screen.4 revision 735 
1.Dd April 7, 1993
2.Dt SCREEN 4
3.Os FreeBSD
4.Sh NAME
5.Nm screen
6.Nd pc display interface
7.Sh DESCRIPTION
8
9Access to the
10.Ar virtual consoles 
11are obtained through the device files
12ttyv0 - ttyvb in /dev.
13Each of these files correspond to a seperate
14virtual console.
15All virtual console devices can be open at once, but only one is 
16active at a time. The active virtual console "owns" the keyboard and
17display screen.
18.Pp
19Output to a virtual console that not currently is on the display is
20saved in a buffer that holds a "screenfull" (normally 25) lines.
21Any output written to 
22.Ar /dev/console 
23(the original console device) is echoed to /dev/ttyv0.
24.Pp
25To switch between the virtual consoles one uses the sequence 
26.Ar ALT+Fn
27, which means hold down ALT and press one of the function keys. The 
28virtual console with the same number as the function key is then
29selected as the current virtual console, and given exclusive use of
30the keyboard and display. This switch sequence can be changed via
31the keyboard mapping ioctl call (see keyboard.man)
32.Pp
33The number of virtual consoles is changeable in the system config 
34file, and need recompilation of the kernel to take any effect. The
35default is 12.
36
37The console allows entering values that are not physically
38present on the keyboard via a special keysequence.
39To use this facility press and hold down ALT,
40then enter a decimal number from 0-255 via the numerical keypad, then
41release ALT. The entered value is then used as the ASCII value for one
42character. This way it is possible to enter any ASCII value.
43
44The console understands a subset of the ANSI x3.64 character 
45sequences. For compatibility with the old pccons, the PC3 character
46sequences is also supported.
47.Pp
48.Bd -literal 
49ANSI	Seq	Function				Termcap entry
50======= ======= =====================================   ==============
51
52CUU	E[nA	move cursor up n lines			up (ku)
53
54CUD	E[nB	move cursor down n lines		do (kd)
55
56CUF	E[nC	move cursor right n characters		nd (kr)
57
58CUB	E[nD	move cursor left n characters		bs (kl)
59
60HPA	E[n`	move cursor character position n	--
61
62HPR	E[na	move cursor right n characters 		--
63
64VPA	E[nd	move cursor to line n			--
65
66VPR	E[ne	move cursor down n lines		--
67
68CPL	E[nF	move cursor to start of line,		--
69		n lines up
70
71CNL	E[nF	move cursor to start of line,		--
72		n lines down
73
74CUP	E[y;xH	Move cursor to x, y			cm
75
76HVP	E[y;xf	Move cursor to x, y			--
77
78CBT	E[nZ	Move cursor back n tab stops		bt
79
80IL	E[nL	Insert n blank lines			al
81
82ICH	E[n@	Insert n blank characters		ic
83
84DL	E[nM	Delete n lines				dl
85
86DCH	E[nP	Delete n characters			dc
87
88ED	E[nJ	Erase part or all of display:		cd
89		n=0 from cursor to end of display,
90		n=1 from begin of display to cursor,
91		n=2 entire display.
92
93EL	E[nK	Erase part or all of line:		ce
94		n=0 from cursor to end of line,
95		n=1 from begin of line to cursor,
96		n=2 entire line.
97
98ECH	E[nX	Erase n characters			--
99
100SU	E[nS	Scroll display n lines up (forward)	sf
101
102SD	E[nT	Scroll display n lines down (reverse)	sr
103
104
105SGR	E[nm	Set character attributes:		--
106		n= 0 normal attribute (all off)
107		n= 1 bold (highlight)
108		n= 4 underscore (if supported by HW)
109		n= 5 blink (if supported by HW)
110		n= 7 reverse 
111		n=3X set foreground color (see table)
112		n=4X set background color (see table)
113
114		   X=0 black 	X=1 red
115		   X=2 green	X=3 brown
116		   X=4 blue	X=5 magenta
117		   X=6 cyan 	X=7 white
118
119
120--	E[=p;dB	Set bell pitch (p) and duration (d),	--
121			picth is in units of 840 nS, 
122			duration is units of 0,1 S.
123
124--	E[=s:eC	Set cursor start and end scanline,	--
125			start on line s, end on line e.
126
127--	E[=nA	Set the border color to color n
128		(see table) (if supported by HW)
129
130--	E[=cF	set normal foreground color to n 	--
131		(see table)
132
133--	E[=cG	set normal background color to n 	--
134		(see table)
135
136--	E[=cH	set reverse foreground color to n 	--
137		(see table)
138
139--	E[=cI	set reverse background color to n 	--
140		(see table)
141
142		   n= 0 black	n= 8 grey
143		   n= 1 blue	n= 9 light blue
144		   n= 2 green	n=10 light green
145		   n= 3 cyan	n=11 light cyan
146		   n= 4 red	n=12 light red
147		   n= 5 magenta n=13 light magenta
148		   n= 6 brown	n=14 yellow
149		   n= 7 white	n=15 light white
150
151note: the first E in the sequences stands for ESC (0x1b)
152
153.Ed
154.Pp
155.Sh AUTHOR
156 S_ren Schmidt 
157 Email: (baukno@login.dkuug.dk -or- sos@kmd-ac.dk)
158