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Today most of personal computer is using USB interface as your primary keyboard connection, and some keyboard may use bluetooth wireless connection. Regardless which connection it was used, your operating system will recognize your keyboard as Human Interface Devices (a.k.a. HID) and there are two operating mode, “Boot Protocol” and “Report Protocol”. When your computer boots, your keyboard is registered as Boot Protocol by BIOS (Basic Input/Output System). The limitation of Boot Protocol can only transmit 8-bytes of key press data; 2-bytes are reserved for modified key and reserved key, and 6-bytes are usable to receive your key inputs. Each key press is 1 byte, therefore, 6-key rollover meaning only 6 key press including modified key (for example, Control + C key) can be done at the same time.

When do you use 6-key rollover?

In some situation you have to use 6-key rollover mode otherwise your system will not recognize your key press. For example, in some older computer system, older BIOS, or older operating system.

Tesoro keyboard 6-key rollover can be activated by using FN + Insert key.

N-key rollover

While HID with Boot Protocol can only accept 6 key press at the same time, what happen you are in situation required you to press more than 6 keys at the same time? For example when you are playing games, you need to keep pressing a key for running instead of walking, two keys to move side way (combination of moving forward and moving left/right), switching weapon, shooting key, jumping, and switching camera view all at the same time, one of your action will not be registered. Therefore, HID “Report Protocol” mode must be used between the keyboard and operating system in order to recognize all key presses.

In computer technology 1 byte is 8 bits, and HID Boot Protocol has 8 bytes, total 64 bits data available to use. HID “Report Protocol” remaps all keys and total 64 keys can be reported simultaneously. Report Protocol requires both the keyboard hardware and operating system driver support.

Tesoro keyboard N-key rollover can be activated by using FN + Delete key.

Key jamming and ghosting

Key jamming occurs when combination of three keys pressed simultaneously, fourth key press will register incorrectly. Ghosting is referring on fast typing extra letter is added due to key jamming.