3 ms·

The USB HID standard has a limit of 4 keys pressed at once, unless you do fuckery like virtual USB hubs with additional virtual keyboards (which will cause some

by throwaway2048 8y ago

The USB HID standard has a limit of 4 keys pressed at once, unless you do fuckery like virtual USB hubs with additional virtual keyboards (which will cause some things to misbehave) there is no way around this restriction without custom drivers (which are also a nightmare).

ddingus 8y ago
TIL By chance, do you know the limits on real PS/2?
- userbinator 8y ago
  Effectively none --- the keyboard only sends "key X is pressed" and "key X is released" messages. On the other hand, the key matrix design can impose its own limits.
  - ddingus 8y ago
    Cool, thanks.
  - deaddodo 8y ago
    To expound on that: The matrix in most PS/2 keyboards only supports two-key rollover (reliable detection of two keys pressed at once). In the case of three+ keys there is a chance for missed presses and other artifacts.
    - ddingus 8y ago
      Thanks as well.
rasz 8y ago
No, the basic mode has a limit, and most keyboards keep using it due to (lack of) legacy bios support.
JdeBP 8y ago
This has been debunked several times over the years at Hacker News. The standard imposes no such limit; additional HIDs are not required in order to exceed that number of keys; and properly written ordinary HID drivers can handle what is necessary, as it is an ordinary part of the specification to describe the size of the input report and an ordinary part of a driver's operation to decode and process an input report descriptor in order to know how to decode an input report. * https://news.ycombinator.com/item?id=8191260 https://news.ycombinator.com/item?id=8191260 * https://news.ycombinator.com/item?id=7358911 https://news.ycombinator.com/item?id=7358911 * https://news.ycombinator.com/item?id=8478042 https://news.ycombinator.com/item?id=8478042