USB or PS/2 ?

[mini66]

Does it matter which I chose, is there a performance gain from USB or not?

[Computer-Lab in Basement]

If you're talking about NKRO, there is a performance loss by using USB (NKRO only works via PS/2). USB is 6KRO. Both should be adequate for whatever it is you're doing (gaming, typing, whatever...)

It also depends on the keyboard. Make sure you get a keyboard that is labeled as "NKRO" or "6KRO" otherwise there will be a significant performance loss (pretty much everything else is 2KRO).

[mini66]

Thanks, I'm getting a Q-Pad 85. The USB connection is connected to the end of the PS/2 connection? There's not two leads, one for USB and one for PS/2...its all in one lead you just take off the USB bit to use the PS/2 connection. Hope that makes sense

[Hyde]

Well did the converter came with the keyboard?  Because according to their website that model gets "NKRO Over USB" so in that case I'd assume you should just use USB.

BUT if the connector came with the keyboard then maybe it is designed to give you the choice of using PS2.  Keep in mind for keyboards that can switch between USB and PS2 usually have something pre-installed inside the keyboard that allows this function.  So if a keyboard wasn't designed this way and you buy a off market converter then it won't work.

That being said if your computer supports both USB and PS2, then use PS2.  PS2 has NKRO also is interrupt based as oppose to USB poll at 1000 m/s.  So PS2 is actually faster.  A simple test would be set your keyboard to fastest repeat and lowest delay, then you'll notice PS2 responds faster.

Though at the end of the day the difference is small enough so you'll do just fine either way. 

[mini66]

Thank you! Great using the PS/2 connection works out better for me as I don't have many USB connection left on the back of my PC and I may need it in the future. 

[mini66]

Sorry I got it wrong its the its the Q-Pad 80 that has the PS/2 connection!

[dorkvader]

If you're talking about NKRO, there is a performance loss by using USB (NKRO only works via PS/2). USB is 6KRO. Both should be adequate for whatever it is you're doing (gaming, typing, whatever...)

It also depends on the keyboard. Make sure you get a keyboard that is labeled as "NKRO" or "6KRO" otherwise there will be a significant performance loss (pretty much everything else is 2KRO).

USB supports NKRO, but many companies implement it weird.

I generally go for USB and 6KRO, as I don't really need a higher KRO than that, but if you want the absolute best, you can get a keyboard with PS/2 and NKRO, and then convert it to USB NKRO with a teensy and soarer's code.

I also recommend the ID inovations multimode USB adapters which covert PS2 to USB with 6KRO, which is nice. Most other non-DIY PS2 to USB adapters only do 2KRO.

Another reason to consider PS/2 is that most keyboard that support PS/2 nowadays also support USB with a different cable.

[C5Allroad]

If you're talking about NKRO, there is a performance loss by using USB (NKRO only works via PS/2). USB is 6KRO. Both should be adequate for whatever it is you're doing (gaming, typing, whatever...)

It also depends on the keyboard. Make sure you get a keyboard that is labeled as "NKRO" or "6KRO" otherwise there will be a significant performance loss (pretty much everything else is 2KRO).

USB supports NKRO, but many companies implement it weird.

I generally go for USB and 6KRO, as I don't really need a higher KRO than that, but if you want the absolute best, you can get a keyboard with PS/2 and NKRO, and then convert it to USB NKRO with a teensy and soarer's code.

I also recommend the ID inovations multimode USB adapters which covert PS2 to USB with 6KRO, which is nice. Most other non-DIY PS2 to USB adapters only do 2KRO.

Another reason to consider PS/2 is that most keyboard that support PS/2 nowadays also support USB with a different cable.

How does Ducky implement it?

[Linkbane]

If you're talking about NKRO, there is a performance loss by using USB (NKRO only works via PS/2). USB is 6KRO. Both should be adequate for whatever it is you're doing (gaming, typing, whatever...)

That's not accurate today. Many keyboards, including the QFR, QF TK, and Noppoo all have NKRO over USB, for PC. Therefore, getting a PS/2 keyboard doesn't have any feasible advantages (there is no humanly noticeable performance loss), so a USB is probably your best choice.

EDIT: Meant QFR Stealth, the QFR is not NKRO capable.

[Lu_e]

No, they have 6KRO over USB

PS/2 is (UNLIMITED) Key Roll Over (edit; which the qfr is capable of if using the ps2 adapter)

Correct me if im wrong elite. But I know my QFR is only 6kro on usb because ive tested

[Linkbane]

No, they have 6KRO over USB

PS/2 is (UNLIMITED) Key Roll Over (edit; which the qfr is capable of if using the ps2 adapter)

Correct me if im wrong elite. But I know my QFR is only 6kro on usb because ive tested

My bad. I meant the Stealth, my QFR stealth as well as TK are NKRO over USB, which I've tested for fun quite a few times. You are right, I've heard that the QFR has only 6KRO.

[xandr]

I'm not really convinced by the "PS/2 is faster than USB" or actually the relevance of it.

Let's say you type 120wpm - a "word" in that calculation is generally considered to be 5 letters - that would be 600 characters per minute, or 10 characters per second. That would still only be 10Hz - 1/100th of the USB polling rate of 1000Hz.

