xref: /dragonfly/share/man/man4/keyboard.4 (revision 6b5c5d0d) 
1.\"
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
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.Pp
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.Pp
38The keyboard is configurable to suit the individual user and the different
39national layout.
40.Pp
41The keys on the keyboard can have any of the following functions:
42.Pp
43.Bl -tag -width "Modifier Key" -compact
44.It "Normal key"
45Enter the ASCII value associated with the key.
46.It "Function key"
47Enter a string of ASCII values.
48.It "Switch Key"
49Switch virtual console.
50.It "Modifier Key"
51Change the meaning of another key.
52.El
53.Pp
54The keyboard is seen as a number of keys numbered from 1 to n. This
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
63.Dv PIO_KEYMAP
64ioctl call, that
65takes a structure keymap_t as argument.
66The layout of this structure is as
67follows:
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
80The field n_keys tells the system how many keydefinitions (scancodes)
81follows.
82Each scancode is then specified in the key_t substructure.
83.Pp
84Each scancode can be translated to any of 8 different values, depending
85on the shift, control, and alt state.
86These eight possibilities are
87represented 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
97This is the default mapping for the key labelled 'A' which normally has
98scancode 0x1E. The eight states are as shown, giving the 'A' key its
99normal behavior.
100The spcl field is used to give the key "special" treatment, and is
101interpreted as follows.
102Each bit corresponds to one of the states above.
103If the bit is 0 the
104key emits the number defined in the corresponding map[] entry.
105If the bit is 1 the key is "special". This means it does not emit
106anything; instead it changes the "state". That means it is a shift,
107control, alt, lock, switch-screen, function-key or no-op key.
108The bitmap is backwards ie. 7 for base, 6 for shift etc.
109.Pp
110The flgs field defines if the key should react on caps-lock (1),
111num-lock (2), both (3) or ignore both (0).
112.Pp
113The
114.Xr kbdcontrol 1
115utility is used to load such a description into/outof
116the kernel at runtime.
117This makes it possible to change the key
118assignments at runtime, or more important to get
119.Dv ( GIO_KEYMAP
120ioctl)
121the exact key meanings from the kernel (fx. used by the X server).
122.Pp
123The function keys can be programmed using the
124.Dv SETFKEY
125ioctl call.
126.Pp
127This 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
136The field keynum defines which function key that is programmed.
137The array keydef should contain the new string to be used (MAXFK long),
138and the length should be entered in flen.
139.Pp
140The
141.Dv GETFKEY
142ioctl call works in a similar manner, except it returns
143the current setting of keynum.
144.Pp
145The 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
151
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
165
166	Right window		key 62
167	Left window		key 63
168	Menu			key 64
169.Ed
170.Pp
171The
172.Xr kbdcontrol 1
173utility also allows changing these values at runtime.
174.Sh AUTHORS
175.An S\(/oren Schmidt Aq sos@FreeBSD.org
176