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Keyboard Ghosting & Multi-Key Rollover Tester

Test simultaneous multi-key rollover (NKRO) and detect blocked key combinations. Tracks active keydown sets without keyup releases to identify maximum simultaneous keys registered by the keyboard electrical matrix.

N-Key Rollover & Keyboard Ghosting Lab

Peak Concurrent: 0 Keys

Press and hold multiple keys at the exact same moment (e.g. WASD + Shift + Space). Higher peak numbers confirm true N-Key Rollover (NKRO).

Currently Held Keys:
None

Standard Gaming Cluster Rollover Test:

W A S D Shift Space

How to use this test

  1. Press common gaming combinations (e.g. W + A + Shift + Space).
  2. Observe all simultaneously active keys highlighted on the board.
  3. Try pressing 6 or more keys at once across different rows.
  4. Verify whether any key was omitted or falsely pressed.

How to understand your result

Looks good: All simultaneously pressed keys registered cleanly (high NKRO rating).
Check this: Keys failed to register when 3+ specific adjacent keys were held (membrane matrix limit).

Troubleshooting: what to try next

  • Budget membrane keyboards use shared matrix traces that block 3+ simultaneous key presses.
  • Gaming keyboards with N-Key Rollover (NKRO) over USB isolate every switch with a diode.

What this test cannot tell you

Operating system keyboard shortcut combinations may trigger system actions before being captured.

Frequently Asked Questions

EP
Tested & Reviewed by [REAL AUTHOR NAME - OWNER TO COMPLETE]
Last Reviewed: 2026-10-17 • Test Method: Active Set tracking of simultaneous event.code keydown states • How We Test