« previous next »
Pages:  [1]     Go Down

Author Topic: KRO and USB 2.0 vs 3.0  (Read 2460 times)

0 Members and 1 Guest are viewing this topic.

Offline roknir

  • Thread Starter
  • Posts: 16
KRO and USB 2.0 vs 3.0
« on: Thu, 23 February 2012, 12:28:43 »
As I understand it, if a keyboard uses USB 2.0, no rollover better than 6KRO can be achieved, while PS/2 can have true NKRO.  With USB 3.0 becoming more popular, is the limitation going to be the same?  Will USB 3.0 be limited to 6KRO also or could it do NKRO?
Logged

Offline stingrae

  • Posts: 267
KRO and USB 2.0 vs 3.0
« Reply #1 on: Thu, 23 February 2012, 13:46:22 »
Quote from: roknir;523245
As I understand it, if a keyboard uses USB 2.0, no rollover better than 6KRO can be achieved, while PS/2 can have true NKRO.  With USB 3.0 becoming more popular, is the limitation going to be the same?  Will USB 3.0 be limited to 6KRO also or could it do NKRO?


USB works on polling devices while ps/2 works on well accepting input when it occurs, the behaviour of usb hasnt changed only the bandwidth (afaik, I may be wrong though). Btw you get over 12 kro on some keyboards without emulating keyboards.
Logged
Filco Ninja Tenkeyless  -Noppoo Choc Mini - Cm Storm Quickfire Rapid

Offline alaricljs

  • I be WOT'ing all day...
  • ** Moderator Emeritus
  • Posts: 3715
  • Location: NE US
KRO and USB 2.0 vs 3.0
« Reply #2 on: Thu, 23 February 2012, 13:59:58 »
Not to mention on teensy KB controllers there's working NKRO on USB.
Logged
Filco w/ Imsto thick PBT
Ducky 1087XM PCB+Plate, w/ Matias "Quiet Click" spring-swapped w/ XM Greens

Offline daniel0731ex

  • Posts: 69
KRO and USB 2.0 vs 3.0
« Reply #3 on: Thu, 23 February 2012, 15:14:05 »
I thought the 3.0 was a complete makeover in the internal design.
Logged
"I hated the Blackwidow. Hated, hated, hated, hated, hated the Blackwidow. Hated it. Hated every cheapening feeble useless user-insulting gimmicks of it. Hated the keycap font that thought anyone would like it. Hated the marketing pretense to the keyboard by its belief that anyone would be impressed by it."

Roger Exbert - The Number One Keyboard Critic On The Planet.

Offline stingrae

  • Posts: 267
KRO and USB 2.0 vs 3.0
« Reply #4 on: Thu, 23 February 2012, 15:55:45 »
Quote from: daniel0731ex;523425
I thought the 3.0 was a complete makeover in the internal design.


Yes but not necessarily the way it works in an OS...

The issue with rollover by usb has never been a transfer speed issue afaik. I dont think its possible to poll more actions than 6 unless trickery (ducky or noppoo) or clever electronics (leopold 21 kro).
Logged
Filco Ninja Tenkeyless  -Noppoo Choc Mini - Cm Storm Quickfire Rapid

Offline Soarer

  • * Elevated Elder
  • Posts: 1918
  • Location: UK
KRO and USB 2.0 vs 3.0
« Reply #5 on: Thu, 23 February 2012, 18:44:58 »
Well there won't be any USB 3.0 keyboards, so that question is moot!

I'm not even sure that any are even using full-speed USB; almost all, if not all, are low-speed devices.

Low-speed is tricky to do more than 6KRO, mainly because a packet is limited to 8 bytes. A report can be larger than a packet, or tricks with multiple endpoints (e.g. pretending to be more than one keyboard) can be used, but history tells us these aren't easy to make 100% compatible.

Teensy-based mods use full-speed, so have more freedom. My converter uses a 23 byte report - big enough to have one bit for each useful keyboard HID code (all 172 of them!). And then it's not a big problem to make NKRO 100% compatible.
Logged
Pages:  [1]     Go Up
« previous next »