<s>
In	O
computing	O
,	O
text-based	B-Application
user	I-Application
interfaces	I-Application
(	O
TUI	O
)	O
(	O
alternately	O
terminal	B-Application
user	I-Application
interfaces	I-Application
,	O
to	O
reflect	O
a	O
dependence	O
upon	O
the	O
properties	O
of	O
computer	B-General_Concept
terminals	I-General_Concept
and	O
not	O
just	O
text	O
)	O
,	O
is	O
a	O
retronym	O
describing	O
a	O
type	O
of	O
user	B-Application
interface	I-Application
(	O
UI	B-Application
)	O
common	O
as	O
an	O
early	O
form	O
of	O
human	O
–	O
computer	O
interaction	O
,	O
before	O
the	O
advent	O
of	O
modern	O
conventional	O
graphical	B-Application
user	I-Application
interfaces	I-Application
(	O
GUIs	B-Application
)	O
.	O
</s>
<s>
Like	O
GUIs	B-Application
,	O
they	O
may	O
use	O
the	O
entire	O
screen	B-Device
area	O
and	O
accept	O
mouse	B-Device
and	O
other	O
inputs	O
.	O
</s>
<s>
The	O
modern	O
context	O
of	O
use	O
is	O
usually	O
a	O
terminal	B-Application
emulator	I-Application
.	O
</s>
<s>
From	O
text	B-Device
application	I-Device
's	O
point	O
of	O
view	O
,	O
a	O
text	O
screen	B-Device
(	O
and	O
communications	O
with	O
it	O
)	O
can	O
belong	O
to	O
one	O
of	O
three	O
types	O
(	O
here	O
ordered	O
in	O
order	O
of	O
decreasing	O
accessibility	O
)	O
:	O
</s>
<s>
A	O
genuine	O
text	B-Application
mode	I-Application
display	O
,	O
controlled	O
by	O
a	O
video	B-Device
adapter	I-Device
or	O
the	O
central	O
processor	O
itself	O
.	O
</s>
<s>
This	O
is	O
a	O
normal	O
condition	O
for	O
a	O
locally	O
running	O
application	O
on	O
various	O
types	O
of	O
personal	B-Device
computers	I-Device
and	O
mobile	B-Application
devices	I-Application
.	O
</s>
<s>
If	O
not	O
deterred	O
by	O
the	O
operating	B-General_Concept
system	I-General_Concept
,	O
a	O
smart	O
program	O
may	O
exploit	O
the	O
full	O
power	O
of	O
a	O
hardware	B-Application
text	I-Application
mode	I-Application
.	O
</s>
<s>
A	O
text	B-Application
mode	I-Application
emulator	B-Application
.	O
</s>
<s>
Examples	O
are	O
xterm	B-Language
for	O
X	O
Window	O
System	O
and	O
win32	B-Application
console	I-Application
(	O
in	O
a	O
window	O
mode	O
)	O
for	O
Microsoft	B-Application
Windows	I-Application
.	O
</s>
<s>
This	O
usually	O
supports	O
programs	O
which	O
expect	O
a	O
real	O
text	B-Application
mode	I-Application
display	O
,	O
but	O
may	O
run	O
considerably	O
slower	O
.	O
</s>
<s>
Certain	O
functions	O
of	O
an	O
advanced	O
text	B-Application
mode	I-Application
,	O
such	O
as	O
an	O
own	O
font	O
uploading	O
,	O
almost	O
certainly	O
become	O
unavailable	O
.	O
</s>
<s>
The	O
communication	O
capabilities	O
usually	O
become	O
reduced	O
to	O
a	O
serial	B-Protocol
line	I-Protocol
or	O
its	O
emulation	B-Application
,	O
possibly	O
with	O
few	O
ioctl( )	O
s	O
as	O
an	O
out-of-band	B-Protocol
channel	O
in	O
such	O
cases	O
as	O
Telnet	B-Protocol
and	O
Secure	B-Protocol
Shell	I-Protocol
.	O
</s>
<s>
Under	O
Linux	B-Application
and	O
other	O
Unix-like	B-Operating_System
systems	I-Operating_System
,	O
a	O
program	O
easily	O
accommodates	B-General_Concept
to	O
any	O
of	O
the	O
three	O
cases	O
because	O
the	O
same	O
interface	O
(	O
namely	O
,	O
standard	B-Operating_System
streams	I-Operating_System
)	O
controls	O
the	O
display	O
and	O
keyboard	O
.	O
</s>
<s>
Many	O
TUI	O
programming	B-Library
libraries	I-Library
are	O
