Ghosting test that shows every key held at once

Ghosting is a key arriving that you never pressed; blocking is a key you did press failing to arrive. They come from the same place — the grid of rows and columns your switches are wired into — but they are opposite symptoms and only one of them is still common. Ghosting needs a matrix without diodes, where three closed switches forming three corners of a rectangle let current reach the fourth corner and the controller reads a switch nobody touched. Blocking is what manufacturers did about it: rather than report a phantom, the controller refuses the whole ambiguous group, so a key simply goes missing. Nearly every keyboard sold today blocks and does not ghost, which is why this page marks the two differently instead of calling both of them ghosting.

No, six is a specification rather than a defect. The USB keyboard boot protocol — the simple format every BIOS and every bootloader understands, because it has to work before any driver is loaded — sends an eight-byte report with room for exactly six keycodes at a time. A keyboard that stays in that mode reports six and refuses the seventh, and that includes some very expensive boards running with their software features switched off. If you need more, the board has to advertise a report descriptor of its own, which is what the marketing calls NKRO.

Because they are sent as bits rather than as keycodes. That eight-byte report begins with one byte of flags, one bit each for left and right Ctrl, Shift, Alt and the Windows or Command key, and those bits are transmitted whatever else is happening. So even the strictest six-key board will happily hold six letters plus all four of your modifiers at once — ten keys, on hardware that is honestly described as 6KRO. This page counts them on their own line for that reason; a tester that adds them together reports a rollover figure four higher than the keyboard actually has.

Because rollover is not a number of keys, it is a question of where those keys sit in the grid. Two switches on the same row and two on the same column are the ingredients of an ambiguous group, so a combination that happens to be spread across the matrix passes while a tighter one on the same board fails. Shift is free in the first example because it never occupies a keycode slot. This is exactly why the presets on this page are shaped differently from each other: four keys on one number row and four keys scattered across the letters ask completely different questions of the same hardware.

Almost certainly not, and the honest test is the combos you personally hold rather than the number on the box. Six simultaneous keys plus every modifier covers movement, a modifier, a crouch and two abilities at once, which is more than most people press together. Rhythm games and some fighting-game layouts genuinely exceed it, and so does anything where two people share one keyboard. If a combination you actually use drops a key here, that is worth spending money on; if it does not, the upgrade buys you a number rather than an outcome.

Usually it is a lost key-up rather than a ghost. If the window loses focus mid-hold — a notification steals it, or you alt-tab — the release event is delivered somewhere else and the page would show that key held for ever, so the board clears itself whenever focus leaves and restarts the count. A cap that stays lit while this window is still in front of you is different: either the keycap is physically stuck on its stem, or debris is holding the switch closed. Press Clear the record, then press and release that one key on its own to see whether it releases cleanly.

No, and the two share nothing but the word. Keyboard ghosting is a phantom keypress produced by the wiring inside the keyboard. Monitor ghosting is a faint trail behind a moving object, caused by liquid crystal pixels that cannot finish changing color before the next frame arrives. If you came here because something is smearing on screen rather than because keys are going missing, this is the wrong page — the display tests are where that is measured.