1.\" 2.\" $FreeBSD$ 3.\" 4.Dd January 8, 1995 5.Dt KEYBOARD 4 6.Os FreeBSD 7.Sh NAME 8.Nm keyboard 9.Nd pc keyboard interface 10.Sh DESCRIPTION 11The PC keyboard is used as the console character input device. 12The keyboard 13is owned by the current virtual console. 14To switch between the virtual consoles use the sequence 15.Ar ALT+Fn , 16which means hold down ALT and press one of the function keys. 17The 18virtual console with the same number as the function key is then 19selected as the current virtual console and given exclusive use of 20the keyboard and display. 21.Pp 22The console allows entering values that are not physically 23present on the keyboard via a special keysequence. 24To use this facility press and hold down ALT, 25then enter a decimal number from 0-255 via the numerical keypad, then 26release ALT. 27The entered value is then used as the ASCII value for one 28character. 29This way it is possible to enter any ASCII value, not present 30on the keyboard. 31The console driver also includes a history function. 32It is activated by 33pressing the scroll-lock key. 34This holds the display, and enables the cursor 35arrows for scrolling up and down through the last scrolled out lines. 36.Pp 37The keyboard is configurable to suit the individual user and the different 38national layout. 39.Pp 40The keys on the keyboard can have any of the following functions: 41.Pp 42.Bl -tag -width "Modifier Key" -compact 43.It "Normal key" 44Enter the ASCII value associated with the key. 45.It "Function key" 46Enter a string of ASCII values. 47.It "Switch Key" 48Switch virtual console. 49.It "Modifier Key" 50Change the meaning of another key. 51.El 52.Pp 53The keyboard is seen as a number of keys numbered from 1 to n. This 54number is often referred to as the "scancode" for a given key. 55The number 56of the key is transmitted as an 8 bit char with bit 7 as 0 when a key is 57pressed, and the number with bit 7 as 1 when released. 58This makes it 59possible to make the mapping of the keys fully configurable. 60.Pp 61The meaning of every key is programmable via the PIO_KEYMAP ioctl call, that 62takes a structure keymap_t as argument. 63The layout of this structure is as 64follows: 65.Pp 66.Bd -literal -offset indent 67 struct keymap { 68 u_short n_keys; 69 struct key_t { 70 u_char map[NUM_STATES]; 71 u_char spcl; 72 u_char flgs; 73 } key[NUM_KEYS]; 74 }; 75.Ed 76.Pp 77The field n_keys tells the system how many keydefinitions (scancodes) 78follows. 79Each scancode is then specified in the key_t substructure. 80.Pp 81Each scancode can be translated to any of 8 different values, depending 82on the shift, control, and alt state. 83These eight possibilities are 84represented by the map array, as shown below: 85.Bd -literal 86 alt 87 scan cntrl alt alt cntrl 88 code base shift cntrl shift alt shift cntrl shift 89 map[n] 0 1 2 3 4 5 6 7 90 ---- ------------------------------------------------------ 91 0x1E 'a' 'A' 0x01 0x01 'a' 'A' 0x01 0x01 92.Ed 93.Pp 94This is the default mapping for the key labelled 'A' which normally has 95scancode 0x1E. The eight states are as shown, giving the 'A' key its 96normal behavior. 97The spcl field is used to give the key "special" treatment, and is 98interpreted as follows. 99Each bit corresponds to one of the states above. 100If the bit is 0 the 101key emits the number defined in the corresponding map[] entry. 102If the bit is 1 the key is "special". This means it does not emit 103anything; instead it changes the "state". That means it is a shift, 104control, alt, lock, switch-screen, function-key or no-op key. 105The bitmap is backwards ie. 7 for base, 6 for shift etc. 106.Pp 107The flgs field defines if the key should react on caps-lock (1), 108num-lock (2), both (3) or ignore both (0). 109.Pp 110The 111.Xr kbdcontrol 1 112utility is used to load such a description into/outof 113the kernel at runtime. 114This makes it possible to change the key 115assignments at runtime, or more important to get (GIO_KEYMAP ioctl) 116the exact key meanings from the kernel (fx. used by the X server). 117.Pp 118The function keys can be programmed using the SETFKEY ioctl call. 119.Pp 120This ioctl takes a argument of the type fkeyarg_t: 121.Bd -literal -offset indent 122 struct fkeyarg { 123 u_short keynum; 124 char keydef[MAXFK]; 125 char flen; 126 }; 127.Ed 128.Pp 129The field keynum defines which function key that is programmed. 130The array keydef should contain the new string to be used (MAXFK long), 131and the length should be entered in flen. 132.Pp 133The GETFKEY ioctl call works in a similar manner, except it returns 134the current setting of keynum. 135.Pp 136The function keys are numbered like this: 137.Bd -literal -offset indent 138 F1-F12 key 1 - 12 139 Shift F1-F12 key 13 - 24 140 Ctrl F1-F12 key 25 - 36 141 Ctrl+shift F1-F12 key 37 - 48 142 143 Home key 49 144 Up arrow key 50 145 Page Up key 51 146 (keypad) - key 52 147 Left arrow key 53 148 (keypad) 5 key 54 149 Right arrow key 55 150 (keypad) + key 56 151 End key 57 152 Down arrow key 58 153 Page down key 59 154 Insert key 60 155 Delete key 61 156 157 Right window key 62 158 Left window key 63 159 Menu key 64 160.Ed 161.Pp 162The 163.Xr kbdcontrol 1 164utility also allows changing these values at runtime. 165.Pp 166.Sh AUTHORS 167.An S\(/oren Schmidt Aq sos@FreeBSD.org 168