2 .\" $Id: keyboard.4,v 1.15 1998/06/29 06:56:40 hoek Exp $
9 .Nd pc keyboard interface
12 The PC keyboard is used as the console character input device. The keyboard
13 is owned by the current virtual console.
14 To switch between the virtual consoles use the sequence
16 which means hold down ALT and press one of the function keys. The
17 virtual console with the same number as the function key is then
18 selected as the current virtual console and given exclusive use of
19 the keyboard and display.
21 The console allows entering values that are not physically
22 present on the keyboard via a special keysequence.
23 To use this facility press and hold down ALT,
24 then enter a decimal number from 0-255 via the numerical keypad, then
25 release ALT. The entered value is then used as the ASCII value for one
26 character. This way it is possible to enter any ASCII value, not present
28 The console driver also includes a history function. It is activated by
29 pressing the scroll-lock key. This holds the display, and enables the cursor
30 arrows for scrolling up and down through the last scrolled out lines.
32 The keyboard is configurable to suit the individual user and the different
35 The keys on the keyboard can have any of the following functions:
37 Normal key - Enter the ASCII value associated with the key.
39 Function key - Enter a string of ASCII values.
41 Switch Key - Switch virtual console.
43 Modifier Key - Change the meaning of another key.
46 The keyboard is seen as a number of keys numbered from 1 to n. This
47 number is often referred to as the "scancode" for a given key. The number
48 of the key is transmitted as an 8 bit char with bit 7 as 0 when a key is
49 pressed, and the number with bit 7 as 1 when released. This makes it
50 possible to make the mapping of the keys fully configurable.
52 The meaning of every key is programmable via the PIO_KEYMAP ioctl call, that
53 takes a structure keymap_t as argument. The layout of this structure is as
56 .Bd -literal -offset indent
60 u_char map[NUM_STATES];
67 The field n_keys tells the system how many keydefinitions (scancodes)
68 follows. Each scancode is then specified in the key_t substructure.
70 Each scancode can be translated to any of 8 different values, depending
71 on the shift, control, and alt state. These eight possibilities are
72 represented by the map array, as shown below:
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
81 This is the default mapping for the key labelled 'A' which normally has
82 scancode 0x1E. The eight states are as shown, giving the 'A' key its
84 The spcl field is used to give the key "special" treatment, and is
85 interpreted as follows.
86 Each bit corresponds to one of the states above. If the bit is 0 the
87 key emits the number defined in the corresponding map[] entry.
88 If the bit is 1 the key is "special". This means it does not emit
89 anything; instead it changes the "state". That means it is a shift,
90 control, alt, lock, switch-screen, function-key or no-op key.
91 The bitmap is backwards ie. 7 for base, 6 for shift etc.
93 The flgs field defines if the key should react on caps-lock (1),
94 num-lock (2), both (3) or ignore both (0).
98 utility is used to load such a description into/outof
99 the kernel at runtime. This makes it possible to change the key
100 assignments at runtime, or more important to get (GIO_KEYMAP ioctl)
101 the exact key meanings from the kernel (fx. used by the X server).
103 The function keys can be programmed using the SETFKEY ioctl call.
105 This ioctl takes a argument of the type fkeyarg_t:
106 .Bd -literal -offset indent
114 The field keynum defines which function key that is programmed.
115 The array keydef should contain the new string to be used (MAXFK long),
116 and the length should be entered in flen.
118 The GETFKEY ioctl call works in a similar manner, except it returns
119 the current setting of keynum.
121 The function keys are numbered like this:
122 .Bd -literal -offset indent
124 Shift F1-F12 key 13 - 24
125 Ctrl F1-F12 key 25 - 36
126 Ctrl+shift F1-F12 key 37 - 48
149 utility also allows changing these values at runtime.
152 .An Søren Schmidt Aq sos@FreeBSD.org