1.\" 2.\" $FreeBSD$ 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. 54This 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. 97The 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". 105This means it does not emit 106anything; instead it changes the "state". 107That means it is a shift, 108control, alt, lock, switch-screen, function-key or no-op key. 109The bitmap is backwards i.e., 1107 for base, 6 for shift etc. 111.Pp 112The flgs field defines if the key should react on caps-lock (1), 113num-lock (2), both (3) or ignore both (0). 114.Pp 115The 116.Xr kbdcontrol 1 117utility is used to load such a description into/outof 118the kernel at runtime. 119This makes it possible to change the key 120assignments at runtime, or more important to get (GIO_KEYMAP ioctl) 121the exact key meanings from the kernel (e.g.\& used by the X server). 122.Pp 123The function keys can be programmed using the SETFKEY ioctl 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 GETFKEY ioctl call works in a similar manner, except it returns 139the current setting of keynum. 140.Pp 141The function keys are numbered like this: 142.Bd -literal -offset indent 143 F1-F12 key 1 - 12 144 Shift F1-F12 key 13 - 24 145 Ctrl F1-F12 key 25 - 36 146 Ctrl+shift F1-F12 key 37 - 48 147 148 Home key 49 149 Up arrow key 50 150 Page Up key 51 151 (keypad) - key 52 152 Left arrow key 53 153 (keypad) 5 key 54 154 Right arrow key 55 155 (keypad) + key 56 156 End key 57 157 Down arrow key 58 158 Page down key 59 159 Insert key 60 160 Delete key 61 161 162 Left window key 62 163 Right window key 63 164 Menu key 64 165.Ed 166.Pp 167The 168.Xr kbdcontrol 1 169utility also allows changing these values at runtime. 170.Sh AUTHORS 171.An S\(/oren Schmidt Aq sos@FreeBSD.org 172