available	O
to	O
help	O
developers	O
build	O
TUI	B-Device
applications	I-Device
.	O
</s>
<s>
On	O
IBM	B-Device
Personal	I-Device
Computers	I-Device
and	O
compatibles	O
,	O
the	O
Basic	B-Operating_System
Input	I-Operating_System
Output	I-Operating_System
System	I-Operating_System
(	O
BIOS	B-Operating_System
)	O
and	O
DOS	B-Device
system	O
calls	O
provide	O
a	O
way	O
to	O
write	O
text	O
on	O
the	O
screen	B-Device
,	O
and	O
the	O
ANSI.SYS	O
driver	O
could	O
process	O
standard	O
ANSI	O
escape	O
sequences	O
.	O
</s>
<s>
However	O
,	O
programmers	O
soon	O
learned	O
that	O
writing	O
data	O
directly	O
to	O
the	O
screen	B-Algorithm
buffer	I-Algorithm
was	O
far	O
faster	O
and	O
simpler	O
to	O
program	O
,	O
and	O
less	O
error-prone	O
;	O
see	O
VGA-compatible	B-Device
text	I-Device
mode	I-Device
for	O
details	O
.	O
</s>
<s>
This	O
change	O
in	O
programming	O
methods	O
resulted	O
in	O
many	O
DOS	B-Device
TUI	O
programs	O
.	O
</s>
<s>
The	O
Windows	B-Application
console	I-Application
environment	O
is	O
notorious	O
for	O
its	O
emulation	B-Application
of	O
certain	O
EGA/VGA	O
text	O
mode	O
features	O
,	O
particularly	O
random	O
access	O
to	O
the	O
text	O
buffer	O
,	O
even	O
if	O
the	O
application	O
runs	O
in	O
a	O
window	O
.	O
</s>
<s>
On	O
the	O
other	O
hand	O
,	O
programs	O
running	O
under	O
Windows	O
(	O
both	O
native	O
and	O
DOS	B-Device
applications	O
)	O
have	O
much	O
less	O
control	O
of	O
the	O
display	O
and	O
keyboard	O
than	O
Linux	B-Application
and	O
DOS	B-Device
programs	O
can	O
have	O
,	O
because	O
of	O
aforementioned	O
Windows	B-Application
console	I-Application
layer	O
.	O
</s>
<s>
Most	O
often	O
those	O
programs	O
used	O
a	O
blue	O
background	O
for	O
the	O
main	O
screen	B-Device
,	O
with	O
white	O
or	O
yellow	O
characters	O
,	O
although	O
commonly	O
they	O
had	O
also	O
user	O
color	O
customization	O
.	O
</s>
<s>
Later	O
,	O
the	O
interface	O
became	O
deeply	O
influenced	O
by	O
graphical	B-Application
user	I-Application
interfaces	I-Application
(	O
GUI	B-Application
)	O
,	O
adding	O
pull-down	O
menus	O
,	O
overlapping	O
windows	O
,	O
dialog	B-Device
boxes	O
and	O
GUI	B-Application
widgets	O
operated	O
by	O
mnemonics	B-Device
or	O
keyboard	O
shortcuts	O
.	O
</s>
<s>
Soon	O
mouse	B-Device
input	I-Device
was	O
added	O
–	O
either	O
at	O
text	O
resolution	O
as	O
a	O
simple	O
colored	O
box	O
or	O
at	O
graphical	O
resolution	O
thanks	O
to	O
the	O
ability	O
of	O
the	O
Enhanced	B-Device
Graphics	I-Device
Adapter	I-Device
(	O
EGA	B-Device
)	O
and	O
Video	B-Protocol
Graphics	I-Protocol
Array	I-Protocol
(	O
VGA	B-Protocol
)	O
display	B-Device
adapters	I-Device
to	O
redefine	O
the	O
text	O
character	O
shapes	O
by	O
software	O
–	O
providing	O
additional	O
functions	O
.	O
</s>
<s>
Some	O
notable	O
programs	O
of	O
this	O
kind	O
were	O
Microsoft	B-Application
Word	I-Application
,	O
DOS	B-Application
Shell	I-Application
,	O
WordPerfect	B-Application
,	O
Norton	B-Application
Commander	I-Application
,	O
Turbo	B-Application
Vision	I-Application
based	O
Borland	O
Turbo	B-Application
Pascal	I-Application
and	O
Turbo	B-Application
C	I-Application
(	O
the	O
latter	O
included	O
the	O
conio	B-Language
library	B-Library
)	O
,	O
Lotus	B-Application
1-2-3	I-Application
and	O
many	O
others	O
.	O
</s>
<s>
Some	O
of	O
these	O
