<s>
UniFLEX	B-Operating_System
is	O
a	O
Unix-like	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
developed	O
by	O
Technical	O
Systems	O
Consultants	O
(	O
TSC	O
)	O
for	O
the	O
Motorola	B-Device
6809	I-Device
family	O
which	O
allowed	O
multitasking	B-Operating_System
and	O
multiprocessing	B-Operating_System
.	O
</s>
<s>
It	O
was	O
released	O
for	O
DMA-capable	O
8	O
"	O
floppy	O
,	O
extended	O
memory	O
addressing	O
hardware	O
(	O
software	O
controlled	O
4KiB	O
paging	O
of	O
up	O
to	O
768	O
KiB	O
RAM	O
)	O
,	O
Motorola	B-Device
6809	I-Device
based	O
computers	O
.	O
</s>
<s>
On	O
SWTPC	O
machines	O
,	O
UniFLEX	B-Operating_System
also	O
supported	O
a	O
20	O
MB	O
,	O
14	O
"	O
hard	O
drive	O
(	O
OEM	O
'd	O
from	O
Century	O
Data	O
Systems	O
)	O
in	O
1979	O
.	O
</s>
<s>
Due	O
to	O
the	O
limited	O
address	O
space	O
of	O
the	O
6809	B-Device
(	O
64	O
kB	O
)	O
and	O
hardware	O
limitations	O
,	O
the	O
main	O
memory	O
space	O
for	O
the	O
UniFLEX	B-Operating_System
kernel	O
as	O
well	O
as	O
for	O
any	O
running	O
process	O
had	O
to	O
be	O
smaller	O
than	O
56	O
kB	O
(	O
code	O
+	O
data	O
)	O
(	O
processes	O
could	O
be	O
up	O
to	O
64K	O
minus	O
512	O
bytes	O
)	O
.	O
</s>
<s>
This	O
was	O
achieved	O
by	O
writing	O
the	O
kernel	O
and	O
most	O
user	O
space	O
code	O
entirely	O
in	O
assembly	B-Language
language	I-Language
,	O
and	O
by	O
removing	O
a	O
few	O
classic	O
Unix	B-Application
features	O
,	O
such	O
as	O
group	O
permissions	O
for	O
files	O
.	O
</s>
<s>
Otherwise	O
,	O
UniFLEX	B-Operating_System
was	O
very	O
similar	O
to	O
Unix	B-Operating_System
Version	I-Operating_System
7	I-Operating_System
,	O
though	O
some	O
command	O
names	O
were	O
slightly	O
different	O
.	O
</s>
<s>
There	O
was	O
no	O
technical	O
reason	O
for	O
the	O
renaming	O
apart	O
from	O
achieving	O
some	O
level	O
of	O
command-level	O
compatibility	O
with	O
its	O
single-user	O
sibling	O
FLEX	B-Device
.	O
</s>
<s>
By	O
simply	O
restoring	O
the	O
Unix	B-Application
style	O
names	O
,	O
a	O
considerable	O
degree	O
of	O
"	O
Unix	B-Application
Look	O
&	O
Feel	O
"	O
could	O
be	O
established	O
,	O
though	O
due	O
to	O
memory	O
limitations	O
the	O
command	O
line	O
interpreter	O
(	O
shell	O
)	O
was	O
less	O
capable	O
than	O
the	O
Bourne	O
Shell	O
known	O
from	O
Unix	B-Operating_System
Version	I-Operating_System
7	I-Operating_System
.	O
</s>
<s>
However	O
UniFLEX	B-Operating_System
was	O
an	O
extremely	O
memory-efficient	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
TSC	O
never	O
bundled	O
a	O
C	B-Language
compiler	B-Language
with	O
UniFLEX	B-Operating_System
for	O
the	O
6809	B-Device
,	O
though	O
they	O
produced	O
one	O
.	O
</s>
<s>
But	O
in	O
the	O
early	O
1980s	O
a	O
C	B-Language
language	I-Language
implementation	O
became	O
available	O
as	O
a	O
3rd	O
party	O
products	O
(	O
the	O
"	O
McCosh	O
"	O
and	O
"	O
Introl	O
"	O
compilers	B-Language
)	O
.	O
</s>
<s>
Using	O
such	O
a	O
C	B-Language
compiler	B-Language
could	O
establish	O
source-level	O
compatibility	O
with	O
Unix	B-Operating_System
Version	I-Operating_System
7	I-Operating_System
,	O
i.e.	O
,	O
a	O
number	O
of	O
Unix	B-Application
tools	O
and	O
applications	O
could	O
be	O
ported	O
to	O
UniFLEX	B-Operating_System
-	O
if	O
size	O
allowed	O
:	O
Unix	B-Application
on	O
a	O
PDP-11	B-Device
limited	O
executables	O
to	O
64	O
kB	O
of	O
code	O
and	O
another	O
64	O
kB	O
of	O
data	O
,	O
while	O
the	O
UniFLEX	B-Operating_System
limitation	O
was	O
approximately	O
56	O
kB	O
for	O
both	O
,	O
code	O
and	O
data	O
together	O
.	O
</s>
<s>
Not	O
much	O
application	O
software	O
was	O
available	O
for	O
UniFLEX	B-Operating_System
.	O
</s>
<s>
Ports	O
of	O
the	O
Dynacalc	O
spreadsheet	B-Application
and	O
the	O
Stylograph	O
word	B-General_Concept
processor	I-General_Concept
from	O
the	O
FLEX	B-Device
operating	B-General_Concept
system	I-General_Concept
existed	O
but	O
only	O
very	O
few	O
copies	O
were	O
sold	O
.	O
</s>
<s>
In	O
the	O
mid	O
1980s	O
a	O
successor	O
version	O
for	O
the	O
Motorola	B-Device
68000	I-Device
was	O
announced	O
.	O
</s>
<s>
Though	O
it	O
removed	O
the	O
pressing	O
space	O
limitations	O
,	O
it	O
was	O
not	O
commercially	O
successful	O
because	O
it	O
had	O
to	O
compete	O
with	O
source-code	O
ports	O
of	O
original	O
Unix	B-Application
.	O
</s>
<s>
The	O
source	O
code	O
for	O
UniFLEX	B-Operating_System
and	O
supporting	O
software	O
is	O
available	O
on	O
the	O
Internet	O
.	O
</s>
<s>
In	O
the	O
Netherlands	O
,	O
UniFLEX	B-Operating_System
users	O
ported	O
a	O
fair	O
number	O
of	O
Unix	B-Application
utilities	O
to	O
UniFLEX	B-Operating_System
.	O
</s>
<s>
Its	O
products	O
were	O
,	O
for	O
example	O
,	O
utilities	O
that	O
allowed	O
transfer	O
of	O
data	O
between	O
UniFLEX	B-Operating_System
and	O
MS-DOS	O
and	O
vice	O
versa	O
,	O
as	O
well	O
DOS	O
format	O
utilities	O
,	O
and	O
a	O
code	O
patch	O
utility	O
.	O
</s>