Maybe I'm missing something here, but I think nobody actually types fast enough for the USB polling rate to become a bottleneck.

[Soarer]

20HZ - each character is a down and an up

A WPM figure is an average, some keys might come much closer together.

Main thing is delay, for gamers. 1000Hz means less delay than 125Hz, and is more comparable to PS/2 (in fact a little quicker).

But most keyboards are still low-speed USB, which means 125Hz max. Never minds the claims (e.g. CM QFR), that's the fact.

[xandr]

Alright, I can see it from a latency perspective, but seriously, 125Hz would still only be 8ms.

Sure, some people will claim they notice the difference between like 4ms and 8ms delay, but in reality most people don't. I do guitar recording over USB where any latency becomes quite apparent when you play a note and hear it delayed, and anything below 10ms latency is practically not noticeable.

[Hyde]

A simple test would be set your keyboard to fastest repeat and lowest delay, then you'll notice PS2 responds faster.

Though at the end of the day the difference is small enough so you'll do just fine either way. 

lol try this out from control panel -> keyboard setting, you'll notice the PS2 start to repeat faster and feels like there's less delay.

Then again I like said it's not that big of a deal I'm just OCD on repeat delay/rates lol.

[Linkbane]

20HZ - each character is a down and an up

A WPM figure is an average, some keys might come much closer together.

Main thing is delay, for gamers. 1000Hz means less delay than 125Hz, and is more comparable to PS/2 (in fact a little quicker).

But most keyboards are still low-speed USB, which means 125Hz max. Never minds the claims (e.g. CM QFR), that's the fact.

It seems as if many keyboards these days have the 1ms polling; the TK apparently does, the QFR S and many 'game keyboard' companies such as Steelseries and Razer have it also. But still, typing at sometimes upwards of 140 wpm, I've never noticed any delay that would impair my typing ability.

[Soarer]

'Seems'? These things need to be measured and confirmed -  you can't trust the vendor's claims! No, I wouldn't say there were 'many' that have the required full-speed USB to support 1ms. There are certainly more that claim 1ms than have it, unfortunately

Clearly low-speed USB is sufficient for typing for, well, pretty much everyone (as long as the firmware doesn't have some defect, it has been known).

For gaming, delays are more important - every ms is an advantage 

[Linkbane]

'Seems'? These things need to be measured and confirmed -  you can't trust the vendor's claims! No, I wouldn't say there were 'many' that have the required full-speed USB to support 1ms. There are certainly more that claim 1ms than have it, unfortunately

Clearly low-speed USB is sufficient for typing for, well, pretty much everyone (as long as the firmware doesn't have some defect, it has been known).

For gaming, delays are more important - every ms is an advantage 

You misunderstand, I have no way of gauging this, I say that many companies advertise it. Calm down and don't jump over my comment when it means something entirely different.
As far as gaming, that's hardly correct. One frame, or 1/60th of a second, is 16.7 milliseconds. Unless a keyboard has ridiculous latency, there's no way that it would cause more than the loss of a small fraction of a frame; if you insist that that has an effect, you are by far the most hardcore and godmode gamer that I'll ever know.

[Soarer]

No you calm down! I wasn't jumping over your comment, rather the fact that vendors sometimes make false claims.

For gaming, what I say is correct. An average keyboard has not only the random 0 to 8ms delay from the USB, but also internal delays from scanning and debouncing etc. Let's say, for the sake of argument, that it averages 9ms (although in fact that would be better than most). That would mean that about half your keypresses are delayed into the next frame. You might still think that insignificant, but I guess it's a bigger effect than you thought. Overall, it might take (ignoring internal delays this time) 8 + 16.7 = 24.7 ms for the game to receive and register the keypress in the worst case, or it might only take microseconds (if the key is pressed just before the USB polls and just before the frame ends) - reducing that variance does help!

In fact, the internal processing delays are usually as or more significant than the USB delays. Namenlos measured some keyboards (PS/2 and USB) a while back and found overall delays of between 30 and 60ms, from key press to OS. He only tried a few that he had available though. I know that can be reduced to about 2ms (I've done it), at which point there really is no point going further. Part of that is cutting the 8ms USB delay down to 1ms.

But that's all a bit of a tangent - I'm not trying to tell you that you need 1ms polling, any more than I would try to tell you that you need a car that does 200mph! But if you want to do a lap quicker than the next guy, it might help

[laffindude]

My bad. I meant the Stealth, my QFR stealth as well as TK are NKRO over USB, which I've tested for fun quite a few times. You are right, I've heard that the QFR has only 6KRO.

I am not seeing anyone else saying Stealth is NKRO over USB. Post a screenshot of aqua key test of you pressing more than 6 keys at the same time and dump the device descriptors.

[Linkbane]

My bad. I meant the Stealth, my QFR stealth as well as TK are NKRO over USB, which I've tested for fun quite a few times. You are right, I've heard that the QFR has only 6KRO.

I am not seeing anyone else saying Stealth is NKRO over USB. Post a screenshot of aqua key test of you pressing more than 6 keys at the same time and dump the device descriptors.

I will try it when I use it again, but I won't be at my house for a few days. I'll post a picture or something if that helps? I know that it has a 6/NKRO function shift over Esc, so I assume that it has NK.