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Ask Slashdot: Low-Latency PS2/USB Gaming Keyboards?

timothy posted 1 year,17 days | from the edge-of-the-edge-cases dept.

Input Devices 177

An anonymous reader writes "I've a cheap but low latency mouse (A4Tech) and I noticed my trusty old wired Logitech PS/2 keyboard seems at least 50ms slower (if not more) than the mouse when I test with those reaction time sites. I even increased finger travel distance over my mouse button to make it fairer and the difference still remains. So either the tests are slower with keyboards or my keyboard is high latency. Assuming the latter any suggestions for a good reasonably priced gaming keyboard? Extra function keys might be nice but since my hands aren't big what would be better is being able to output a custom key/combo if you hold down (special?) keys while pressing another key. For example I could configure it so if I hold down "Special Key 1" with pinkie or thumb and press 4 it actually outputs 9, and if I hold down shift as well it outputs shift+9 (and not just 9). Being able to replace the capslock key function and have it behave as another key (or a special modifier) would be a bonus — I've never needed capslock and have probably used it more by mistake than for its normal function, or to test how badly a PC has hung."

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FIRST! (-1)

Anonymous Coward | 1 year,17 days | (#44270923)


(Really fast post from my wireless keyboard!)

You're testing wrong (5, Interesting)

guruevi (827432) | 1 year,17 days | (#44270941)

There is not a single modern keyboard that has 50ms latency. You (humans) have that sort of latency.

As far as response times, all you need to do is increase the poll time on the USB stack, you should be able to set it to ~1-5ms, most keyboards are in the 5-10ms range. You can also get a custom keyboard which is used for psychophysics, they run about $300 and have a guaranteed sub-ms latency. But there must be some firmwares out there that can achieve the same for cheaper. I've tested Arduino Leonardo to about 1-2ms latency (also for psychophysics experiments).

Re:You're testing wrong (0)

Anonymous Coward | 1 year,17 days | (#44270947)

Odd, that's about the time it takes to debounce a switch input.

Re:You're testing wrong (0)

Anonymous Coward | 1 year,17 days | (#44271021)

debounce done right shouldn't add latency

Re:You're testing wrong (1)

guruevi (827432) | 1 year,17 days | (#44271227)

Debounce doesn't add latency per se, you only have to trigger your interrupt on the first transition (given the transition is maintained long enough for the processor to pick up) and who cares if it bounces after that.

Also, in psychophysics, most likely you already know when the decision is being made (either EEG or fMRI), the buttons and the display refresh signal are only there to confirm that you should select data in between those time stamps.

Re:You're testing wrong (2)

arielCo (995647) | 1 year,17 days | (#44272159)

I saw a TV program about that once; somehow the results of the experiment could be interpreted to cast doubt on what constitutes free will, but I can't find anything else about it. Do you know a few keywords I could use? A link would be superb.

Re:You're testing wrong (3, Informative)

mt42 (1906902) | 1 year,17 days | (#44272757)

The paper that comes to my mind when I read your post is:

Soon, C. S.; Brass, M.; Heinze, H.-J. & Haynes, J.-D. (2008). Unconscious determinants of free decisions in the human brain. Nature Neuroscience, 11, 5, 543-545, doi:10.1038/nn.2112 [] (article paywalled but a quick google provides an alternative link to the article PDF [] ).

I've a small collection of references for scientific "mind reading" studies I've gathered over the years, so if it's not the one you're thinking of, give me some more details and I might be able to dig it up for you.

Re:You're testing wrong (1)

Darinbob (1142669) | 1 year,17 days | (#44272093)

1ms is also the minimum poll time possible, as it was never designed for low latency. To get lower than that you have to get away from USB.

Re:You're testing wrong (2)

bwoneill (1973028) | 1 year,17 days | (#44271041)

Actually, PS/2 keyboards can't have a latency less than about 50 ms. The PS/2 specification requires a clock speed between 10 and 16.7 kHz which means that the signal must be in the up or down state for 30-50 ms. []

Re:You're testing wrong (3, Informative)

Blaskowicz (634489) | 1 year,17 days | (#44271101)

You're off by a factor of one thousand. What you're quoting says :

Data sent from the device to the host is read on the falling edge of the clock signal; data sent from the host to the device is read on the rising edge. The clock frequency must be in the range 10 - 16.7 kHz. This means clock must be high for 30 - 50 microseconds and low for 30 - 50 microseconds.. If you're designing a keyboard, mouse, or host emulator, you should modify/sample the Data line in the middle of each cell. I.e. 15 - 25 microseconds after the appropriate clock transition. Again, the keyboard/mouse always generates the clock signal, but the host always has ultimate control over communication.

Re:You're testing wrong (1)

Anonymous Coward | 1 year,17 days | (#44271859)

Not exactly a factor of a thousand as the data is serial, and 1 bit isn't the full keyboard code. So you are already more like a factor of 10 off.

Then is also latency of the 8049 core in the chipset etc.
And depending on the multi-byte (1-3) sequence being sent (make/break)

Lesson of the day: If you WANT to say someone is wrong, at least you should verify your own fact first.

Re:You're testing wrong (0)

Anonymous Coward | 1 year,17 days | (#44271149)

You seem to be confusing milliseconds (ms) with microseconds (us). The site you linked is very informative, but almost all the times relating to data transfer are given in microseconds. It even explicitly says the time to transfer a data packet must occur in under 2ms or the host should generate an error.

Re:You're testing wrong (3, Interesting)

AmiMoJo (196126) | 1 year,17 days | (#44271873)

Every keyboard I have ever seen is a USB 1.1 HID device. The maximum polling rate is 10ms in the spec, although some might work at higher frequencies. In any case you are correct, the latency of pretty much any keyboard will be max 10ms. If the test sites say there is more then it isn't the keyboard, it is something in the OS or the browser or the operator.

