1.\" 2.\" $Id: keyboard.4,v 1.11 1997/03/07 02:49:47 jmg Exp $ 3.\" 4.Dd January 8, 1995 5.Dt KEYBOARD 4 i386 6.Os FreeBSD 7.Sh NAME 8.Nm keyboard 9.Nd pc keyboard interface 10.Sh DESCRIPTION 11 12The PC keyboard is used as the console character input device. The keyboard 13is owned by the current virtual console. 14To switch between the virtual consoles use the sequence 15.Ar ALT+Fn 16, which means hold down ALT and press one of the function keys. The 17virtual console with the same number as the function key is then 18selected as the current virtual console, and given exclusive use of 19the keyboard and display. 20 21The console allows entering values that are not physically 22present on the keyboard via a special keysequence. 23To use this facility press and hold down ALT, 24then enter a decimal number from 0-255 via the numerical keypad, then 25release ALT. The entered value is then used as the ASCII value for one 26character. This way it is possible to enter any ASCII value, not present 27on the keyboard. 28The console driver also includes a history function. It is activated by 29pressing the scroll-lock key. This holds the display, and enables the cursor 30arrows for scrolling up and down through the last scrolled out lines. 31 32The keyboard is configurable to suit the individual user and the different 33national layout. 34 35The keys on the keyboard can have any of the following functions: 36 37 Normal key - Enter the ASCII value associated with the key. 38 39 Function key - Enter a string of ASCII values. 40 41 Switch Key - Switch virtual console. 42 43 Modifier Key - Change the meaning of another key. 44 45 46The keyboard is seen as a number of keys numbered from 1 to n. This 47number is often referred to as the "scancode" for a given key. The number 48of the key is transmitted as an 8 bit char with bit 7 as 0 when a key is 49pressed, and the number with bit 7 as 1 when released. This makes it 50possible to make the mapping of the keys fully configurable. 51 52The meaning of every key is programmable via the PIO_KEYMAP ioctl call, that 53takes a structure keymap_t as argument. The layout of this structure is as 54follows: 55.Pp 56.Bd -literal -offset indent 57 struct keymap { 58 u_short n_keys; 59 struct key_t { 60 u_char map[NUM_STATES]; 61 u_char spcl; 62 u_char flgs; 63 } key[NUM_KEYS]; 64 }; 65.Ed 66.Pp 67The field n_keys tells the system how many keydefinitions (scancodes) 68follows. Each scancode is then specified in the key_t substructure. 69 70Each scancode can be translated to any of 8 different values, depending 71on the shift, control, and alt state. These eight possibilities is 72represented by the map array, as shown below: 73 74 alt 75 scan cntrl alt alt cntrl 76 code base shift cntrl shift alt shift cntrl shift 77 map[n] 0 1 2 3 4 5 6 7 78 ---- ------------------------------------------------------ 79 0x1E 'a' 'A' 0x01 0x01 'a' 'A' 0x01 0x01 80 81This is the default mapping for the key labelled 'A' wich normally has 82scancode 0x1E. The eight states is as shown, giving the 'A' key its 83normal behavior. 84The spcl field is used to give the key "special" treatment, and is 85interpreted as follows. 86Each bit correspond to one of the states above. If the bit is 0 the 87key emits the number defined in the corresponding map[] entry. 88If the bit is 1 the key is "special". This means it does not emit 89anything, instead it changes the "state". That means it is a shift, 90control, alt, lock, switch-screen, function-key or no-op key. 91The bitmap is backwards ie. 7 for base, 6 for shift etc. 92 93The flgs field defines if the key should react on caps-lock (1), 94num-lock (2), both (3) or ignore both (0). 95 96The kbdcontrol utility is used to load such a description into/outof 97the kernel at runtime. This make it possible to change the key 98assignments at runtime, or more important to get (GIO_KEYMAP ioctl) 99the exact key meanings from the kernel (fx. used by the X server). 100 101The function keys can be programmed using the SETFKEY ioctl call. 102 103This ioctl takes a argument of the type fkeyarg_t: 104.Bd -literal -offset indent 105 struct fkeyarg { 106 u_short keynum; 107 char keydef[MAXFK]; 108 char flen; 109 }; 110.Ed 111.Pp 112The field keynum defines which function key that is programmed. 113The array keydef should contain the new string to be used (MAXFK long), 114and the length should be entered in flen. 115 116The GETFKEY ioctl call works in a semilar manner, execpt it returns 117the current setting of keynum. 118 119The function keys are numbered like this: 120.Bd -literal -offset indent 121 F1-F12 key 1 - 12 122 Shift F1-F12 key 13 - 24 123 Ctrl F1-F12 key 25 - 36 124 Ctrl+shift F1-F12 key 37 - 48 125 126 Home key 49 127 Up arrow key 50 128 Page Up key 51 129 (keypad) - key 52 130 Left arrow key 53 131 (keypad) 5 key 54 132 Right arrow key 55 133 (keypad) + key 56 134 End key 57 135 Down arrow key 58 136 Page down key 59 137 Insert key 60 138 Delete key 61 139 140 Right window key 62 141 Left window key 63 142 Menu key 64 143.Ed 144 145The kbdcontrol utility also allows changing these values at runtime. 146.Pp 147.Sh AUTHOR 148 S�ren Schmidt (sos@FreeBSD.org) 149