keyboard ghosting test
If your character stops jumping while you walk diagonally, or a four-key shortcut never fires, the keyboard may be dropping keys. This page opens the rollover test ready to use: click Start, hold as many keys as you can and watch the registered peak.
Typical sign of 6KRO mode. Look for an NKRO mode on the keyboard or use the cable instead of the wireless receiver.
If other groups of 5 keys work, the failure belongs to that combination in the matrix (ghosting or masking).
Rollover is a keyboard's ability to report several pressed keys at once. N-key rollover (NKRO) means any number of keys is registered independently. 6KRO means up to six regular keys (plus the modifier keys) are reported together.
No. The test runs in the browser and only reads the keyboard after you click Start. No key is sent or stored.
Yes. The test reads the physical key position and the visual keyboard has ANSI, ISO and ABNT2 layouts so you can follow the lit keys.
Laptop keyboards often have a matrix without a diode on every key, so certain combinations of 3 or more keys suffer ghosting more easily than on a mechanical gaming keyboard.
The browser only sees what the operating system hands it. If a key goes missing it may be a hardware rollover limit or ghosting in the keyboard matrix, and software cannot tell the two apart. The "apparent limit" is just the most keys that arrived together.