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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 1.3 2007/11/04 19:04:42 swildner 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
12 The PC keyboard is used as the console character input device.
13 The keyboard
14 is owned by the current virtual console.
15 To switch between the virtual consoles use the sequence
16 .Ar ALT+Fn ,
17 which means hold down ALT and press one of the function keys.
18 The
19 virtual console with the same number as the function key is then
20 selected as the current virtual console and given exclusive use of
21 the keyboard and display.
22 .Pp
23 The console allows entering values that are not physically
24 present on the keyboard via a special keysequence.
25 To use this facility press and hold down ALT,
26 then enter a decimal number from 0-255 via the numerical keypad, then
27 release ALT.
28 The entered value is then used as the ASCII value for one
29 character.
30 This way it is possible to enter any ASCII value, not present
31 on the keyboard.
32 The console driver also includes a history function.
33 It is activated by
34 pressing the scroll-lock key.
35 This holds the display, and enables the cursor
36 arrows for scrolling up and down through the last scrolled out lines.
37 .Pp
38 The keyboard is configurable to suit the individual user and the different
39 national layout.
40 .Pp
41 The keys on the keyboard can have any of the following functions:
42 .Pp
43 .Bl -tag -width "Modifier Key" -compact
44 .It "Normal key"
45 Enter the ASCII value associated with the key.
46 .It "Function key"
47 Enter a string of ASCII values.
48 .It "Switch Key"
49 Switch virtual console.
50 .It "Modifier Key"
51 Change the meaning of another key.
52 .El
53 .Pp
54 The keyboard is seen as a number of keys numbered from 1 to n. This
55 number is often referred to as the "scancode" for a given key.
56 The number
57 of the key is transmitted as an 8 bit char with bit 7 as 0 when a key is
58 pressed, and the number with bit 7 as 1 when released.
59 This makes it
60 possible to make the mapping of the keys fully configurable.
61 .Pp
62 The meaning of every key is programmable via the
63 .Dv PIO_KEYMAP
64 ioctl call, that
65 takes a structure keymap_t as argument.
66 The layout of this structure is as
67 follows:
68 .Pp
69 .Bd -literal -offset indent
70 struct keymap {
71 u_short n_keys;
72 struct key_t {
73 u_char map[NUM_STATES];
74 u_char spcl;
75 u_char flgs;
76 } key[NUM_KEYS];
77 };
78 .Ed
79 .Pp
80 The field n_keys tells the system how many keydefinitions (scancodes)
81 follows.
82 Each scancode is then specified in the key_t substructure.
83 .Pp
84 Each scancode can be translated to any of 8 different values, depending
85 on the shift, control, and alt state.
86 These eight possibilities are
87 represented by the map array, as shown below:
88 .Bd -literal
89 alt
90 scan cntrl alt alt cntrl
91 code base shift cntrl shift alt shift cntrl shift
92 map[n] 0 1 2 3 4 5 6 7
93 ---- ------------------------------------------------------
94 0x1E 'a' 'A' 0x01 0x01 'a' 'A' 0x01 0x01
95 .Ed
96 .Pp
97 This is the default mapping for the key labelled 'A' which normally has
98 scancode 0x1E. The eight states are as shown, giving the 'A' key its
99 normal behavior.
100 The spcl field is used to give the key "special" treatment, and is
101 interpreted as follows.
102 Each bit corresponds to one of the states above.
103 If the bit is 0 the
104 key emits the number defined in the corresponding map[] entry.
105 If the bit is 1 the key is "special". This means it does not emit
106 anything; instead it changes the "state". That means it is a shift,
107 control, alt, lock, switch-screen, function-key or no-op key.
108 The bitmap is backwards ie. 7 for base, 6 for shift etc.
109 .Pp
110 The flgs field defines if the key should react on caps-lock (1),
111 num-lock (2), both (3) or ignore both (0).
112 .Pp
113 The
114 .Xr kbdcontrol 1
115 utility is used to load such a description into/outof
116 the kernel at runtime.
117 This makes it possible to change the key
118 assignments at runtime, or more important to get
119 .Dv ( GIO_KEYMAP
120 ioctl)
121 the exact key meanings from the kernel (fx. used by the X server).
122 .Pp
123 The function keys can be programmed using the
124 .Dv SETFKEY
125 ioctl call.
126 .Pp
127 This ioctl takes a argument of the type fkeyarg_t:
128 .Bd -literal -offset indent
129 struct fkeyarg {
130 u_short keynum;
131 char keydef[MAXFK];
132 char flen;
133 };
134 .Ed
135 .Pp
136 The field keynum defines which function key that is programmed.
137 The array keydef should contain the new string to be used (MAXFK long),
138 and the length should be entered in flen.
139 .Pp
140 The
141 .Dv GETFKEY
142 ioctl call works in a similar manner, except it returns
143 the current setting of keynum.
144 .Pp
145 The function keys are numbered like this:
146 .Bd -literal -offset indent
147 F1-F12 key 1 - 12
148 Shift F1-F12 key 13 - 24
149 Ctrl F1-F12 key 25 - 36
150 Ctrl+shift F1-F12 key 37 - 48
152 Home key 49
153 Up arrow key 50
154 Page Up key 51
155 (keypad) - key 52
156 Left arrow key 53
157 (keypad) 5 key 54
158 Right arrow key 55
159 (keypad) + key 56
160 End key 57
161 Down arrow key 58
162 Page down key 59
163 Insert key 60
164 Delete key 61
166 Right window key 62
167 Left window key 63
168 Menu key 64
169 .Ed
170 .Pp
171 The
172 .Xr kbdcontrol 1
173 utility also allows changing these values at runtime.
174 .Sh AUTHORS
175 .An S\(/oren Schmidt Aq sos@FreeBSD.org