<s>
Digital	O
Research	O
,	O
Inc	O
.	O
(	O
DR	O
or	O
DRI	O
)	O
was	O
a	O
privately	O
held	O
American	O
software	O
company	O
created	O
by	O
Gary	O
Kildall	O
to	O
market	O
and	O
develop	O
his	O
CP/M	B-Application
operating	I-Application
system	I-Application
and	O
related	O
8-bit	O
,	O
16-bit	O
and	O
32-bit	O
systems	O
like	O
MP/M	B-Operating_System
,	O
Concurrent	B-Operating_System
DOS	I-Operating_System
,	O
FlexOS	B-Operating_System
,	O
Multiuser	B-Operating_System
DOS	I-Operating_System
,	O
DOS	B-Operating_System
Plus	I-Operating_System
,	O
DR	O
DOS	O
and	O
GEM	B-Application
.	O
</s>
<s>
It	O
was	O
the	O
first	O
large	O
software	O
company	O
in	O
the	O
microcomputer	B-Architecture
world	O
.	O
</s>
<s>
In	O
1972	O
,	O
Gary	O
Kildall	O
,	O
an	O
instructor	O
at	O
the	O
Naval	O
Postgraduate	O
School	O
in	O
Monterey	O
,	O
California	O
,	O
began	O
working	O
at	O
Intel	O
as	O
a	O
consultant	O
under	O
the	O
business	O
name	O
Microcomputer	B-Architecture
Applications	O
Associates	O
(	O
MAA	O
)	O
.	O
</s>
<s>
By	O
1974	O
,	O
he	O
had	O
developed	O
Control	B-Application
Program/Monitor	I-Application
,	O
or	O
CP/M	B-Application
,	O
the	O
first	O
disk	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
for	O
microcomputers	B-Architecture
.	O
</s>
<s>
The	O
company	O
's	O
operating	B-General_Concept
systems	I-General_Concept
,	O
starting	O
with	O
CP/M	B-Application
for	O
8080/Z80	O
-based	O
microcomputers	B-Architecture
,	O
were	O
the	O
de	O
facto	O
standard	O
of	O
their	O
era	O
.	O
</s>
<s>
Digital	O
Research	O
's	O
product	O
suite	O
included	O
the	O
original	O
8-bit	O
CP/M	B-Application
and	O
its	O
various	O
offshoots	O
like	O
MP/M	B-Operating_System
(	O
1979	O
)	O
,	O
a	O
multi-tasking	O
multi-user	O
version	O
of	O
CP/M	B-Application
.	O
</s>
<s>
The	O
first	O
16-bit	O
system	O
was	O
CP/M	B-Operating_System
-86	I-Operating_System
(	O
1981	O
,	O
adapted	O
to	O
the	O
IBM	B-Device
PC	I-Device
in	O
early	O
1982	O
)	O
,	O
which	O
was	O
meant	O
as	O
direct	O
competitor	O
to	O
MS-DOS	B-Application
.	O
</s>
<s>
There	O
followed	O
the	O
multi-tasking	O
MP/M	B-Operating_System
-86	I-Operating_System
(	O
1981	O
)	O
,	O
and	O
Concurrent	B-Operating_System
CP/M	I-Operating_System
(	O
1982	O
)	O
,	O
a	O
single-user	O
version	O
featuring	O
virtual	O
consoles	O
from	O
which	O
applications	O
could	O
be	O
launched	O
to	O
run	O
concurrently	O
.	O
</s>
<s>
It	O
remained	O
influential	O
,	O
with	O
million	O
in	O
1983	O
sales	O
making	O
Digital	O
Research	O
the	O
fourth-largest	O
microcomputer	B-Architecture
software	O
company	O
.	O
</s>
<s>
Admitting	O
that	O
it	O
had	O
"	O
lost	O
"	O
the	O
8088	B-Device
software	O
market	O
but	O
hoped	O
to	O
succeed	O
