1.\" 2.\" $FreeBSD: src/share/man/man4/keyboard.4,v 1.19.2.5 2001/08/17 13:08:38 ru Exp $ 3.\" $DragonFly: src/share/man/man4/keyboard.4,v 1.5 2008/05/02 02:05:05 swildner Exp $ 4.\" 5.Dd January 8, 1995 6.Dt KEYBOARD 4 7.Os 8.Sh NAME 9.Nm keyboard 10.Nd pc keyboard interface 11.Sh DESCRIPTION 12The PC keyboard is used as the console character input device. 13The keyboard 14is owned by the current virtual console. 15To switch between the virtual consoles use the sequence 16.Ar ALT+Fn , 17which means hold down ALT and press one of the function keys. 18The 19virtual console with the same number as the function key is then 20selected as the current virtual console and given exclusive use of 21the keyboard and display. 22.Pp 23The console allows entering values that are not physically 24present on the keyboard via a special keysequence. 25To use this facility press and hold down ALT, 26then enter a decimal number from 0-255 via the numerical keypad, then 27release ALT. 28The entered value is then used as the ASCII value for one 29character. 30This way it is possible to enter any ASCII value, not present 31on the keyboard. 32The console driver also includes a history function. 33It is activated by 34pressing the scroll-lock key. 35This holds the display, and enables the cursor 36arrows for scrolling up and down through the last scrolled out lines. 37.Pp 38The keyboard is configurable to suit the individual user and the different 39national layout. 40.Pp 41The keys on the keyboard can have any of the following functions: 42.Pp 43.Bl -tag -width "Modifier Key" -compact 44.It "Normal key" 45Enter the ASCII value associated with the key. 46.It "Function key" 47Enter a string of ASCII values. 48.It "Switch Key" 49Switch virtual console. 50.It "Modifier Key" 51Change the meaning of another key. 52.El 53.Pp 54The keyboard is seen as a number of keys numbered from 1 to n. This 55number is often referred to as the "scancode" for a given key. 56The number 57of the key is transmitted as an 8 bit char with bit 7 as 0 when a key is 58pressed, and the number with bit 7 as 1 when released. 59This makes it 60possible to make the mapping of the keys fully configurable. 61.Pp 62The meaning of every key is programmable via the 63.Dv PIO_KEYMAP 64ioctl call, that 65takes a structure keymap_t as argument. 66The layout of this structure is as 67follows: 68.Bd -literal -offset indent 69 struct keymap { 70 u_short n_keys; 71 struct key_t { 72 u_char map[NUM_STATES]; 73 u_char spcl; 74 u_char flgs; 75 } key[NUM_KEYS]; 76 }; 77.Ed 78.Pp 79The field n_keys tells the system how many keydefinitions (scancodes) 80follows. 81Each scancode is then specified in the key_t substructure. 82.Pp 83Each scancode can be translated to any of 8 different values, depending 84on the shift, control, and alt state. 85These eight possibilities are 86represented by the map array, as shown below: 87.Bd -literal 88 alt 89 scan cntrl alt alt cntrl 90 code base shift cntrl shift alt shift cntrl shift 91 map[n] 0 1 2 3 4 5 6 7 92 ---- ------------------------------------------------------ 93 0x1E 'a' 'A' 0x01 0x01 'a' 'A' 0x01 0x01 94.Ed 95.Pp 96This is the default mapping for the key labelled 'A' which normally has 97scancode 0x1E. The eight states are as shown, giving the 'A' key its 98normal behavior. 99The spcl field is used to give the key "special" treatment, and is 100interpreted as follows. 101Each bit corresponds to one of the states above. 102If the bit is 0 the 103key emits the number defined in the corresponding map[] entry. 104If the bit is 1 the key is "special". This means it does not emit 105anything; instead it changes the "state". That means it is a shift, 106control, alt, lock, switch-screen, function-key or no-op key. 107The bitmap is backwards ie. 7 for base, 6 for shift etc. 108.Pp 109The flgs field defines if the key should react on caps-lock (1), 110num-lock (2), both (3) or ignore both (0). 111.Pp 112The 113.Xr kbdcontrol 1 114utility is used to load such a description into/outof 115the kernel at runtime. 116This makes it possible to change the key 117assignments at runtime, or more important to get 118.Dv ( GIO_KEYMAP 119ioctl) 120the exact key meanings from the kernel (fx. used by the X server). 121.Pp 122The function keys can be programmed using the 123.Dv SETFKEY 124ioctl call. 125.Pp 126This ioctl takes an argument of the type fkeyarg_t: 127.Bd -literal -offset indent 128 struct fkeyarg { 129 u_short keynum; 130 char keydef[MAXFK]; 131 char flen; 132 }; 133.Ed 134.Pp 135The field keynum defines which function key that is programmed. 136The array keydef should contain the new string to be used (MAXFK long), 137and the length should be entered in flen. 138.Pp 139The 140.Dv GETFKEY 141ioctl call works in a similar manner, except it returns 142the current setting of keynum. 143.Pp 144The function keys are numbered like this: 145.Bd -literal -offset indent 146 F1-F12 key 1 - 12 147 Shift F1-F12 key 13 - 24 148 Ctrl F1-F12 key 25 - 36 149 Ctrl+shift F1-F12 key 37 - 48 150 151 Home key 49 152 Up arrow key 50 153 Page Up key 51 154 (keypad) - key 52 155 Left arrow key 53 156 (keypad) 5 key 54 157 Right arrow key 55 158 (keypad) + key 56 159 End key 57 160 Down arrow key 58 161 Page down key 59 162 Insert key 60 163 Delete key 61 164 165 Right window key 62 166 Left window key 63 167 Menu key 64 168.Ed 169.Pp 170The 171.Xr kbdcontrol 1 172utility also allows changing these values at runtime. 173.Sh AUTHORS 174.An S\(/oren Schmidt Aq sos@FreeBSD.org 175