GEARCHECK LAB
Keyboard Lab // Multi-Key Diagnostics

KEYBOARD GHOSTING & ROLLOVER

Hold multiple keys at the same time and see exactly which keydown events reach your browser. Track the highest simultaneous count, test gaming combinations, and look for repeatable missing inputs that may indicate a rollover limitation or ghosting-related matrix conflict.

Live diagnostic

Simultaneous key matrix

KEYBOARD LISTENER READY
Click here, then hold several keys together. The test will highlight browser-visible keydown events. Space and Tab are prevented only while this test area is focused so you can include them in combinations.

How to test keyboard rollover

  1. Click the test area to focus it.
  2. Hold a common game combination such as W + A + Shift + Space.
  3. Confirm that every held key lights up at the same time.
  4. Try larger combinations across different rows of the keyboard.
  5. Repeat any combination that appears to miss a key before concluding there is a limitation.

Ghosting vs rollover

Rollover describes how many simultaneous keys a keyboard can report correctly. Ghosting traditionally refers to matrix behavior where an unintended key appears or a real key is blocked by a particular combination.

Modern keyboards often advertise 6-key rollover (6KRO) or N-key rollover (NKRO), but practical behavior can vary by connection mode, firmware and specific key matrix regions.

What counts as a suspicious result?

If the same physical combination repeatedly produces fewer browser-visible keys than you are holding, that combination may be limited somewhere in the keyboard, firmware, operating system or browser input path.

This page cannot prove a hardware ghosting fault from one missing event. Browser shortcuts, operating-system shortcuts and accessibility features can intercept specific combinations before the page receives them.

Useful gaming combinations to try

  • W + A + Shift + Space
  • W + D + Ctrl + R
  • A + S + D + F + J + K
  • Shift + Ctrl + Alt plus a letter
  • Your real in-game movement + ability + push-to-talk combination

Test the combinations you actually use rather than chasing the largest possible number.

Keyboard ghosting test FAQ

Why does a browser shortcut not appear?

Some key combinations are reserved by the browser or operating system and never reach the webpage. Use alternative combinations before blaming the keyboard.

Does a high simultaneous count prove NKRO?

No. It proves that the tested combination reached the browser. True NKRO claims cover broader matrix behavior and may depend on USB mode or firmware.

Why is the mobile experience limited?

On-screen keyboards usually do not expose physical-key behavior the same way. This diagnostic is intended for a physical keyboard.