interfaces	B-Application
survived	O
even	O
during	O
the	O
Microsoft	B-Application
Windows	I-Application
3.1x	I-Application
period	O
in	O
the	O
early	O
1990s	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
Microsoft	O
C	O
6.0	O
compiler	O
,	O
used	O
to	O
write	O
true	O
GUI	B-Application
programs	O
under	O
16-bit	B-Device
Windows	O
,	O
still	O
has	O
its	O
own	O
TUI	O
.	O
</s>
<s>
Since	O
its	O
start	O
,	O
Microsoft	B-Application
Windows	I-Application
includes	O
a	O
console	O
to	O
display	O
DOS	B-Device
software	O
.	O
</s>
<s>
Later	O
versions	O
added	O
the	O
Windows	B-Application
console	I-Application
as	O
a	O
native	O
interface	O
for	O
command-line	B-Application
interface	I-Application
and	O
TUI	O
programs	O
.	O
</s>
<s>
The	O
console	O
usually	O
opens	O
in	O
window	O
mode	O
,	O
but	O
it	O
can	O
be	O
switched	O
to	O
full	O
,	O
true	O
text	B-Application
mode	I-Application
screen	B-Device
and	O
vice	O
versa	O
by	O
pressing	O
the	O
Alt	B-Device
and	O
Enter	B-Device
keys	I-Device
together	O
.	O
</s>
<s>
Full-screen	O
mode	O
is	O
not	O
available	O
in	O
Windows	O
Vista	O
and	O
later	O
,	O
but	O
may	O
be	O
used	O
with	O
some	O
workarounds	O
.	O
</s>
<s>
Windows	B-Language
Terminal	I-Language
is	O
a	O
multi-tabbed	O
terminal	B-Application
emulator	I-Application
that	O
Microsoft	O
has	O
developed	O
for	O
Windows	B-Operating_System
10	I-Operating_System
and	O
later	O
as	O
a	O
replacement	O
for	O
Windows	B-Application
Console	I-Application
.	O
</s>
<s>
The	O
Windows	O
Subsystem	O
for	O
Linux	B-Application
which	O
was	O
added	O
to	O
Windows	O
by	O
Microsoft	O
in	O
2019	O
,	O
supports	O
running	O
Linux	B-Application
text-based	B-Application
apps	O
on	O
Windows	O
,	O
within	O
Windows	B-Application
console	I-Application
,	O
Windows	B-Language
Terminal	I-Language
,	O
and	O
other	O
Windows-based	O
terminals	O
.	O
</s>
<s>
the	O
alternative	O
S-Lang	B-Device
library	B-Library
.	O
</s>
<s>
The	O
advent	O
of	O
the	O
curses	B-Device
library	B-Library
with	O
Berkeley	B-Operating_System
Unix	I-Operating_System
created	O
a	O
portable	O
and	O
stable	O
API	B-Application
for	O
which	O
to	O
write	O
TUIs	O
.	O
</s>
<s>
The	O
ability	O
to	O
talk	O
to	O
various	O
text	O
terminal	O
types	O
using	O
the	O
same	O
interfaces	B-Application
led	O
to	O
more	O
widespread	O
use	O
of	O
"	O
visual	O
"	O
Unix	O
programs	O
,	O
which	O
occupied	O
the	O
entire	O
terminal	O
screen	B-Device
instead	O
of	O
using	O
a	O
simple	O
line	O
interface	O
.	O
</s>
<s>
This	O
can	O
be	O
seen	O
in	O
text	B-Application
editors	I-Application
such	O
as	O
vi	B-Application
,	O
mail	B-Protocol
clients	I-Protocol
such	O
as	O
pine	B-Operating_System
or	O
mutt	B-Device
,	O
system	O
management	O
tools	O
such	O
as	O
SMIT	B-Device
,	O
SAM	O
,	O
FreeBSD	B-Operating_System
's	O
Sysinstall	O
and	O
web	B-Application
browsers	I-Application
such	O
as	O
lynx	B-Application
.	O
</s>
<s>
Some	O
applications	O
,	O
such	O
as	O
w3m	B-Application
,	O
and	O
older	O
versions	O
of	O
pine	B-Operating_System
and	O
vi	B-Application
use	O
the	O
less-able	O
termcap	B-Application
library	B-Library
,	O
performing	O
many	O
of	O
the	O
functions	O
associated	O
with	O
curses	B-Device
within	O
the	O
application	O
.	O
</s>
<s>
Custom	O
TUI	B-Device
applications	I-Device
based	O
on	O
widgets	O
can	O
be	O
easily	O