with	O
the	O
Intel	B-General_Concept
80286	I-General_Concept
and	O
Motorola	B-Device
68000	I-Device
,	O
by	O
1984	O
the	O
company	O
formed	O
a	O
partnership	O
with	O
AT&T	O
Corporation	O
to	O
develop	O
software	O
for	O
Unix	B-Operating_System
System	I-Operating_System
V	I-Operating_System
and	O
sell	O
its	O
own	O
and	O
third-party	O
products	O
in	O
retail	O
stores	O
.	O
</s>
<s>
Successive	O
revisions	O
of	O
Concurrent	B-Operating_System
CP/M	I-Operating_System
incorporated	O
MS-DOS	B-Application
API	B-Application
emulation	O
(	O
since	O
1983	O
)	O
,	O
which	O
gradually	O
added	O
more	O
support	O
for	O
DOS	O
applications	O
and	O
the	O
FAT	B-Application
file	I-Application
system	I-Application
.	O
</s>
<s>
These	O
versions	O
were	O
named	O
Concurrent	B-Operating_System
DOS	I-Operating_System
(	O
1984	O
)	O
,	O
with	O
Concurrent	O
PC	O
DOS	O
(	O
1984	O
)	O
being	O
the	O
version	O
adapted	O
to	O
run	O
on	O
IBM	O
compatible	O
PCs	O
.	O
</s>
<s>
In	O
1985	O
,	O
soon	O
after	O
the	O
introduction	O
of	O
the	O
80286-based	O
IBM	B-Operating_System
PC/AT	I-Operating_System
,	O
Digital	O
Research	O
introduced	O
a	O
real-time	O
system	O
,	O
initially	O
called	O
Concurrent	B-Operating_System
DOS	I-Operating_System
286	I-Operating_System
,	O
which	O
later	O
evolved	O
into	O
the	O
modular	O
FlexOS	B-Operating_System
(	O
1986	O
)	O
.	O
</s>
<s>
This	O
exploited	O
the	O
greater	O
memory	O
addressing	O
capability	O
of	O
the	O
new	O
CPU	B-Device
to	O
provide	O
a	O
more	O
flexible	O
multi-tasking	O
environment	O
.	O
</s>
<s>
There	O
was	O
a	O
small	O
but	O
powerful	O
set	O
of	O
system	O
APIs	B-Application
,	O
each	O
with	O
a	O
synchronous	O
and	O
an	O
asynchronous	O
variant	O
.	O
</s>
<s>
Other	O
successors	O
of	O
Concurrent	B-Operating_System
DOS	I-Operating_System
were	O
Concurrent	B-Operating_System
DOS	I-Operating_System
XM	I-Operating_System
(	O
1986	O
)	O
and	O
the	O
32-bit	O
Concurrent	B-Operating_System
DOS	I-Operating_System
386	I-Operating_System
(	O
1987	O
)	O
,	O
and	O
finally	O
Multiuser	B-Operating_System
DOS	I-Operating_System
(	O
1991	O
)	O
.	O
</s>
<s>
Digital	O
Research	O
's	O
multi-user	O
family	O
of	O
operating	B-General_Concept
systems	I-General_Concept
was	O
sidelined	O
by	O
single-user	O
offsprings	O
DOS	B-Operating_System
Plus	I-Operating_System
(	O
1985	O
)	O
and	O
DR	O
DOS	O
(	O
1988	O
)	O
.	O
</s>
<s>
The	O
latter	O
system	O
was	O
marketed	O
as	O
a	O
direct	O
MS-DOS/PC	O
DOS	O
replacement	O
with	O
added	O
functionality	O
.	O
</s>
<s>
In	O
order	O
to	O
achieve	O
this	O
,	O
it	O
gave	O
up	O
built-in	O
support	O
to	O
run	O
CP/M	B-Application
applications	O
and	O
was	O
changed	O
to	O
use	O
DOS-compatible	O
internal	O