Re:You're testing wrong (4, Informative)

mc6809e (214243) | 1 year,17 days | (#44271915)

There is not a single modern keyboard that has 50ms latency. You (humans) have that sort of latency.

As far as response times, all you need to do is increase the poll time on the USB stack,

Polling the USB stack has almost nothing to do keyboard response time.

Keyboard response time depends mostly on how often the built-in microcontroller scans the keyboard matrix. A common interval is 40 ms. Polling the USB stack does nothing to get the microcontroller to scan the keyboard matrix more frequently. If the writer of the firmware decides 40 ms between scans is frequent enough, then you're stuck with 39+ ms latency in the worst case.

so this...... (1, Insightful)

spire3661 (1038968) | 1 year,17 days | (#44270949)

So this is how far Slashdot has sunk. Keyboard latency? Fuck the submitter and the mod who approved it.

Re:so this...... (5, Insightful)

dyingtolive (1393037) | 1 year,17 days | (#44270987)

At least it's a nice change from the "do my job for me" Ask Slashdots.

Re:so this...... (1)

Ian A. Shill (2791091) | 1 year,17 days | (#44271669)

I'd like to know what this has to do with SQL.

At least it's a nice change from the "do my job for me" Ask Slashdots.

Re:so this...... (0)

aglider (2435074) | 1 year,17 days | (#44271081)

I'd like to mod you higher than 5.

Re:so this...... (-1, Flamebait)

gl4ss (559668) | 1 year,17 days | (#44271563)

and the guy is using a fucking ps/2 keyboard. you know what the whole submission tells as a whole? he's a fucking device sportsman.

the right answer is this : "YOU SUCK IN GUAGE, LEARN TO PLAY NOOB! it's not the latency that's the problem but your shitty tactics! stop trying to justify losing due to latency!"

oh and if you're posting an ask slashdot surely you should be familiar with the term keyboard macros which would sort out the keycombos.. unless you're worried that they add 1ms to your sniper on/off combo.

Re:so this...... (1)

Mashiki (184564) | 1 year,17 days | (#44271607)

Enjoying that new "buyout" from the bottom feeding trough? I though so.

Re:so this...... (4, Insightful)

Trogre (513942) | 1 year,17 days | (#44272091)

Why the hatred? This seems a genuinely interesting topic to us nerds, whom this site is ostensibly meant to be for.

As far as Ask Slashdot questions go, this is one of the better ones.

Re:so this...... (1)

Luckyo (1726890) | 1 year,17 days | (#44272367)

It is not. The question is "what snake oil should I buy to make me think keyboard will have lower latency".

The current keyboard latency is SIGNIFICANTLY below HUMAN latency. There is simply no way for our nervous system to match it for reason of slowness of electric signal inside our own nerve system.

Re:so this...... (3, Informative)

Twinbee (767046) | 1 year,17 days | (#44272607)

You're missing the point. It still adds ON TOP of what would be standard human latency. Given say, a game where milliseconds matter and can make you lose points, this is an issue.

Re:so this...... (1)

Twinbee (767046) | 1 year,17 days | (#44272625)

Seriously, latency is underrated massively by everyone - what's your problem? One big example is the iPhone 4S. Pressing the home button introduces a terrible half sec lag.

Re:so this...... (1)

Jack Greenbaum (7020) | 1 year,17 days | (#44272953)

Where are my mod points when I need them? Mod it up to 11.

Talk with God (-1)

Anonymous Coward | 1 year,17 days | (#44270957)

Do an offering. Pig fuglly bitch.

God says...
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envenomed whichsoever considereth discovereth plainly
elect liberal cloud unconsciously seven Send hands warranted
king endeavours

50 ms? (1, Insightful)

hammeraxe (1635169) | 1 year,17 days | (#44270989)

Surely 50 ms is just human response time. I highly doubt a "low-latency keyboard" (even if such a thing exists) could improve your gaming performance...

Re:50 ms? (1)

angel'o'sphere (80593) | 1 year,17 days | (#44271027)

The typical human reaction time is between 1/10th and 3/10th (more the later) of a second. That is 100 to 300ms. Officially when you have to learn that shit for driving licenses etc. the official claim is 3/10th and many people who test themselves come down to 2/10th. People in the range of 1/10th are super rare. 50ms how ever is HALF of 1/10th of a second, or in other words 1/20th. Perhaps one of 10,000 has a reaction time so fast, I would say far less than 1 of 10,000 has it.

Re:50 ms? (0)

Anonymous Coward | 1 year,17 days | (#44271059)

For driving tests purposes, we were told reaction time is 2/10 or 3/10 if you're expecting something. But when you're just driving along and then something goes wrong, it can easily be up in the 5/10 range.

Re:50 ms? (1)

guruevi (827432) | 1 year,17 days | (#44271245)

500ms is when you process life threatening emergencies, when you have to process something innocuous from your peripheral vision while doing other tasks like driving in heavy traffic, you could be processing a second or longer.

Re:50 ms? (3, Insightful)

Miamicanes (730264) | 1 year,17 days | (#44271243)

> The typical human reaction time is between 1/10th and 3/10th (more the later) of a second. That is 100 to 300ms.

now pile another 50-100ms of USB latency on top, and you've just increased the problem by a non-insignificant factor.

