How Are ESC, Grave (`) And Tilde (~) Implemented In (some) 60 ...

After remapping my grave-tilde `~ key to its original function for my Keychron K6 on Linux, I coudn't help but wonder how those keys are implemented scancode-wise on 60/65% keyboards. FWIW, on a ANSI layout keyboard, the tilde ~ symbol exist only on the second layer of grave-tilde `~ key (by pressing Shift + `) and this is handled by the operating system. So how do these small-form-factor keyboards manage to enter the ` and ~ with manufactors' choice of modifiers?

In this article I will experiment with the scancodes sent while entering ESC, `, ~ on two 65% keyboards: Keychron K6 and Qisan Magiforce 68.

How does it normally work?

Normally, pressing the `~ key on a keyboard sends scancode 41, signalling the operating system that the ` key has pressed. When on ANSI layout, typing ~ is achieved by pressing Shift + `; operating systems interpret this combo-key and enter a ~ symbol for you.

Keychon K6

The Keychron K6 is a 65% keyboard with bluetooth connectivity. ESC is entered normally; ` and ~ are entered entirely using function keys as modifiers.

Symbol	Key Press(es)
ESC	ESC
`	fn1 + ESC
~	fn2 + ESC

Debugging with evtest

Entering ESC, `, ~ while running evetst gives the following

$ sudo evtest /dev/input/by-id/usb-Keychron_Keychron_K6-event-kbd ... Event: time 1634444664.936753, type 4 (EV_MSC), code 4 (MSC_SCAN), value 70029 Event: time 1634444664.936753, type 1 (EV_KEY), code 1 (KEY_ESC), value 1 Event: time 1634444664.936753, -------------- SYN_REPORT ------------ `Event: time 1634444665.027811, type 4 (EV_MSC), code 4 (MSC_SCAN), value 70029 Event: time 1634444665.027811, type 1 (EV_KEY), code 1 (KEY_ESC), value 0 Event: time 1634444665.027811, -------------- SYN_REPORT ------------ Event: time 1634444667.688758, type 4 (EV_MSC), code 4 (MSC_SCAN), value 70035 Event: time 1634444667.688758, type 1 (EV_KEY), code 41 (KEY_GRAVE), value 1 Event: time 1634444667.688758, -------------- SYN_REPORT ------------ `Event: time 1634444667.779851, type 4 (EV_MSC), code 4 (MSC_SCAN), value 70035 Event: time 1634444667.779851, type 1 (EV_KEY), code 41 (KEY_GRAVE), value 0 Event: time 1634444667.779851, -------------- SYN_REPORT ------------ Event: time 1634444671.726653, type 4 (EV_MSC), code 4 (MSC_SCAN), value 700e1 Event: time 1634444671.726653, type 1 (EV_KEY), code 42 (KEY_LEFTSHIFT), value 1 Event: time 1634444671.726653, type 4 (EV_MSC), code 4 (MSC_SCAN), value 70035 Event: time 1634444671.726653, type 1 (EV_KEY), code 41 (KEY_GRAVE), value 1 Event: time 1634444671.726653, -------------- SYN_REPORT ------------ ~Event: time 1634444671.739657, type 4 (EV_MSC), code 4 (MSC_SCAN), value 700e1 Event: time 1634444671.739657, type 1 (EV_KEY), code 42 (KEY_LEFTSHIFT), value 0 Event: time 1634444671.739657, type 4 (EV_MSC), code 4 (MSC_SCAN), value 70035 Event: time 1634444671.739657, type 1 (EV_KEY), code 41 (KEY_GRAVE), value 0 Event: time 1634444671.739657, -------------- SYN_REPORT ------------

The first half of output snippet is fairly standard. What was interesting is the last final portion: when fn2 + ESC are pressed, the keyboard sends the following key sequence:

Left Shift ON, GRAVE ON, Left Shift OFF, GRAVE OFF.

Essentially, when one presses fn2 + ESC, the Keychron K6 sends a "ghost" Shift key press, immediately followed by the ` key, thereby "tricking" the operating system into thinking that you pressed Shift + ` to type the ~ symbol.

Symbol	Key Press(es)	Keyboard scancodes sent
ESC	ESC	01 ESC
`	fn1 + ESC	41 `
~	fn2 + ESC	42 Left Shift, 41 `

Qisan Magicforce 68

The Qisan Magicforce 68 is a budget 65% keyboard. ESC, `, ~ are entered by:

Symbol	Key Press(es)
ESC	ESC
`	Fn + ESC
~	Shift + ESC

Debugging with evtest

Entering ESC, `, ~ while running evetst gives the following

$ sudo evtest /dev/input/by-id/usb-HOLDCHIP_USB_Gaming_Keyboard-event-kbd ... Event: time 1634446951.832094, type 4 (EV_MSC), code 4 (MSC_SCAN), value 70029 Event: time 1634446951.832094, type 1 (EV_KEY), code 1 (KEY_ESC), value 1 Event: time 1634446951.832094, -------------- SYN_REPORT ------------ `Event: time 1634446951.888008, type 4 (EV_MSC), code 4 (MSC_SCAN), value 70029 Event: time 1634446951.888008, type 1 (EV_KEY), code 1 (KEY_ESC), value 0 Event: time 1634446951.888008, -------------- SYN_REPORT ------------ Event: time 1634446954.473025, type 4 (EV_MSC), code 4 (MSC_SCAN), value 70035 Event: time 1634446954.473025, type 1 (EV_KEY), code 41 (KEY_GRAVE), value 1 Event: time 1634446954.473025, -------------- SYN_REPORT ------------ `Event: time 1634446954.526951, type 4 (EV_MSC), code 4 (MSC_SCAN), value 70035 Event: time 1634446954.526951, type 1 (EV_KEY), code 41 (KEY_GRAVE), value 0 Event: time 1634446954.526951, -------------- SYN_REPORT ------------ Event: time 1634446955.289994, type 4 (EV_MSC), code 4 (MSC_SCAN), value 700e1 Event: time 1634446955.289994, type 1 (EV_KEY), code 42 (KEY_LEFTSHIFT), value 1 Event: time 1634446955.289994, -------------- SYN_REPORT ------------ Event: time 1634446955.421018, type 4 (EV_MSC), code 4 (MSC_SCAN), value 70035 Event: time 1634446955.421018, type 1 (EV_KEY), code 41 (KEY_GRAVE), value 1 Event: time 1634446955.421018, -------------- SYN_REPORT ------------ ~Event: time 1634446955.447924, type 4 (EV_MSC), code 4 (MSC_SCAN), value 700e1 Event: time 1634446955.447924, type 1 (EV_KEY), code 42 (KEY_LEFTSHIFT), value 0 Event: time 1634446955.447924, -------------- SYN_REPORT ------------ Event: time 1634446955.518009, type 4 (EV_MSC), code 4 (MSC_SCAN), value 70035 Event: time 1634446955.518009, type 1 (EV_KEY), code 41 (KEY_GRAVE), value 0 Event: time 1634446955.518009, -------------- SYN_REPORT ------------

As it turns out, and kind of expectedly, the Magiforce 68 uses the same "ghost key press" principle to mimick key presses for ` and ~; the only difference is the key combinations chosen by the manufacturer for triggering such scancodes.

Symbol	Key Press(es)	Keyboard scancodes sent
ESC	ESC	01 ESC
`	Fn + ESC	41 `
~	Shift + ESC	42 Left Shift, 41 `