structures	O
.	O
</s>
<s>
Digital	O
Research	O
was	O
purchased	O
by	O
Novell	O
for	O
million	O
in	O
1991	O
,	O
primarily	O
for	O
Novell	O
to	O
gain	O
access	O
to	O
the	O
operating	B-General_Concept
system	I-General_Concept
line	O
.	O
</s>
<s>
FlexOS	B-Operating_System
had	O
already	O
been	O
adopted	O
as	O
the	O
basis	O
for	O
Siemens	O
S5-DOS/MT	O
,	O
IBM	B-Language
4680	I-Language
OS	I-Language
and	O
4690	B-Language
OS	I-Language
,	O
whereas	O
Multiuser	B-Operating_System
DOS	I-Operating_System
evolved	O
further	O
into	O
independent	O
products	O
like	O
Datapac	O
System	O
Manager	O
,	O
IMS	O
REAL/32	O
and	O
REAL/NG	B-Operating_System
.	O
</s>
<s>
Continued	O
development	O
of	O
the	O
DRDOS	B-Application
line	O
led	O
to	O
non-DRI	O
products	O
such	O
as	O
Novell	O
PalmDOS	O
,	O
Novell	B-Operating_System
DOS	I-Operating_System
,	O
Caldera	B-Application
OpenDOS	I-Application
and	O
Dell	O
RMK	O
.	O
</s>
<s>
In	O
a	O
parallel	O
development	O
Digital	O
Research	O
also	O
produced	O
a	O
selection	O
of	O
programming	B-Language
language	I-Language
compilers	I-Language
and	O
interpreters	B-Application
for	O
their	O
OS-supported	O
platforms	O
,	O
including	O
C	B-Language
,	O
Pascal	B-Application
,	O
COBOL	B-Application
,	O
FORTRAN	B-Application
,	O
PL/I	B-Language
,	O
PL/M	B-Language
,	O
CBASIC	B-Language
,	O
BASIC	O
,	O
and	O
Logo	B-Device
.	O
</s>
<s>
They	O
also	O
produced	O
a	O
microcomputer	B-Architecture
version	O
of	O
the	O
GKS	O
graphics	O
standard	O
(	O
related	O
to	O
NAPLPS	B-Protocol
)	O
called	O
GSX	B-Application
,	O
and	O
later	O
used	O
this	O
as	O
the	O
basis	O
of	O
their	O
GEM	B-Application
GUI	I-Application
.	O
</s>
<s>
Less	O
known	O
are	O
their	O
application	O
programs	O
,	O
limited	O
largely	O
to	O
the	O
GSX-based	O
DR	O
DRAW	O
and	O
a	O
small	O
suite	O
of	O
GUI	B-Application
programs	O
for	O
GEM	B-Application
.	O
</s>
<s>
At	O
the	O
time	O
the	O
IBM	B-Device
Personal	I-Device
Computer	I-Device
was	O
being	O
developed	O
,	O
Digital	O
Research	O
's	O
CP/M	B-Application
was	O
the	O
dominant	O
operating	B-General_Concept
system	I-General_Concept
of	O
the	O
day	O
.	O
</s>
<s>
In	O
1980	O
,	O
IBM	O
asked	O
Digital	O
Research	O
to	O
supply	O
a	O
version	O
of	O
CP/M	B-Application
written	O
for	O
the	O
Intel	B-General_Concept
8086	I-General_Concept
microprocessor	O
as	O
the	O
standard	O
operating	B-General_Concept
system	I-General_Concept
for	O
the	O
PC	O
,	O
which	O
would	O
use	O
the	O
code-compatible	O
Intel	B-Device
8088	I-Device
chip	O
.	O
</s>
<s>
Microsoft	O
seized	O
this	O
opportunity	O
to	O
supply	O
an	O
OS	O
,	O
in	O
addition	O
to	O
other	O
software	O
(	O
e.g.	O
,	O
BASIC	O
)	O
for	O
the	O
new	O
IBM	B-Device