It's not a coincidence people gripe about USB. By traditional embedded-electronics standards, USB fsck'ing SUCKS. It's not a coincidence that there are STILL things you could bitbang with a real EPP/ECP parallel port that are flat-out impossible to do via USB. USB forces you to do your bitbanging at the remote end, and use the USB bus SOLELY for polled bit-shoveling after the fact. Serial ports required manual configuration up front, but once you got them configured... they pretty much worked flawlessly unless the wire had a short or a bad solder connection. Ditto for traditional parallel and ps/2 ports.

I NEVER used to have ps/2 mice just stall and hang on me the way USB mice do under Windows. I've had plenty of times over the past few years when the ps/2 trackpoint on my keyboard worked fine, but the mouse pointer acted like it was frozen if I moved the USB mouse, for periods of 2-5 seconds a couple of times per week.

Re:50 ms? (5, Informative)

Anonymous Coward | 1 year,17 days | (#44271409)

USB latency is nowhere near 50-100ms, more like 1ms for a low-speed/full-speed device (which most HID devices are). a high speed device could be polled at 8*125us.

You'd probably need the lousiest USB controllers and a horrible CPU to get anywhere near what you're describing.

Disclaimer: I've actually worked on USB Host Controller and Device Controller drivers in embedded environments

Re:50 ms? (0)

Anonymous Coward | 1 year,17 days | (#44271711)

USB HID devices CAN be polled at 1ms if the operating system overrides the data in the descriptors, or the USB device's descriptor data are in violation of the standard(IIRC, or at least a recommendation in the standard, I can't recall which), but typically the minimum is going to be 8ms or 10ms for game devices, and higher for keyboards.

The Linux kernel can be hacked fairly easily to reduce the USB HID poll interval:

Re:50 ms? (0)

Anonymous Coward | 1 year,17 days | (#44271723)

But my guess is that for the OS to process the input into a win32 (or X or whatever) message, sending that to the focussed app (in this case, a full fledged browser) which processes the input message, sends it down the stack, into the javascript processor, which then runs a script based on the assigned handler, which performs some checking, and then counts the time between the greent dot becoming visible, and the execution of the callback handler, that surely takes a bunch of milliseconds too, wouldn't it?

On second thought, maybe I should just accept the fact that my reaction times are shit.

Re:50 ms? (1)

AmiMoJo (196126) | 1 year,17 days | (#44271919)

USB HID device minimum polling interval is 10ms, but some devices will work faster than that. You can get it down to 1ms using a non-HID interface though. USB is absolutely fine for low latency input, unless you are talking about extremely accurate clock syncing etc.

There are limitations though. For example it is possible to miss lines on a USB serial port changing if they change faster than the polling rate, since there are no interrupts.

Any additional latency you are seeing is due to the OS, but on Windows even cheap crap devices easily do 10ms. What OS are you seeing 100ms on? I have done a fair bit of work on this in my job, and I'm interesting to know.

Re:50 ms? (1)

Darinbob (1142669) | 1 year,17 days | (#44272125)

For HID devices like mice and keyboards, they will save up the information and transmit it on the next poll. Ie, one poll to a keyboard can return more than one character. A mouse will coalesce the movement into a single position but as I remember it you should still get multiple button events returned on a single poll.

Re:50 ms? (1)

tlambert (566799) | 1 year,17 days | (#44272281)

For HID devices like mice and keyboards, they will save up the information and transmit it on the next poll. Ie, one poll to a keyboard can return more than one character. A mouse will coalesce the movement into a single position but as I remember it you should still get multiple button events returned on a single poll.

You will get multiple button events on a poll when they are different buttons.

The microcontroller firmware that all the companies in China tend to steal back and forth between them tends to only allow one key eventfrom a polling interval, and the controllers are generally clocked slower.

Now a laptop matrix decoder that synthesizes a fake 8042 keyboard controller and mixes Synaptics PS/2 touchpad events with a faked up PS/2 interface from the matrix decode can go a bit faster, depending. For example, we set the debounce down to 6ms on the Chromebook because we had a fast typer, and we gave preference to keyboard events over touchpad events.

Re:50 ms? (1)

Darinbob (1142669) | 1 year,17 days | (#44272107)

USB was designed for very low data rate devices initially (ie, keyboards and mice). Although it has turned into a universal device standard that doesn't mean the design has changed.

But if a USB mouse is stalling, then it's not USB that's causing this and I am dubious it is the USB driver even. It is a shared bus so there maybe other things on USB that are hogging the time (but not for 2 or 3 seconds) so I'd think instead that there's latency in the OS.

Re:50 ms? (1)

Darinbob (1142669) | 1 year,17 days | (#44272095)

But ask every single hardcore gamer and they'll claim that they are a one in a million person with leet skillz. Low latency gaming devices for gamerz are in the same class as gold plated speaker connectors for audiophiles.

Re:50 ms? (1)

Smauler (915644) | 1 year,17 days | (#44272665)

Anything lower than 100ms is illegal in athletics. You react faster than that, you get a false start, and are disqualified.

Re:50 ms? (0)

SeaFox (739806) | 1 year,17 days | (#44271113)

This just in: people who suck at gaming look for excuses for their performance.

Re:50 ms? (0)

Anonymous Coward | 1 year,17 days | (#44271883)

I remember blaming my trombone when I screwed up my part back in high school ...... not that it ever worked.

Re:50 ms? (0)

Anonymous Coward | 1 year,17 days | (#44271193)

He didn't say the response time is 50ms, he said the difference between mouse and keyboard is 50ms. Maybe he's getting 250ms with the mouse and 300ms with the keyboard or something.

Re:50 ms? (0)

Anonymous Coward | 1 year,17 days | (#44271325)

> Surely 50 ms is just human response time.


> keyboard seems at least 50ms slower (if not more) than the mouse when I test with those reaction time sites.

