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 1.2 2003/06/17 04:36:59 dillon 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 PIO_KEYMAP ioctl call, that 63takes a structure keymap_t as argument. 64The layout of this structure is as 65follows: 66.Pp 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 (GIO_KEYMAP ioctl) 117the exact key meanings from the kernel (fx. used by the X server). 118.Pp 119The function keys can be programmed using the SETFKEY ioctl call. 120.Pp 121This ioctl takes a argument of the type fkeyarg_t: 122.Bd -literal -offset indent 123 struct fkeyarg { 124 u_short keynum; 125 char keydef[MAXFK]; 126 char flen; 127 }; 128.Ed 129.Pp 130The field keynum defines which function key that is programmed. 131The array keydef should contain the new string to be used (MAXFK long), 132and the length should be entered in flen. 133.Pp 134The GETFKEY ioctl call works in a similar manner, except it returns 135the current setting of keynum. 136.Pp 137The function keys are numbered like this: 138.Bd -literal -offset indent 139 F1-F12 key 1 - 12 140 Shift F1-F12 key 13 - 24 141 Ctrl F1-F12 key 25 - 36 142 Ctrl+shift F1-F12 key 37 - 48 143 144 Home key 49 145 Up arrow key 50 146 Page Up key 51 147 (keypad) - key 52 148 Left arrow key 53 149 (keypad) 5 key 54 150 Right arrow key 55 151 (keypad) + key 56 152 End key 57 153 Down arrow key 58 154 Page down key 59 155 Insert key 60 156 Delete key 61 157 158 Right window key 62 159 Left window key 63 160 Menu key 64 161.Ed 162.Pp 163The 164.Xr kbdcontrol 1 165utility also allows changing these values at runtime. 166.Sh AUTHORS 167.An S\(/oren Schmidt Aq sos@FreeBSD.org 168