PC	I-Device
.	O
</s>
<s>
When	O
the	O
IBM	B-Device
PC	I-Device
arrived	O
in	O
late	O
1981	O
,	O
it	O
came	O
with	O
PC	O
DOS	O
,	O
an	O
OEM	O
version	O
of	O
MS-DOS	B-Application
,	O
which	O
was	O
developed	O
from	O
86-DOS	B-Operating_System
,	O
which	O
Microsoft	O
had	O
acquired	O
for	O
this	O
purpose	O
.	O
</s>
<s>
By	O
mid-1982	O
,	O
MS-DOS	B-Application
was	O
also	O
marketed	O
for	O
use	O
in	O
hardware-compatible	O
non-IBM	O
computers	O
.	O
</s>
<s>
Digital	O
Research	O
developed	O
CP/M	B-Operating_System
-86	I-Operating_System
as	O
an	O
alternative	O
to	O
MS-DOS	B-Application
and	O
it	O
was	O
made	O
available	O
through	O
IBM	O
in	O
early	O
1982	O
.	O
</s>
<s>
The	O
company	O
later	O
created	O
an	O
MS-DOS	B-Application
clone	O
with	O
advanced	O
features	O
called	O
DR	O
DOS	O
,	O
which	O
pressured	O
Microsoft	O
to	O
further	O
improve	O
its	O
own	O
DOS	O
.	O
</s>
<s>
The	O
competition	O
between	O
MS-DOS	B-Application
and	O
DRDOS	B-Application
is	O
one	O
of	O
the	O
more	O
controversial	O
chapters	O
of	O
microcomputer	B-Architecture
history	O
.	O
</s>
<s>
Microsoft	O
offered	O
better	O
licensing	O
terms	O
to	O
any	O
computer	O
manufacturer	O
that	O
committed	O
to	O
selling	O
MS-DOS	B-Application
with	O
every	O
system	O
they	O
shipped	O
,	O
making	O
it	O
uneconomical	O
for	O
them	O
to	O
offer	O
systems	O
with	O
another	O
OS	O
,	O
since	O
the	O
manufacturer	O
would	O
still	O
be	O
required	O
to	O
pay	O
a	O
license	O
fee	O
to	O
Microsoft	O
for	O
that	O
system	O
.	O
</s>
<s>
Digital	O
Research	O
(	O
and	O
later	O
its	O
successor	O
Caldera	O
)	O
accused	O
Microsoft	O
of	O
announcing	O
vaporware	B-Application
versions	O
of	O
MS-DOS	B-Application
to	O
suppress	O
sales	O
of	O
DRDOS	B-Application
.	O
</s>
<s>
In	O
one	O
beta	O
release	O
of	O
Windows	B-Application
3.1	I-Application
,	O
Microsoft	O
included	O
hidden	O
code	O
(	O
later	O
called	O
the	O
AARD	O
code	O
)	O
that	O
detected	O
DRDOS	B-Application
and	O
displayed	O
a	O
cryptic	O
error	O
message	O
.	O
</s>
<s>
Although	O
this	O
code	O
was	O
not	O
enabled	O
in	O
the	O
final	O
version	O
of	O
Windows	B-Application
3.1	I-Application
,	O
it	O
gave	O
the	O
wrong	O
impression	O
that	O
DRDOS	B-Application
was	O
incompatible	O
with	O
MS-DOS	B-Application
and	O
Windows	O
among	O
testers	O
.	O
</s>
<s>
These	O
activities	O
came	O
to	O
light	O
when	O
the	O
discovery	O
process	O
of	O
the	O
subsequent	O
lawsuit	O
uncovered	O
emails	O
from	O
senior	O
Microsoft	O
executives	O
that	O
showed	O
this	O
time	O
bomb	O
plant	O
was	O
part	O
of	O
a	O
concerted	O
program	O
to	O
drive	O
Digital	O
Research	O
out	O
of	O
the	O
PC	O
operating	B-General_Concept
systems	I-General_Concept
business	O
.	O
</s>