He's saying that the keyboard is 50ms slower than the mouse.
As in:

mouse + him = x
x +50 = keyboard
(mouse + him)+50 = keyboard

He's already in that equation.

Re:50 ms? (0)

Anonymous Coward | 1 year,17 days | (#44271647)

> Surely 50 ms is just human response time.


> keyboard seems at least 50ms slower (if not more) than the mouse when I test with those reaction time sites.

He's saying that the keyboard is 50ms slower than the mouse.
As in:

mouse + him = x
x +50 = keyboard
(mouse + him)+50 = keyboard

He's already in that equation.

You need to remove him from the equation to accurately talk about the latency of the device, that's the whole problem.
And I think he's confusing milliseconds with microseconds.

Re:50 ms? (2, Funny)

Anonymous Coward | 1 year,17 days | (#44271367)

I did some testing in that regard and the most important thing which can completely ruin gaming experience is latency caused by cable length. I would recommend to cut the the length to two feet maximum, replacement by the oxygen-free copper cables is highly desired as it is well known that cheap cables slow down the transport speed of the electrons (any professional audiophile will confirm that). If you are using wireless keyboard, please close all windows as any airflow/drags can cause variations in the response times.

Re:50 ms? (1)

tlambert (566799) | 1 year,17 days | (#44271447)

Surely 50 ms is just human response time. I highly doubt a "low-latency keyboard" (even if such a thing exists) could improve your gaming performance...

The worlds fastest typist, Stella Pajunas-Garnand from Chicago, clocked in at 216 WPM, which is 1080 CPM, which is 18 CPS, which is in that ballpark.

However, burst rates can go much higher, and if you are doing something like playing a twitch shooter, which is kind of like being a meth-head, then adjacent keystrokes on the same key can be much faster, particularly if you hare hitting the key multiple times within the debounce window, and want to do that because you haven't set your auto repeat rate low enough, so that was the game playing style you trained yourself into as a result.

When working on the Samsung Chromebooks, we had a Director who would consistently outpace the keyboard controller, and we had to reverse engineer what he was doing that caused this, and then we had to have Samsung do firmware changes. His issue was that he was dropping the next key down before releasing the previous key, which tended to result in doubled characters for the first key. He was a very fast burst rate typist.

Personally, optimizing keyboards for twitch shooter doesn't strike me as a terrifically productive use of time, whereas optimizing them for a multiple keys down simultaneously has real world utility for non-meth-heads.

Re:50 ms? (1)

unrtst (777550) | 1 year,17 days | (#44272261)

His issue was that he was dropping the next key down before releasing the previous key, which tended to result in doubled characters for the first key. He was a very fast burst rate typist.

This is a good read related to that:,2955-5.html []

USB has technical limitations on N-key-rollover. Some are limited to only 2 simultanious key presses, some 3, some 6.
PS/2 can technically handle unlimited simultanious key presses, and there are a variety of keyboards that can make use of that.

Personally, I recommend the Das Keyboard. It supports both USB and PS/2 interfaces, 6KRO in USB and NKRO in PS/2, mechanical key switches (depends on the model, but Cherry MX or Red etc), and very low latency (2-5ms). On the downside, it costs money - significantly more than an average keyboard.

There's lots of other keyboards these days sporting mechanical switches and other rarely-considered features, but if the orig poster wants a quality keyboard that'll last and has low latency, one sure bet is Das Keyboard connected via PS/2. I'm pretty sure the majority of keyboards that go for more than $20 would be fine, and any with the mechanical switches would almost certainly perform well enough, but this is the only model of fancy keyboard I've tested and can thus recommend.

Re:50 ms? (1)

ahabswhale (1189519) | 1 year,17 days | (#44271637)

You're obviously not a twitch gamer. Sometimes it's about being 1 ms faster than the other guy. Obviously there are other factors that come into play (like your connection latency) but it all adds up.

Re:50 ms? (0)

Anonymous Coward | 1 year,17 days | (#44271749)

If 1ms is the only difference between your victory and your defeat, you're doing very badly at the game. Positioning, resource control, predicting your enemy's actions, etc. are key. Unless you're including some crap like CoD in your definition of twitch, in which case, go nuts.

he lost already and browser explains (1)

gl4ss (559668) | 1 year,17 days | (#44271867)

You're obviously not a twitch gamer. Sometimes it's about being 1 ms faster than the other guy. Obviously there are other factors that come into play (like your connection latency) but it all adds up.

then you lost already if it's about 1ms.. connection latency goes up and down by that anyways, but that doesn't necessarily matter, depends on how the game handles it's network compensation logic.

some people keep using any lag anywhere as an excuse though and provide an ample market for hifi gaming gear.. doesn't make them better at guessing where the pointer should be at and where the other guy is moving. the guys who go this route never seem to make it to top end though. they just keep fiddling forever.

as long as you don't have a shitty wireless setup you're as good as golden. some wireless setups have horrible latencies but they become apparent without special testing.

however, using a reaction site written in javascript for testing the difference is stupid though fwiw my chrome and wireless setup gives me about the same for mouse and keyboard. smack middle of average reaction time stats for people as measured with dedicated equipment, so I don't think there's too much of lag going on with my setup. however I would wager that some browsers do keyboard events to javascript at different speed than mouse events..

Re:he lost already and browser explains (2)

ahabswhale (1189519) | 1 year,17 days | (#44272649)

Jesus you take things way too literally. First off, I said that 1 ms can make the difference between a win and a loss. That's a fact. It doesn't mean I sit there and do everything I can to try and shave 1 ms off of my latency. I go for most bang for the buck first. Yes, skill is the most important thing but if you're 30 ms slower than me on ping, I will rape you in an FPS. I know this because I used to compete with a clan in UT2k4. 30 ms is FOREVER is twitch gaming. So please spare me the patronizing attitude.

