<s>
FlexOS	B-Operating_System
is	O
a	O
discontinued	O
modular	O
real-time	O
multiuser	O
multitasking	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
(	O
RTOS	B-Operating_System
)	O
designed	O
for	O
computer-integrated	O
manufacturing	O
,	O
laboratory	O
,	O
retail	O
and	O
financial	O
markets	O
.	O
</s>
<s>
Developed	O
by	O
Digital	O
Research	O
's	O
Flexible	O
Automation	O
Business	O
Unit	O
in	O
Monterey	O
,	O
California	O
,	O
in	O
1985	O
,	O
the	O
system	O
was	O
considered	O
to	O
become	O
a	O
successor	O
of	O
Digital	O
Research	O
's	O
earlier	O
Concurrent	B-Operating_System
DOS	I-Operating_System
,	O
but	O
with	O
a	O
new	O
,	O
modular	O
,	O
and	O
considerably	O
different	O
system	O
architecture	O
and	O
portability	O
across	O
several	O
processor	O
families	O
.	O
</s>
<s>
Still	O
named	O
Concurrent	B-Operating_System
DOS	I-Operating_System
68K	I-Operating_System
and	O
Concurrent	B-Operating_System
DOS	I-Operating_System
286	I-Operating_System
,	O
it	O
was	O
renamed	O
into	O
FlexOS	B-Operating_System
on	O
1	O
October	O
1986	O
to	O
better	O
differentiate	O
the	O
target	O
audiences	O
.	O
</s>
<s>
FlexOS	B-Operating_System
was	O
licensed	O
by	O
several	O
OEMs	O
who	O
selected	O
it	O
as	O
the	O
basis	O
for	O
their	O
own	O
operating	O
systems	O
like	O
4680	O
OS	O
,	O
4690	B-Language
OS	I-Language
,	O
S5-DOS/MT	O
and	O
others	O
.	O
</s>
<s>
Unrelated	O
to	O
FlexOS	B-Operating_System
,	O
the	O
original	O
Concurrent	B-Operating_System
DOS	I-Operating_System
system	O
architecture	O
found	O
a	O
continuation	O
in	O
successors	O
like	O
Concurrent	B-Operating_System
DOS	I-Operating_System
XM	I-Operating_System
and	O
Concurrent	B-Operating_System
DOS	I-Operating_System
386	I-Operating_System
as	O
well	O
.	O
</s>
<s>
Concurrent	B-Operating_System
DOS	I-Operating_System
286	I-Operating_System
,	O
Concurrent	B-Operating_System
DOS	I-Operating_System
68K	I-Operating_System
and	O
FlexOS	B-Operating_System
were	O
designed	O
by	O
Francis	O
"	O
Frank	O
"	O
R	O
.	O
Holsworth	O
(	O
using	O
siglum	O
FRH	O
)	O
.	O
</s>
<s>
Like	O
Portable	B-Operating_System
CP/M	I-Operating_System
,	O
Concurrent	B-Operating_System
DOS	I-Operating_System
286	I-Operating_System
,	O
Concurrent	B-Operating_System
DOS	I-Operating_System
68K	I-Operating_System
and	O
Concurrent	B-Operating_System
DOS	I-Operating_System
V60	I-Operating_System
,	O
FlexOS	B-Operating_System
was	O
written	O
in	O
C	B-Language
for	O
higher	O
portability	O
across	O
hardware	O
platforms	O
,	O
and	O
it	O
featured	O
very	O
low	O
interrupt	O
latency	O
and	O
fast	O
context	O
switching	O
.	O
</s>
<s>
The	O
original	O
protected	B-Application
mode	I-Application
FlexOS	B-Operating_System
286	I-Operating_System
version	O
1.3	O
was	O
designed	O
for	O
host	O
machines	O
equipped	O
with	O
286	B-General_Concept
CPUs	O
,	O
and	O
with	O
adaptations	O
for	O
NEC	B-Device
V60	I-Device
,	O
NEC	B-Device
V70	I-Device
and	O
Motorola	B-Device
68000	I-Device
processors	I-Device
planned	O
.	O
</s>
<s>
FlexOS	B-Operating_System
286	I-Operating_System
executables	O
using	O
the	O
system	O
's	O
native	O
INT	O
DCh	O
(	O
INT	O
220	O
)	O
application	B-Application
program	I-Application
interface	I-Application
had	O
the	O
filename	O