developed	O
using	O
the	O
dialog	B-Device
program	O
(	O
based	O
on	O
ncurses	B-Language
)	O
,	O
or	O
the	O
Whiptail	B-Language
program	O
(	O
based	O
on	O
S-Lang	B-Device
)	O
.	O
</s>
<s>
In	O
addition	O
,	O
the	O
rise	O
in	O
popularity	O
of	O
Linux	B-Application
brought	O
many	O
former	O
DOS	B-Device
users	O
to	O
a	O
Unix-like	B-Operating_System
platform	O
,	O
which	O
has	O
fostered	O
a	O
DOS	B-Device
influence	O
in	O
many	O
TUIs	O
.	O
</s>
<s>
The	O
program	O
minicom	B-Language
,	O
for	O
example	O
,	O
is	O
modeled	O
after	O
the	O
popular	O
DOS	B-Device
program	O
Telix	B-Protocol
.	O
</s>
<s>
Most	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
(	O
Linux	B-Application
,	O
FreeBSD	B-Operating_System
,	O
etc	O
.	O
)	O
</s>
<s>
support	O
virtual	B-Application
consoles	I-Application
,	O
typically	O
accessed	O
through	O
a	O
Ctrl-Alt-F	O
key	O
combination	O
.	O
</s>
<s>
For	O
example	O
,	O
under	O
Linux	B-Application
up	O
to	O
64	O
consoles	O
may	O
be	O
accessed	O
(	O
12	O
via	O
function	B-Application
keys	I-Application
)	O
,	O
each	O
displaying	O
in	O
full-screen	O
text	B-Application
mode	I-Application
.	O
</s>
<s>
The	O
free	B-Application
software	I-Application
program	O
GNU	B-Application
Screen	I-Application
provides	O
for	O
managing	O
multiple	O
sessions	O
inside	O
a	O
single	O
TUI	O
,	O
and	O
so	O
can	O
be	O
thought	O
of	O
as	O
being	O
like	O
a	O
window	B-Application
manager	I-Application
for	O
text-mode	B-Application
and	O
command-line	B-Application
interfaces	I-Application
.	O
</s>
<s>
Tmux	B-Language
can	O
also	O
do	O
this	O
.	O
</s>
<s>
The	O
proprietary	O
macOS	B-Application
text	B-Application
editor	I-Application
BBEdit	B-Operating_System
includes	O
a	O
shell	O
worksheet	O
function	O
that	O
works	O
as	O
a	O
full-screen	O
shell	O
window	O
.	O
</s>
<s>
The	O
free	B-Application
Emacs	B-Application
text	B-Application
editor	I-Application
can	O
run	O
a	O
shell	O
inside	O
of	O
one	O
of	O
its	O
buffers	O
to	O
provide	O
similar	O
functionality	O
.	O
</s>
<s>
There	O
are	O
several	O
shell	O
implementations	O
in	O
Emacs	B-Application
,	O
but	O
only	O
ansi-term	O
is	O
suitable	O
for	O
running	O
TUI	O
programs	O
.	O
</s>
<s>
The	O
other	O
common	O
shell	O
modes	O
,	O
shell	O
and	O
eshell	O
only	O
emulate	O
command	B-Application
lines	I-Application
and	O
TUI	O
programs	O
will	O
complain	O
"	O
Terminal	O
is	O
not	O
fully	O
functional	O
"	O
or	O
display	O
a	O
garbled	O
interface	O
.	O
</s>
<s>
The	O
free	B-Application
Vim	B-Application
and	O
Neovim	O
text	B-Application
editors	I-Application
have	O
terminal	B-Application
windows	I-Application
(	O
simulating	O
xterm	B-Language
)	O
.	O
</s>
<s>
VAX/VMS	B-Operating_System
(	O
later	O
known	O
as	O
OpenVMS	B-Operating_System
)	O
had	O
a	O
similar	O
facility	O
to	O
curses	B-Device
known	O
as	O
the	O
Screen	B-Device
Management	O
facility	O
or	O
SMG	O
.	O
</s>
<s>
This	O
could	O
be	O
invoked	O
from	O
the	O
command	B-Application
line	I-Application
or	O
called	O
from	O
programs	O
using	O
the	O
SMG$	O
library	B-Library
.	O
</s>
<s>
Another	O
kind	O
of	O
TUI	O
is	O
the	O
primary	O
interface	O
of	O
the	O
Oberon	B-Application
operating	I-Application
system	I-Application
,	O
first	O
released	O
in	O
1988	O
and	O
still	O
maintained	O
.	O
</s>
<s>
Unlike	O
most	O
other	O