Re:50 ms? (0)

Anonymous Coward | 1 year,17 days | (#44272137)

DELTA you slack cunt.

Re:50 ms? (0)

Anonymous Coward | 1 year,17 days | (#44272955)

Surely 50 ms is just human response time. I highly doubt a "low-latency keyboard" (even if such a thing exists) could improve your gaming performance...

You don't have any basis to know what the latency in this person's keyboard is. Take a look at the writings of John Carmack on the topic of latency. A LOT of hardware being built today unnecessarily adds not just bad latency but absolutely ridiculous latency. Sometimes it's a driver problem and not the hardware. If someone told me that they had a 100ms or 200ms latency keyboard then I wouldn't be surprised that you could buy such a thing. To put things in perspective, you're at a significant disadvantage in online FPS games if your network latency is much worse than 200 ms. Of course, network latency gets added to all the other latencies, so a 100ms latency keyboard is definitely bad news. I guarantee you that shaving 100ms off your computer's latency is MUCH easier than shaving 100ms off your own latency (reaction time), since human reaction time is the range 150ms - 300ms. Part of doing that is getting a keyboard with a good latency.

And you've controlled all the other latency... (1)

maddog42 (208510) | 1 year,17 days | (#44271007)

... to make this an important consideration?

Mouse is 50 ms better at the same test (1)

tepples (727027) | 1 year,17 days | (#44271623)

Mouse is 50 ms better at the same test than keyboard. This means either the keyboard or the operating system's keyboard processing is at fault.

Re: Mouse is 50 ms better at the same test (1)

O('_')O_Bush (1162487) | 1 year,17 days | (#44271653)

Or it takes you 50ms longer to press a key than it does to click a mouse, which has nothing to do with keyboard latency, and everything to do with key travel, force, and how fast your fingers are (rather than his soon you can move them).

Apple keys have hardly any travel (1)

tepples (727027) | 1 year,17 days | (#44271849)

I have a 60 fps camcorder. If key travel took 3 frames to press a key, I'd be able to test that. Besides, I also own an Apple keyboard (from the "mighty" era), and Apple keys have hardly any travel.

Does ultra low-latency really matter? (1)

Arakageeta (671142) | 1 year,17 days | (#44271045)

I am very skeptical of the marketing claims of low-latency human input devices like gaming mice and keyboards. I understand the usefulness of special device configuration (e.g., macro buttons), but does a mouse really need to be polled every 1ms (like Razer mice)? In driving tests, the reaction time of a prepared driver is on the order of 750 to 1000ms ( --- sorry for the paywall). Obviously, driving is not gaming, but let's suppose a gaming reaction time is half this: 375ms to 500ms. Let's compare two mice: one polls at 1ms and the other polls at 10ms. With a base reaction time of 375ms, the resulting difference is about 3% at worst, 2% at best. Is low-latency input devices where we should be optimizing a player's performance? Does it really matter all that much? Wouldn't it be better to focus on things such as network latency and possibly even OS schedulers?

I admit, I am not a serious gamer and I don't invest heavily in gaming equipment. I would be very interested in hearing objective opinion from a gamer. Does an input latency 10ms really matter? If so, do you have objective data that can rule out the placebo effect?

Re:Does ultra low-latency really matter? (0)

Anonymous Coward | 1 year,17 days | (#44271153)

People are thinking in terms of latency of reaction, but that's not really the primary factor.

These devices are used to control objects in a simulation, but you want them to feel as real as possible. If I turn a steering wheel in real life, my connection to it is instant. My reaction times might be slow, but once I've reacted, there is no lag at all.

This (for me) is about striving towards that kind of feel in a gaming scenario. Lots of good things come about by squeezing all the different factors at the margins, rather than one big step-change.

Re: Does ultra low-latency really matter? (0)

Anonymous Coward | 1 year,17 days | (#44272525)

How do you know there isn't latency in your power steering system, play in the mechanical linkages, or between the rubber and the road...

You could be chasing after a level of speed or precision that does not exist in the real world, just like what we have in twitch shooters.

Shit, do a sprint and shoot something at 200 yds, try it.

Re:Does ultra low-latency really matter? (0)

Anonymous Coward | 1 year,17 days | (#44271177)

Does it really matter all that much?

Look, it's not considered polite to wear a penis gourd [] , so obsessing over tiny details is the backup option. ;)

Re:Does ultra low-latency really matter? (3, Interesting)

Splab (574204) | 1 year,17 days | (#44271181)

Normal human reaction time is in the 200ms to 300ms range, however, for specific stuff like gaming where we are reacting to known events, we can possibly react faster (sound for instance is keying us way before this, so we start reacting to the event).

Now the 1 MS reaction time for gaming equipment is for precision, if your mouse doesn't stop moving the place where you wanted it to stop moving, it might be off by one or two pixels, which is a huge deal in gaming.

Re: Does ultra low-latency really matter? (0)

Anonymous Coward | 1 year,17 days | (#44272615)

Honestly, good gameplay should not be dependent on the precision of a few pixels in a better than HD resolution screen.

The real world is way too chaotic to simulate it that closely for entertainment, you'd be leaving so many factors out and magnifying a few, that's not "realism".

Good games have liberal amounts of random chance. So does the real world.

Re:Does ultra low-latency really matter? (1)

Blaskowicz (634489) | 1 year,17 days | (#44271231)

On a PS/2 mouse at least, changing the polling time is useful. It defaulted to 40Hz on Windows 9x which was terrible, though the worst of it was making your mouse look choppy in games. So you could change it to 100Hz (Windows XP default) or 200Hz.

