1.\" 2.\" $FreeBSD$ 3.\" 4.Dd January 8, 1995 5.Dt KEYBOARD 4 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. 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 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 38The keyboard is configurable to suit the individual user and the different 39national layout. 40 41The keys on the keyboard can have any of the following functions: 42 43 Normal key - Enter the ASCII value associated with the key. 44 45 Function key - Enter a string of ASCII values. 46 47 Switch Key - Switch virtual console. 48 49 Modifier Key - Change the meaning of another key. 50 51 52The keyboard is seen as a number of keys numbered from 1 to n. This 53number is often referred to as the "scancode" for a given key. 54The number 55of the key is transmitted as an 8 bit char with bit 7 as 0 when a key is 56pressed, and the number with bit 7 as 1 when released. 57This makes it 58possible to make the mapping of the keys fully configurable. 59 60The meaning of every key is programmable via the PIO_KEYMAP ioctl call, that 61takes a structure keymap_t as argument. 62The layout of this structure is as 63follows: 64.Pp 65.Bd -literal -offset indent 66 struct keymap { 67 u_short n_keys; 68 struct key_t { 69 u_char map[NUM_STATES]; 70 u_char spcl; 71 u_char flgs; 72 } key[NUM_KEYS]; 73 }; 74.Ed 75.Pp 76The field n_keys tells the system how many keydefinitions (scancodes) 77follows. 78Each scancode is then specified in the key_t substructure. 79 80Each scancode can be translated to any of 8 different values, depending 81on the shift, control, and alt state. 82These eight possibilities are 83represented by the map array, as shown below: 84 85 alt 86 scan cntrl alt alt cntrl 87 code base shift cntrl shift alt shift cntrl shift 88 map[n] 0 1 2 3 4 5 6 7 89 ---- ------------------------------------------------------ 90 0x1E 'a' 'A' 0x01 0x01 'a' 'A' 0x01 0x01 91 92This is the default mapping for the key labelled 'A' which normally has 93scancode 0x1E. The eight states are as shown, giving the 'A' key its 94normal behavior. 95The spcl field is used to give the key "special" treatment, and is 96interpreted as follows. 97Each bit corresponds to one of the states above. 98If the bit is 0 the 99key emits the number defined in the corresponding map[] entry. 100If the bit is 1 the key is "special". This means it does not emit 101anything; instead it changes the "state". That means it is a shift, 102control, alt, lock, switch-screen, function-key or no-op key. 103The bitmap is backwards ie. 7 for base, 6 for shift etc. 104 105The flgs field defines if the key should react on caps-lock (1), 106num-lock (2), both (3) or ignore both (0). 107 108The 109.Xr kbdcontrol 1 110utility is used to load such a description into/outof 111the kernel at runtime. 112This makes it possible to change the key 113assignments at runtime, or more important to get (GIO_KEYMAP ioctl) 114the exact key meanings from the kernel (fx. used by the X server). 115 116The function keys can be programmed using the SETFKEY ioctl call. 117 118This ioctl takes a argument of the type fkeyarg_t: 119.Bd -literal -offset indent 120 struct fkeyarg { 121 u_short keynum; 122 char keydef[MAXFK]; 123 char flen; 124 }; 125.Ed 126.Pp 127The field keynum defines which function key that is programmed. 128The array keydef should contain the new string to be used (MAXFK long), 129and the length should be entered in flen. 130 131The GETFKEY ioctl call works in a similar manner, except it returns 132the current setting of keynum. 133 134The function keys are numbered like this: 135.Bd -literal -offset indent 136 F1-F12 key 1 - 12 137 Shift F1-F12 key 13 - 24 138 Ctrl F1-F12 key 25 - 36 139 Ctrl+shift F1-F12 key 37 - 48 140 141 Home key 49 142 Up arrow key 50 143 Page Up key 51 144 (keypad) - key 52 145 Left arrow key 53 146 (keypad) 5 key 54 147 Right arrow key 55 148 (keypad) + key 56 149 End key 57 150 Down arrow key 58 151 Page down key 59 152 Insert key 60 153 Delete key 61 154 155 Right window key 62 156 Left window key 63 157 Menu key 64 158.Ed 159 160The 161.Xr kbdcontrol 1 162utility also allows changing these values at runtime. 163.Pp 164.Sh AUTHORS 165.An S\(/oren Schmidt Aq sos@FreeBSD.org 166