59 PM
 
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Are you using the same keyboard for both tests?

As I posted before every keyboard has a different scanning rate based on the engineer's firmware setting to makes sure he/she is removing switch debouncing effects.

I'd use that test btw but those suckers want me to pay for it and I'm cheap (my 30 days ran out looooong ago).
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post #18 of 131 (permalink) Old 10-05-2010, 06:09 PM
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Manyak got 6ms on the i-Rocks KR-6230 (USB) in Passmark.

- Christine
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post #19 of 131 (permalink) Old 10-05-2010, 06:11 PM
 
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Most keyboards are set to that 4 to 6 ms range. It's a lost cause to try and measure all this without an oscilloscope.

I think the OP (according to his posts at the other GameDev forum) is using some old keyboard.

Quote:
My USB keyboard is indeed an odd one, it's from old iMac. But still, am I in minority or majority? -- Would you mind doing USB trace test for simultaneous multiple input on your keyboard?
And I was JOKING about the 1000hz Razer polling rate. Gold USB connectors are obviously only good for looks or gamers wouldn't like them. Jeez. Joke.
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post #20 of 131 (permalink) Old 10-05-2010, 06:21 PM
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MOAR GOLD


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