Apart of that I'd say shaving a bit of latency is useful, one main application would be playing Counterstrike 1.6 on the net. Network latency is the big offender here and you can always find how playing is easier when you have 60 or 80ms ping instead of 100 or 120ms, and very low ping (lucky WAN, or LAN) is easier still. You get to hit the opponent more often (and vice versa perhaps).
The thing is I doubt high latency keyboards actually exist - unless there are some unfavorable wireless ones, like a bluetooth one where something might go wrong with the keyboard itself, bluetooth adapater or bluetooth stack.

If gaming you should worry about the display anyway : have low or zero input lag, so you need a suitable LCD or CRT ; higher than 60Hz refresh is nice too (but 75Hz LCD fake it, they just drop frames and support the refresh for compatibility only I think). But it's maybe to get a smoother and faster output, and to see more frames showing a bad guy or a rocket rather than strictly about latency.

Probably not, but some changes can matter (4, Insightful)

Sycraft-fu (314770) | 1 year,17 days | (#44271359)

For certain kinds of games, where reaction time is pretty much the be all, end all (like Call of Duty) it does seem like it can make a difference. It isn't that your human reaction time isn't still the biggest thing, but that you make it faster relative to other people and thus gain an advantage. I was, and still am to a degree, skeptical that it matter much but I've tried it and seen results.

So in my case, it was my monitor. I have long used professional screens, at the time it was a NEC 2690WUXi. Nice pro quality IPS screen, fully calibrated for a great image. It runs at 60fps, meaning 16.7ms between images and has about 33.3ms (2 frames) of delay for its image processing time. So basically 50ms from the time the computer sends the data to it, to the beginning of image formation. A few more ms for the image to fully form.

I decided I wanted to see what the 120Hz hype was about, so I bought myself a second monitor, a BenQ XL2420T. It's a cheap TN panel, but very, very fast and has a mode to cut through all processing and lower latency. In 120fps mode you get a frame every 8.3ms, and delay of about 3.4ms until the image start forming, just another 1.5ms until it is complete. So 11.7ms from data to beginning of image formation.

Well I found out two things. One is that you definitely CAN see the difference between 60 and 120 fps. It is actually more noticeable on the desktop, where you have sharp lines and high contrast, but in games too. It is a level of smoothness and fluidity you hadn't seen before.

The other thing is that my performance in Black Ops 2 was quite measurably better playing on the faster monitor. My KDR (kill death ratio, how many times on average you kill another player per time you die) increased by over 0.5, which is a lot. It was just much easier for me to get shots off on people before they could get me.

Now is that all latency? Probably not, the smoother frame rate probably helps too, but it is a difference that is really there. It isn't a case of "Oh you just want you new monitor to be better," or something I have both kinds of monitors and the pro one is what I use 99.9% of the time and for almost all games (I now have a PA301W) because the better colour and image quality is just so worth it. But there is no question for speed sensitive games, the faster display helps me do better.

So how does this apply to mouse and keyboard? I've no idea. I haven't tested it. The keyboard I use is based off of ergonomics, not speed (a Kinesis Freestyle 2, they rock). However perhaps such a thing could help too.

I mean the theory would go like this: Presume you have two people, both with an equal reaction time. Say 500ms if you like. Their computers process and prepare everything for display at the same time. However one guy has a fast screen, and the other a slow screen, like 10ms vs 50ms. Then also one guy has a fast input device, the other guy a slow one, say 1ms vs 10ms. What this means is that the net reaction time, as in the time from the computer saying "This has happened," to the time it receives a response, is 511ms in one case, and 560ms in the other. If you are talking games where a lot of damage is done per shot, that could be enough to make a difference.

I'm not sure that it is worth worry about as much as people do, but I can see how it can make a difference in theory and I was amazed that the fast monitor made as much difference for me as it did. In general though, my recommendation is just stick to games that aren't so twitch based, and use a nicer display.

Latency can have a number of reasons (3, Interesting)

aglider (2435074) | 1 year,17 days | (#44271063)

Mechanical-to-electronic interface is just one. The one you think it's to blame.
Then you have the system interface (the USB and the PS/2).
Then you have the full OS stack with its drivers, event listeners etc.
Then you have the browser technologies (like Javascript stuff) which could react differently to different input classes.
And finally the network latency.
All of them at the same time.
Maybe you are right in blaming the device, but I wouldn't bet a penny on it.

Re:Latency can have a number of reasons (1)

Blaskowicz (634489) | 1 year,17 days | (#44271135)

So, do the test again with MS-DOS human latency measuring software? ;), even if you have to write it yourself.

Re:Latency can have a number of reasons (0)

Anonymous Coward | 1 year,17 days | (#44271365)

thankfully someone understands that it's more than just you, and the keyboard/mouse

Re:Latency can have a number of reasons (1)

Blaskowicz (634489) | 1 year,17 days | (#44271833)

What I fear then is the submitter guy will change keyboard, and find out the situation is entirely the same.

Sialorrhea (0)

Anonymous Coward | 1 year,17 days | (#44271085)

drool on keyboard

The difference is physical reaction. (0)

AuMatar (183847) | 1 year,17 days | (#44271127)

When using the mouse you just click. This is a very fast, almost reflex like movement of your finger. Your finger is moving millimeters of total distance, and the click is registered as soon as it presses down. A keyboard requires your finger to press down further, and the motion to do that is less of a reflex and more a controlled motion.

In short- deal with it, its a difference in how human reflexes work.