text-based	B-Application
user	I-Application
interfaces	I-Application
,	O
Oberon	B-Application
does	O
not	O
use	O
a	O
text-mode	B-Application
console	O
or	O
terminal	O
,	O
but	O
requires	O
a	O
large	O
bit-mapped	O
display	O
,	O
on	O
which	O
text	O
is	O
the	O
primary	O
target	O
for	O
mouse	B-Device
clicks	O
.	O
</s>
<s>
Text	O
displayed	O
anywhere	O
on	O
the	O
screen	B-Device
can	O
be	O
edited	O
,	O
and	O
if	O
formatted	O
with	O
the	O
required	O
command	O
syntax	O
,	O
can	O
be	O
middle-clicked	O
and	O
executed	O
.	O
</s>
<s>
This	O
approach	O
is	O
radically	O
different	O
from	O
both	O
conventional	O
dialogue-oriented	O
console	O
menus	O
or	O
command	B-Application
line	I-Application
interfaces	I-Application
.	O
</s>
<s>
Since	O
it	O
does	O
not	O
use	O
graphical	O
widgets	O
,	O
only	O
plain	O
text	O
,	O
but	O
offers	O
comparable	O
functionality	O
to	O
a	O
GUI	B-Application
with	O
a	O
tiling	O
window	B-Application
manager	I-Application
,	O
it	O
is	O
referred	O
to	O
as	O
a	O
Text	B-Application
User	I-Application
Interface	I-Application
or	O
TUI	O
.	O
</s>
<s>
For	O
a	O
short	O
introduction	O
,	O
see	O
the	O
2nd	O
paragraph	O
on	O
page	O
four	O
of	O
the	O
first	O
published	O
Report	O
on	O
the	O
Oberon	B-Application
System	I-Application
.	O
</s>
<s>
Oberon	B-Application
's	O
UI	B-Application
influenced	O
the	O
design	O
of	O
the	O
Acme	B-Application
text	I-Application
editor	I-Application
and	I-Application
email	I-Application
client	I-Application
for	O
the	O
Plan	B-Operating_System
9	I-Operating_System
from	I-Operating_System
Bell	I-Operating_System
Labs	I-Operating_System
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Modern	O
embedded	B-Architecture
systems	I-Architecture
are	O
capable	O
of	O
displaying	O
TUI	O
on	O
a	O
monitor	O
like	O
personal	B-Device
computers	I-Device
.	O
</s>
<s>
This	O
functionality	O
is	O
usually	O
implemented	O
using	O
specialized	O
integrated	O
circuits	O
,	O
modules	O
,	O
or	O
using	O
FPGA	B-Architecture
.	O
</s>
<s>
Video	O
circuits	O
or	O
modules	O
are	O
usually	O
controlled	O
using	O
VT100-compatible	O
command	O
set	O
over	O
UART	O
,	O
FPGA	B-Architecture
designs	O
usually	O
allow	O
direct	O
video	O
memory	O
access	O
.	O
</s>
<s>
The	O
full	B-Application
screen	I-Application
editor	I-Application
of	O
the	O
Commodore	O
64	O
8-bit	O
computers	O
was	O
advanced	O
in	O
its	O
market	O
segment	O
for	O
its	O
time	O
.	O
</s>
<s>
Users	O
could	O
move	O
the	O
cursor	O
over	O
the	O
entire	O
screen	B-Device
area	O
,	O
entering	O
and	O
editing	O
BASIC	O
program	O
lines	O
,	O
as	O
well	O
as	O
direct	B-Application
mode	I-Application
commands	O
.	O
</s>
<s>
All	O
Commodore	O
8-bit	O
computers	O
used	O
the	O
PETSCII	B-Protocol
character	O
set	O
,	O
which	O
included	O
character	O
glyphs	O
suitable	O
for	O
making	O
a	O
TUI	O
.	O
</s>
<s>
Apple	O
's	O
Macintosh	B-Operating_System
Programmer	I-Operating_System
's	I-Operating_System
Workshop	I-Operating_System
programming	O
environment	O
included	O
Commando	O
,	O
a	O
TUI	O
shell	O
.	O
</s>
<s>
It	O
was	O
the	O
inspiration	O
for	O
BBEdit	B-Operating_System
's	O
shell	O
worksheet	O
.	O
</s>
<s>
Later	O
Apple	B-Device
II	I-Device
models	O
included	O
MouseText	B-Device
,	O
a	O
set	O
of	O
graphical	O
glyphs	O
used	O
for	O
making	O
a	O
TUI	O
.	O
</s>