extension	O
.286	B-Operating_System
.	O
</s>
<s>
A	O
CP/M	B-Application
API	B-Application
front-end	O
(	O
FE	O
)	O
was	O
available	O
as	O
well	O
,	O
using	O
the	O
extension	O
.CMD	O
for	O
executables	O
.	O
</s>
<s>
(	O
A	O
filename	O
extension	O
of	O
.68K	B-Operating_System
was	O
reserved	O
for	O
FlexOS	B-Operating_System
68K	I-Operating_System
,	O
a	O
file	O
extension	O
derived	O
from	O
Concurrent	B-Operating_System
DOS	I-Operating_System
68K	I-Operating_System
as	O
of	O
1986	O
.	O
)	O
</s>
<s>
In	O
May	O
1987	O
,	O
FlexOS	B-Operating_System
version	O
1.31	O
was	O
released	O
for	O
80286	B-General_Concept
machines	O
.	O
</s>
<s>
The	O
developer	O
version	O
required	O
an	O
IBM	B-Operating_System
PC/AT	I-Operating_System
-compatible	O
machine	O
with	O
640KB	O
of	O
conventional	B-Device
and	O
512KB	O
of	O
extended	B-Device
memory	I-Device
,	O
and	O
either	O
a	O
(	O
monochrome	O
)	O
CGA	O
or	O
an	O
EGA	O
graphics	O
adapter	O
.	O
</s>
<s>
FlexOS	B-Operating_System
supported	O
a	O
concept	O
of	O
dynamically	B-Operating_System
loadable	I-Operating_System
and	O
unloadable	O
subdrivers	O
,	O
and	O
it	O
came	O
with	O
driver	O
prototypes	O
for	O
floppies	O
,	O
hard	O
disks	O
,	O
printers	O
,	O
serial	O
interfaces	O
,	O
RAM	O
disks	O
,	O
mice	O
and	O
console	O
drivers	O
.	O
</s>
<s>
During	O
boot	O
,	O
the	O
FLEX286.SYS	B-Operating_System
kernel	O
would	O
load	O
the	O
resource	O
managers	O
and	O
device	O
drivers	O
specified	O
in	O
the	O
CONFIG.SYS	B-Device
binary	O
file	O
(	O
not	O
to	O
be	O
mixed	O
up	O
with	O
the	O
similarly	O
named	O
CONFIG.SYS	B-Device
configuration	O
file	O
under	O
DOS	B-Device
)	O
,	O
and	O
its	O
shell	O
(	O
COMMAND.286	O
)	O
would	O
execute	O
a	O
CONFIG.BAT	B-Operating_System
startup	O
batch	O
job	O
instead	O
of	O
the	O
common	O
AUTOEXEC.BAT	O
.	O
</s>
<s>
FlexOS	B-Operating_System
's	O
optional	O
DOS	B-Device
emulator	O
provided	O
limited	O
PC	O
DOS	B-Device
2.1	O
compatibility	O
for	O
DOS	B-Device
.COM	O
and	O
.EXE	O
programs	O
.	O
</s>
<s>
Certain	O
restrictions	O
applied	O
in	O
"	O
8086	B-Operating_System
emulation	I-Operating_System
mode	I-Operating_System
"	O
since	O
these	O
programs	O
were	O
executed	O
in	O
the	O
processor	O
's	O
protected	B-Application
mode	I-Application
.	O
</s>
<s>
Due	O
to	O
bugs	O
in	O
earlier	O
steppings	O
of	O
the	O
Intel	B-General_Concept
80286	I-General_Concept
,	O
the	O
FlexOS	B-Operating_System
286	I-Operating_System
DOS	B-Device
front-end	O
required	O
at	O
least	O
the	O
80286	B-General_Concept
E2	O
stepping	O
to	O
function	O
properly	O
(	O
see	O
LOADALL	B-Device
)	O
.	O
</s>
<s>
These	O
problems	O
had	O
already	O
caused	O
delays	O
in	O
the	O
delivery	O
of	O
Concurrent	B-Operating_System
DOS	I-Operating_System
286	I-Operating_System
earlier	O
.	O
</s>
<s>
The	O
system	O
optionally	O
supported	O
a	O
multitasking	B-Operating_System
GEM	B-Application
VDI	O
for	O
graphical	O
applications	O
.	O
</s>
<s>
FlexOS	B-Operating_System
1.31	O
could	O
be	O
linked	O
with	O
none	O
,	O
either	O
or	O
both	O
of	O
these	O
two	O
modules	O
.	O
</s>
<s>
FlexOS	B-Operating_System
1.31	O
also	O
supported	O
FlexNet	O
.	O
</s>
<s>
By	O
June	O
1987	O
there	O
were	O
also	O
versions	O
1.0	O
of	O
