1.\" 2.\" $FreeBSD: src/share/man/man4/keyboard.4,v 1.19.2.5 2001/08/17 13:08:38 ru Exp $ 3.\" 4.Dd January 8, 1995 5.Dt KEYBOARD 4 6.Os 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 62.Dv PIO_KEYMAP 63ioctl call, that 64takes a structure keymap_t as argument. 65The layout of this structure is as 66follows: 67.Bd -literal -offset indent 68 struct keymap { 69 u_short n_keys; 70 struct key_t { 71 u_char map[NUM_STATES]; 72 u_char spcl; 73 u_char flgs; 74 } key[NUM_KEYS]; 75 }; 76.Ed 77.Pp 78The field n_keys tells the system how many keydefinitions (scancodes) 79follows. 80Each scancode is then specified in the key_t substructure. 81.Pp 82Each scancode can be translated to any of 8 different values, depending 83on the shift, control, and alt state. 84These eight possibilities are 85represented by the map array, as shown below: 86.Bd -literal 87 alt 88 scan cntrl alt alt cntrl 89 code base shift cntrl shift alt shift cntrl shift 90 map[n] 0 1 2 3 4 5 6 7 91 ---- ------------------------------------------------------ 92 0x1E 'a' 'A' 0x01 0x01 'a' 'A' 0x01 0x01 93.Ed 94.Pp 95This is the default mapping for the key labelled 'A' which normally has 96scancode 0x1E. The eight states are as shown, giving the 'A' key its 97normal behavior. 98The spcl field is used to give the key "special" treatment, and is 99interpreted as follows. 100Each bit corresponds to one of the states above. 101If the bit is 0 the 102key emits the number defined in the corresponding map[] entry. 103If the bit is 1 the key is "special". This means it does not emit 104anything; instead it changes the "state". That means it is a shift, 105control, alt, lock, switch-screen, function-key or no-op key. 106The bitmap is backwards ie. 7 for base, 6 for shift etc. 107.Pp 108The flgs field defines if the key should react on caps-lock (1), 109num-lock (2), both (3) or ignore both (0). 110.Pp 111The 112.Xr kbdcontrol 1 113utility is used to load such a description into/outof 114the kernel at runtime. 115This makes it possible to change the key 116assignments at runtime, or more important to get 117.Dv ( GIO_KEYMAP 118ioctl) 119the exact key meanings from the kernel (fx. used by the X server). 120.Pp 121The function keys can be programmed using the 122.Dv SETFKEY 123ioctl call. 124.Pp 125This ioctl takes an argument of the type fkeyarg_t: 126.Bd -literal -offset indent 127 struct fkeyarg { 128 u_short keynum; 129 char keydef[MAXFK]; 130 char flen; 131 }; 132.Ed 133.Pp 134The field keynum defines which function key that is programmed. 135The array keydef should contain the new string to be used (MAXFK long), 136and the length should be entered in flen. 137.Pp 138The 139.Dv GETFKEY 140ioctl call works in a similar manner, except it returns 141the current setting of keynum. 142.Pp 143The function keys are numbered like this: 144.Bd -literal -offset indent 145 F1-F12 key 1 - 12 146 Shift F1-F12 key 13 - 24 147 Ctrl F1-F12 key 25 - 36 148 Ctrl+shift F1-F12 key 37 - 48 149 150 Home key 49 151 Up arrow key 50 152 Page Up key 51 153 (keypad) - key 52 154 Left arrow key 53 155 (keypad) 5 key 54 156 Right arrow key 55 157 (keypad) + key 56 158 End key 57 159 Down arrow key 58 160 Page down key 59 161 Insert key 60 162 Delete key 61 163 164 Right window key 62 165 Left window key 63 166 Menu key 64 167.Ed 168.Pp 169The 170.Xr kbdcontrol 1 171utility also allows changing these values at runtime. 172.Sh AUTHORS 173.An S\(/oren Schmidt Aq Mt sos@FreeBSD.org 174