<s>
and	O
RT-11	B-Operating_System
)	O
,	O
and	O
later	O
for	O
its	O
OpenVMS	B-Operating_System
operating	O
system	O
.	O
</s>
<s>
It	O
can	O
respond	O
to	O
single	O
keystrokes	O
,	O
and	O
uses	O
function	B-Application
keys	I-Application
to	O
implement	O
commands	O
to	O
the	O
editor	O
.	O
</s>
<s>
EDT	B-Application
was	O
introduced	O
originally	O
as	O
a	O
line-mode	O
editor	O
.	O
</s>
<s>
The	O
screen	O
mode	O
was	O
developed	O
first	O
as	O
the	O
Keyboard	O
Editor	O
(	O
KED	O
)	O
on	O
RT-11	B-Operating_System
as	O
part	O
of	O
the	O
FMS-11	O
project	O
by	O
Darrell	O
Duffy	O
;	O
EDT	B-Application
on	O
the	O
other	O
operating	O
systems	O
was	O
then	O
enhanced	O
to	O
be	O
compatible	O
with	O
KED	O
.	O
</s>
<s>
As	O
with	O
many	O
user	O
interfaces	O
developed	O
around	O
this	O
time	O
,	O
EDT	B-Application
uses	O
the	O
"	O
Gold	B-Device
Key	I-Device
"	O
style	O
of	O
input	O
first	O
developed	O
for	O
the	O
WPS-8	B-Protocol
word	O
processing	O
system	O
.	O
</s>
<s>
"	O
Gold	B-Device
Key	I-Device
"	O
editing	O
uses	O
the	O
PF1	O
keypad	O
key	O
as	O
a	O
prefix	O
key	O
allowing	O
the	O
introduction	O
of	O
a	O
wide	O
variety	O
of	O
commands	O
using	O
both	O
the	O
keypad	O
keys	O
and	O
keys	O
on	O
the	O
main	O
keyboard	O
.	O
</s>
<s>
Users	O
can	O
configure	O
default	O
actions	O
or	O
define	O
key	O
sequences	O
for	O
their	O
editor	O
by	O
placing	O
EDT	B-Application
commands	O
in	O
an	O
initialization	O
file	O
which	O
is	O
executed	O
upon	O
starting	O
the	O
editor	O
.	O
</s>
<s>
DEC	O
later	O
developed	O
TPU	B-Language
,	O
a	O
powerful	O
language	O
for	O
designing	O
text	B-Application
editors	I-Application
on	O
its	O
VMS	B-Operating_System
systems	O
.	O
</s>
<s>
TPU	B-Language
was	O
used	O
to	O
produce	O
a	O
new	O
standard	O
text	B-Application
editor	I-Application
,	O
EVE	B-Application
,	O
as	O
well	O
as	O
to	O
rewrite	O
EDT	B-Application
.	O
</s>
<s>
EVE	B-Application
included	O
an	O
emulator	O
of	O
the	O
EDT	B-Application
screen	O
mode	O
keypad	O
for	O
the	O
benefit	O
of	O
those	O
who	O
were	O
used	O
to	O
particular	O
key	O
functions	O
.	O
</s>
<s>
Both	O
EVE	B-Application
and	O
the	O
TPU	B-Language
implementation	O
of	O
EDT	B-Application
are	O
still	O
distributed	O
with	O
OpenVMS	B-Operating_System
.	O
</s>
<s>
Text	B-Application
editors	I-Application
based	O
on	O
the	O
EDT	B-Application
user	O
interface	O
have	O
been	O
developed	O
for	O
other	O
systems	O
,	O
including	O
for	O
instance	O
sedt	O
,	O
an	O
EDT-based	O
editor	O
for	O
Unix	B-Application
systems	I-Application
.	O
</s>
