<s>
EUMEL	B-Operating_System
(	O
pronounced	O
oimel	O
for	O
Extendable	O
Multi	O
User	O
Microprocessor	O
ELAN	B-Language
System	O
and	O
also	O
known	O
as	O
L2	B-Operating_System
for	O
Liedtke	B-Operating_System
2	I-Operating_System
)	O
is	O
an	O
operating	B-General_Concept
system	I-General_Concept
(	O
OS	O
)	O
which	O
began	O
as	O
a	O
runtime	B-Device
system	I-Device
(	O
environment	O
)	O
for	O
the	O
programming	O
language	O
ELAN	B-Language
.	O
</s>
<s>
EUMEL	B-Operating_System
initially	O
ran	O
on	O
the	O
8-bit	O
Zilog	B-General_Concept
Z80	I-General_Concept
processor	O
.	O
</s>
<s>
It	O
later	O
was	O
ported	O
to	O
many	O
different	O
computer	B-General_Concept
architectures	I-General_Concept
.	O
</s>
<s>
More	O
than	O
2000	O
Eumel	B-Operating_System
systems	O
shipped	O
,	O
mostly	O
to	O
schools	O
and	O
also	O
to	O
legal	O
practices	O
as	O
a	O
text	B-Device
processing	I-Device
platform	O
.	O
</s>
<s>
EUMEL	B-Operating_System
is	O
based	O
on	O
a	O
virtual	B-Architecture
machine	I-Architecture
using	O
a	O
bitcode	O
and	O
achieves	O
remarkable	O
performance	O
and	O
function	O
.	O
</s>
<s>
Z80-based	O
EUMEL	B-Operating_System
systems	O
provide	O
full	O
multi-user	O
multi-tasking	O
operation	O
with	O
virtual	O
memory	O
management	O
and	O
complete	O
isolation	O
of	O
one	O
process	O
against	O
all	O
others	O
.	O
</s>
<s>
These	O
systems	O
usually	O
execute	O
ELAN	B-Language
programs	O
faster	O
than	O
equivalent	O
programs	O
written	O
in	O
languages	O
such	O
as	O
COBOL	B-Application
,	O
BASIC	O
,	O
or	O
Pascal	B-Application
,	O
and	O
compiled	O
into	O
Z80	B-General_Concept
machine	B-Language
code	I-Language
on	O
other	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
One	O
of	O
the	O
main	O
features	O
of	O
EUMEL	B-Operating_System
is	O
that	O
it	O
is	O
persistent	B-Application
,	O
using	O
a	O
fixpoint/restart	O
logic	O
.	O
</s>
<s>
This	O
means	O
that	O
if	O
the	O
OS	O
crashes	B-General_Concept
,	O
or	O
the	O
power	O
fails	O
,	O
a	O
user	O
loses	O
only	O
a	O
few	O
minutes	O
of	O
work	O
:	O
on	O
restart	O
they	O
continue	O
working	O
from	O
the	O
prior	O
fixpoint	O
with	O
all	O
program	O
state	O
intact	O
fully	O
.	O
</s>
<s>
This	O
is	O
also	O
termed	O
orthogonal	O
persistence	B-Application
.	O
</s>
<s>
EUMEL	B-Operating_System
was	O
followed	O
by	O
the	O
L3	B-Operating_System
microkernel	B-Operating_System
,	O
and	O
later	O
the	O
L4	B-Operating_System
microkernel	I-Operating_System
family	I-Operating_System
.	O
</s>