Re:The difference is physical reaction. (1)

wagnerrp (1305589) | 1 year,17 days | (#44271477)

No. It's still a reflex. You don't consciously type. You think of some words, your speech center talks to your motor cortex, and it decides where and how to move your fingers to press the necessary buttons. This has all be hard wired over years of typing to happen very quickly. Now, think of individual letters, and their position on the keyboard, and then try to spell out each word. The whole process becomes much slower, because your conscious mind is getting involved in places it really isn't needed and doesn't belong.

Re: The difference is physical reaction. (0)

Anonymous Coward | 1 year,17 days | (#44271689)

Pah! Gamers! Ever thought of playing electric guitar through a USB interface with a Linux RT/Low latency kernel on a tweaked distro? 8 microseconds is piss easy. Singers need a bit less, but it can be done...

Re: The difference is physical reaction. (0)

Anonymous Coward | 1 year,17 days | (#44271699)

Drunk. I meant milliseconds. Sorry.

Key combo issues (2)

TeknoHog (164938) | 1 year,17 days | (#44271175)

I find some old DOS games (emulated) unplayable because some key combinations won't register at all. For example, pressing one arrow key might not work, if another arrow key is already down. This seems to depend on both the keyboard and the motherboard though...

Re:Key combo issues (2)

pedrop357 (681672) | 1 year,17 days | (#44271315)

Sounds like called ghosting and is likely a problem with the keyboard itself or the way the emulator handles keystroke 'translation'.
With the former, you'll see a lot of high end keyboards talk about being '100% ghosting free' or something similar to mean that every key press will be registered no matter how many keys are simultaneously held down. []

Re:Key combo issues (0)

Anonymous Coward | 1 year,17 days | (#44271687)

Most of the "Gaming" keyboards sold nowadays have listed in their features how many keys it can register held down at a time as well a claim to be non (or at least minimally) ghosting.

Re:Key combo issues (1)

Anonymous Coward | 1 year,17 days | (#44272257)

Ran into this problem in Lara Croft and the Guardian of Light game... you have to press multiple wasd keys to get diagonals and meta for jump/shoot, and my keyboard didn't register these if a meta key was pressed so some parts of the game were freaking impossible. Swapped the keyboard and all the sudden the game worked fine. So yeah definitely keyboard can be a problem all by itself.

PS/2 doesn't have latency (0)

Anonymous Coward | 1 year,17 days | (#44271219)

USB has latency because it is poll based. PS/2 in interrupt based and therefore doesn't have latency.

Re:PS/2 doesn't have latency (1)

Anubis IV (1279820) | 1 year,17 days | (#44271591)

PS/2 in interrupt based and therefore doesn't have latency.

That's merely one source of latency. What about the OS stack? The mechanical-to-electronic interface when the key is pressed or button is clicked? Hell, the speed of electricity? There are many sources of latency, of which that is only one. You still have quite a few others to address.

Measure with micrometer.... (1)

Anonymous Coward | 1 year,17 days | (#44271225)

Measure with micrometer, mark with chalk, cut with ax.

It's all about getting an edge over the competitio (1)

Boycott BMG (1147385) | 1 year,17 days | (#44271263)

I don't know what genre of game the submitter plays, but for fighting games, which I play, input latency can mean the difference between winning and losing. 50ms is 3 frames of lag, which means you need to react 3 frames faster to an overhead or throw. This wouldn't be a problem if everyone used the same equipment, ie PlayStation controller, but if someone had a controller that somehow had lower latency than the regular controllers then everyone who wants to compete would flock to it.

Brain Latency (1)

wjcofkc (964165) | 1 year,17 days | (#44271309)

As has been said more than once already, the latency overall lies within you. Perhaps you should try over clocking your brain:

I plan on getting one, and I don't even game -- disclaimer: you can actually build a crude 2 milliamp transcranial stimulator for about ten bucks, but this looks really cool and contains features outside of my ability to design and build circuits.

Cherry MX Brown (2)

PopeRatzo (965947) | 1 year,17 days | (#44271389)

Forget about latency. It's not that big an issue with decent keyboards.

Just get yourself a decent mechanical keyboard with the Cherry MX Brown switches. The Cherry Blue are good for typists, but not for gamers. The Browns are just right for keyboard gaming. Coolermaster makes about the least expensive one that is well-made. About $80 at newegg. Mine is a Ducky, but it was too expensive. The Coolermaster is every bit as good, and $60 cheaper.

Re:Cherry MX Brown (4, Informative)

willy_me (212994) | 1 year,17 days | (#44271545)

Brown is not what you want. They are similar to the "blue" keys but with less noise - I actually own both. There is still a significant distance the key must travel (up then down) to register sequential keystrokes. What you really want are the "red" keys. These keys require only a minimal amount of travel and do not have a noticeable "click" when activated. A pain for typists but it allows gamers to press keys at a very high frequency. The "black" keys are similar but require ~50% more force so they're a bit slower.

But all mechanical keyboards are great at minimizing latency - it is because of the differences between switches and capacitors. The chiclet keyboards work my altering observed capacitance - this requires a controller to continuously scan for key changes and then send the appropriate signals to the host. This takes time and results in the latency the original poster was talking about. Mechanical keyboards are simple switches and are faster to scan. I imagine some mechanical keyboards are even interrupt driven resulting in latency measured in microseconds -- but changes in capacitance can't trigger interrupts.

Re:Cherry MX Brown (1)

PopeRatzo (965947) | 1 year,17 days | (#44271967)

Hey, thanks. I misunderstood what the Cherry Red switches were for.

I'll give my Brown keyboard to my wife to use for work, and I'll order a Red keyboard right away.

Seriously, thank you very much, friend.

Re:Cherry MX Brown (0)

Anonymous Coward | 1 year,17 days | (#44272565)

Chicklet keyboards work by connecting contacts with conductive rubber, kind of 'mechanical';
The way a keyboard is scanned is not related to the construction of the switches.
Touch screens have capacitive keyboards (one of the technologies that is).