FlexOS	B-Operating_System
386	B-General_Concept
(	O
for	O
hosts	O
)	O
and	O
FlexOS	B-Operating_System
186	B-Device
(	O
for	O
remote	O
cell	O
controllers	O
)	O
.	O
</s>
<s>
FlexOS	B-Operating_System
386	B-General_Concept
provided	O
a	O
windowing	O
feature	O
,	O
and	O
offered	O
PC	O
DOS	B-Device
3.2	O
and	O
GEM	B-Application
compatibility	O
.	O
</s>
<s>
Among	O
the	O
major	O
FlexOS	B-Operating_System
customers	O
in	O
1990/1991	O
were	O
FANUC	O
,	O
IBM	O
,	O
ICL	O
,	O
Nixdorf	O
,	O
Siemens	O
,	O
TEC	O
,	O
Thorn	O
EMI	O
Software	O
and	O
Micrologic	O
.	O
</s>
<s>
X/GEM	B-Application
for	O
FlexOS	B-Operating_System
release	O
1.0	O
(	O
a.k.a.	O
</s>
<s>
X/GEM	B-Application
FlexOS	B-Operating_System
286	I-Operating_System
and	O
386	B-General_Concept
)	O
and	O
FlexNet	O
were	O
registered	O
on	O
21	O
December	O
1992	O
.	O
</s>
<s>
FlexOS	B-Operating_System
was	O
used	O
as	O
the	O
primary	O
test	O
platform	O
for	O
the	O
new	O
Novell	B-Application
Embedded	I-Application
Systems	I-Application
Technology	I-Application
(	O
NEST	B-Application
)	O
.	O
</s>
<s>
When	O
Novell	O
decided	O
to	O
abandon	O
further	O
development	O
of	O
the	O
various	O
Digital	O
Research	O
operating	O
systems	O
such	O
as	O
Multiuser	B-Operating_System
DOS	I-Operating_System
(	O
a	O
successor	O
to	O
Concurrent	B-Operating_System
DOS	I-Operating_System
)	O
and	O
Novell	B-Operating_System
DOS	I-Operating_System
(	O
a	O
successor	O
to	O
DR	O
DOS	B-Device
)	O
,	O
they	O
sold	O
FlexOS	B-Operating_System
off	O
to	O
the	O
Santa	O
Clara	O
,	O
California-based	O
Integrated	O
Systems	O
Inc	O
.	O
(	O
ISI	O
)	O
for	O
million	O
in	O
July	O
1994	O
.	O
</s>
<s>
The	O
company	O
already	O
had	O
pSOS+	B-Operating_System
,	O
another	O
modular	O
real-time	O
multitasking	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
for	O
embedded	O
systems	O
,	O
but	O
they	O
continued	O
to	O
maintain	O
FlexOS	B-Operating_System
as	O
well	O
.	O
</s>
<s>
FlexOS	B-Operating_System
version	O
2.33	O
was	O
current	O
as	O
of	O
May	O
1998	O
and	O
with	O
FlexOS	B-Operating_System
2.34	O
to	O
be	O
released	O
soon	O
after	O
with	O
added	O
support	O
for	O
faster	O
CPUs	O
,	O
64	O
MB	O
of	O
memory	O
,	O
EIDE	O
and	O
ATAPI	O
CDROM	O
drives	O
.	O
</s>
<s>
The	O
following	O
list	O
of	O
commands	B-Application
is	O
supported	O
by	O
FlexOS	B-Operating_System
:	O
</s>
<s>
Known	O
FlexOS	B-Operating_System
versions	O
include	O
:	O
</s>
<s>
Motorola	B-Device
68000	I-Device
/	O
Freescale/NXP	O
ColdFire	O
MCF5251	O
platform	O
:	O
</s>
<s>
FlexOS	B-Operating_System
68K	I-Operating_System
1.x	O
?	O
</s>
<s>
Intel	B-General_Concept
80286	I-General_Concept
platform	O
:	O
</s>
<s>
Intel	B-General_Concept
80386	I-General_Concept
platform	O
:	O
</s>
<s>
FlexOS	B-Operating_System
386	B-General_Concept
2.30	O
?	O
</s>
<s>
FlexOS	B-Operating_System
386	B-General_Concept
2.31	O
?	O
</s>
<s>
NEC	B-Device
V60	I-Device
platform	O
:	O
</s>
<s>
Concurrent	B-Operating_System
DOS	I-Operating_System
V60	I-Operating_System
?	O
</s>
<s>
Named	O
IBM	O
4680	O
OS	O
Version	O
1	O
,	O
IBM	O
originally	O
chose	O
DR	O
Concurrent	B-Operating_System
DOS	I-Operating_System
286	I-Operating_System
as	O
the	O
basis	O
of	O
their	O
IBM	O
4680	O
computer	O
for	O
IBM	O
