N-Key Rollover (NKRO) & Simultaneous Key Matrix Benchmark
Verify 6KRO vs NKRO simultaneous key press limits on your physical keyboard. Test USB HID report protocols and key blocking diode matrix limits.
Universal Keyboard Diagnostic Suite
Multi-layout visual key tester, switch chatter bounce analyzer, NKRO gaming combo stress tester & APM counter.
Frequently Asked Questions (N-Key Rollover (NKRO) & Simultaneous Key Matrix Benchmark)
10-Item Technical FAQ & USB HID Diagnostic Troubleshooting
What is N-Key Rollover (NKRO)?
NKRO allows every key on the keyboard to be pressed simultaneously without key blocking, dropping, or ghosting.
What is 6KRO (6-Key Rollover)?
6KRO restricts USB HID reports to 6 concurrent alphanumeric keys plus modifier keys (Ctrl, Shift, Alt, Cmd).
What is keyboard ghosting?
Ghosting occurs on cheap membrane keyboards when pressing 3 adjacent keys causes an unpressed 4th key to falsely trigger.
How do diodes enable NKRO in mechanical keyboards?
Individual diodes placed on every switch circuit prevent electrical current from backflowing across grid traces.
How do I perform an NKRO rollover test?
Press both palms down across your keyboard matrix; the counter records total simultaneous registered keys.
Why do some USB keyboards require pressing a shortcut to enable NKRO?
Some keyboards default to 6KRO for legacy BIOS compatibility; press Fn+N or Fn+F12 to switch to USB NKRO mode.
Does USB protocol natively support NKRO?
Standard USB HID boot protocol limits reports to 6KRO; NKRO keyboards use custom report descriptors or virtual hub endpoints.
Is NKRO necessary for rhythm games like Osu! or IIDX?
Yes, rhythm games require simultaneous multi-key chords; 6KRO can cause dropped inputs during dense note patterns.
Can Bluetooth keyboards support full NKRO?
Most Bluetooth HID profiles cap simultaneous key reports at 6KRO to conserve wireless bandwidth and power.
How do I export my NKRO rollover test score?
Click 'Download Certificate' to export a cryptographically signed report certifying your keyboard's peak NKRO count.