Button depth (1)

NonSequor (230139) | 1 year,17 days | (#44271421)

A mouse button has a hair trigger while you have to push a keyboard key down a pretty good bit before it registers a press. On the reaction time test, the margin between keyboard and mouse narrows to about 10-20ms when I try to make sure that I press down on the key as quickly as possible.

Re:Button depth (0)

Anonymous Coward | 1 year,17 days | (#44271663)

I use a Logitech Illuminated Wired Keyboard. It has a low profile which means quicker response time when pressing keys. Unfortunately, it doesn't have any programmable buttons, but it's still a great gaming keyboard.

Re:Button depth (1)

gl4ss (559668) | 1 year,17 days | (#44271877)

I use a Logitech Illuminated Wired Keyboard. It has a low profile which means quicker response time when pressing keys. Unfortunately, it doesn't have any programmable buttons, but it's still a great gaming keyboard.

you can program the buttons on os level.

unless you're using the keyboard on some ps3 converter to play on the ps3 which would totally explain the submission..

Overclock the USB keyboard !!! (0)

Anonymous Coward | 1 year,17 days | (#44271525)

Hi There,

Your problem sounds very familiar. In FreeBSD's moused there is an "-F" option to make non-gamers mice into gamers mice. Some mice don't like this. Possibly the same trick would work for USB keyboards, that by overriding the USB controllers polling rate in software, you will get the key-presses faster. Look for bInterval field as output from lsusb -vvv (Linux) or usbconfig dump_curr_config_desc (FreeBSD) :-)

Caps Lock isn't a hardware issue (1)

chrylis (262281) | 1 year,17 days | (#44272067)

What the system does with the key labeled "Caps Lock" is controlled by the OS, just like all the other keys. Remapping Caps Lock is usually quite easy in any modern system; KDE's Keyboard settings page has options to make it an extra Control or more exotic things like Hyper or Super, and on Windows you can use RemapKey or AutoHotkey.

PS/2 still FTW (1)

Trogre (513942) | 1 year,17 days | (#44272097)

I still keep at least one PS/2 device, either keyboard or mouse, on every computer. Why? Because no BIOS I have ever seen has the capability to wake up a PC from USB events. Presumably this is due to USB controllers not using hardware interrupts (IRQs), instead relying on polling to give some software-emulated interrupts.

It's so much more convenient to be able to hit the space bar or jiggle the mouse to switch the computer on rather than fumbling beneath the desk for a flimsy power button.

Low Latency USB Keyboard (1)

Zephiris (788562) | 1 year,17 days | (#44272187)

I'm only mildly surprised that I didn't see even a single semi-helpful comment yet. Everyone else appears to be bitching about the question, and saying that USB isn't capable of that. It is, of course, with a few caveats. But assuming you're not connecting a HID device to a USB3 port under Linux and expecting it to get better than 125Hz (driver limitation, works fine on Windows), it all works out of the box assuming you have the right connected devices.

A4Tech makes pretty high quality low latency mice, and apparently you have one, but they also have a similar line of keyboards. 1ms response time on both keyboard and mouse, 8-key rollover on keyboard with programmable macro buttons. Try the A4Tech G800V. It's fairly often on sale somewhere.

My only gripe with it is that it has a 'large' enter key and \ is in a funny place. It's well engineered, and not completely over the top like some other 'gaming keyboards' that offer break-off numpad and other weirdness. It's pretty similar to a standard keyboard, merely with the addition of some macro buttons.

Re:Low Latency USB Keyboard (1)

SGT CAPSLOCK (2895395) | 1 year,17 days | (#44272677)

The larger enter key and placement of the backslash that you describe regarding A4Tech's click boxes are part of the "ISO keymap," but the ones you and I prefer are part of the "ANSI keymap". Just thought you'd like to know. :)

FYI- ISO = International Standards Organization ("International Organization for Standardization")
ANSI = "American National Standards Institute"

PS/2 vs USB (1)

SGT CAPSLOCK (2895395) | 1 year,17 days | (#44272631)

I'm not sure if this is truthful, but it's what I've read in the past. I recall long ago that I was researching this exact topic and came to the conclusion that a good keyboard (Ducky, Filco, Das, WASD, etc) plugged into a PS/2 port is the best solution to combat latency. The reasoning was something like - USB acts by polling the device, so you're pretty much stuck with whatever frequency limitations your driver/port/OS provide. But with PS/2, your input is not polled; rather, it calls an interrupt the second data is available. A little-known bonus is that a lot of the cheesy "gaming" keyboards these days (even some of the mechanical ones!) don't allow n-key rollover unless they're plugged in via PS/2 either. But again, I don't really know the truthfulness of this (aside from the n-key rollover thing, which I experienced with keyboards made by non-dedicated keyboard manufacturers). Any insights, comrades?

Re:PS/2 vs USB (1)

Osgeld (1900440) | 1 year,17 days | (#44272687)

yea an interrupt is generated, there is nothing there saying it has to be processed at that exact same moment, it just sits in a buffer until it can be polled by the OS, so whats the difference?

Re:PS/2 vs USB (1)

SGT CAPSLOCK (2895395) | 1 year,17 days | (#44272733)

As long as the event is generated instantaneously when the interrupt is called, which is the case with the Linux atkbd driver at least, it'll make quite a bit of difference. I think you meant "processed" rather than "polled," in which case you can realize instantly that some overhead has been removed from the process, since it goes from "poll, then process" to "just process".

IBM Model M (1)

leandrod (17766) | 1 year,17 days | (#44272789)

Now known as the Unicomp Customizer.

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