Plant	O
System	O
products	O
and	O
Point-of-Sale	O
terminals	O
in	O
1986	O
.	O
</s>
<s>
In	O
July	O
1993	O
,	O
IBM	O
announced	O
the	O
adoption	O
of	O
FlexOS	B-Operating_System
version	O
2.32	O
as	O
the	O
basis	O
of	O
their	O
IBM	B-Language
4690	I-Language
OS	I-Language
Version	O
1	O
,	O
to	O
be	O
pre-released	O
on	O
24	O
September	O
1993	O
and	O
generally	O
made	O
available	O
from	O
25	O
March	O
1994	O
.	O
</s>
<s>
FlexOS	B-Operating_System
2.32	O
supported	O
286	B-General_Concept
and	O
386	B-General_Concept
modes	O
,	O
had	O
more	B-Device
efficient	O
memory	O
management	O
,	O
better	O
console	O
and	O
pipe	O
systems	O
,	O
and	O
brought	O
overall	O
quality	O
and	O
performance	O
improvements	O
compared	O
to	O
the	O
version	O
that	O
came	O
with	O
IBM	O
4680	O
OS	O
Version	O
4	O
.	O
</s>
<s>
Further	O
,	O
it	O
removed	O
limits	O
on	O
the	O
number	O
of	O
applications	O
running	O
concurrently	O
due	O
to	O
its	O
more	B-Device
efficient	O
use	O
of	O
KOSPOOL	O
.	O
</s>
<s>
To	O
support	O
Java	B-Language
,	O
IBM	B-Language
4690	I-Language
OS	I-Language
Version	O
2	O
added	O
support	O
for	O
long	O
filenames	O
by	O
means	O
of	O
a	O
virtual	B-Application
filesystem	I-Application
(	O
VFS	O
)	O
architecture	O
and	O
it	O
introduced	O
FAT32	B-Application
volumes	O
.	O
</s>
<s>
"	O
,	O
IHL	O
Consulting	O
Group/RIS	O
News	O
,	O
IBM	B-Language
4690	I-Language
OS	I-Language
still	O
had	O
a	O
market	O
share	O
of	O
12%	O
in	O
the	O
POS	O
register/client	O
market	O
in	O
June	O
2005	O
,	O
when	O
IBM	O
was	O
starting	O
to	O
phase	O
it	O
out	O
in	O
favour	O
to	O
IBM	O
Retail	O
Environment	O
for	O
SUSE	O
(	O
IRES	O
)	O
.	O
</s>
<s>
IBM	O
continued	O
to	O
maintain	O
4690	B-Language
OS	I-Language
up	O
to	O
April	O
2015	O
,	O
with	O
the	O
most	O
recent	O
version	O
released	O
by	O
IBM	O
in	O
May	O
2012	O
being	O
IBM	B-Language
4690	I-Language
OS	I-Language
Version	O
6	O
Release	O
3	O
.	O
</s>
<s>
Toshiba	O
released	O
Toshiba	B-Language
4690	I-Language
OS	I-Language
Version	O
6	O
Release	O
4	O
in	O
January	O
2014	O
and	O
Version	O
6	O
Release	O
5	O
in	O
January	O
2016	O
.	O
</s>
<s>
Siemens	O
used	O
and	O
still	O
maintains	O
FlexOS	B-Operating_System
in	O
their	O
factory	O
automation	O
equipment	O
as	O
well	O
.	O
</s>
<s>
For	O
example	O
,	O
their	O
Simatic	O
S5	O
STEP-5	O
operating	O
system	O
S5-DOS/MT	O
is	O
based	O
on	O
FlexOS	B-Operating_System
386	B-General_Concept
with	O
X/GEM	B-Application
,	O
FlexNet	O
and	O
Btrieve	B-Application
,	O
whereas	O
the	O
smaller	O
S5-DOS	B-Operating_System
system	O
,	O
also	O
present	O
on	O
these	O
systems	O
,	O
is	O
a	O
variant	O
of	O
Digital	O
Research	O
's	O
Personal	B-Operating_System
CP/M	I-Operating_System
-86	I-Operating_System
.	O
</s>
<s>
Siemens	O
industrial	O
systems	O
like	O
COROS	O
LS-B/FlexOS	O
,	O
COROS	O
OS-B/FlexOS	O
,	O
GRACIS/FlexOS	O
,	O
OS-525	O
were	O
FlexOS	B-Operating_System
and	O
X/GEM	B-Application
-based	O
.	O
</s>
<s>
Computers	O
such	O
as	O
the	O
PC	O
16-20	O
and	O
the	O
PC	O
32	O
series	O
were	O
available	O
with	O
FlexOS	B-Operating_System
as	O
well	O
.	O
</s>
<s>
The	O
Japanese	O
post	O
office	O
shared	O
terminals	O
III	O
and	O
CTM	O
IV	O
were	O
based	O
on	O
FlexOS	B-Operating_System
.	O
</s>
