<s>
MINIMOP	B-Operating_System
was	O
an	O
operating	B-General_Concept
system	I-General_Concept
which	O
ran	O
on	O
the	O
International	O
Computers	O
Limited	O
(	O
ICL	O
)	O
1900	B-Device
series	I-Device
of	O
computers	O
.	O
</s>
<s>
MINIMOP	B-Operating_System
provided	O
an	O
on-line	O
,	O
time-sharing	B-General_Concept
environment	O
(	O
Multiple	O
Online	O
Programming	O
,	O
or	O
MOP	O
in	O
ICL	O
terminology	O
)	O
,	O
and	O
typically	O
ran	O
alongside	O
George	B-General_Concept
2	I-General_Concept
running	O
batch	B-General_Concept
jobs	I-General_Concept
.	O
</s>
<s>
MINIMOP	B-Operating_System
was	O
named	O
to	O
reflect	O
its	O
role	O
as	O
an	O
alternative	O
to	O
the	O
MOP	O
facilities	O
of	O
George	B-General_Concept
3	I-General_Concept
,	O
which	O
required	O
a	O
more	O
powerful	O
machine	O
.	O
</s>
<s>
MINIMOP	B-Operating_System
would	O
run	O
on	O
all	O
1900	O
processors	O
apart	O
from	O
the	O
low-end	O
1901	O
and	O
1902	O
and	O
required	O
only	O
16K	O
words	O
of	O
memory	O
and	O
two	O
4	O
or	O
8	O
million	O
character	O
magnetic	O
disks	O
.	O
</s>
<s>
MINIMOP	B-Operating_System
was	O
implemented	O
as	O
a	O
multithreaded	B-General_Concept
(	O
sub-programmed	O
in	O
ICL	O
terminology	O
)	O
user	O
level	O
program	O
running	O
on	O
the	O
standard	O
executive	O
(	O
low	O
level	O
operating	B-General_Concept
system	I-General_Concept
)	O
of	O
the	O
ICL	B-Device
1900	I-Device
.	O
</s>
<s>
The	O
program	O
under	O
control	O
facilities	O
of	O
executive	O
were	O
used	O
to	O
run	O
user	O
programs	O
under	O
MINIMOP	B-Operating_System
.	O
</s>
<s>
All	O
user	O
I/O	O
operations	O
were	O
trapped	O
by	O
MINIMOP	B-Operating_System
and	O
emulated	O
rather	O
than	O
accessing	O
real	O
peripherals	O
.	O
</s>
<s>
Queen	O
Mary	O
College	O
,	O
London	O
,	O
now	O
Queen	O
Mary	O
,	O
University	O
of	O
London	O
,	O
later	O
developed	O
MAXIMOP	O
,	O
an	O
improved	O
system	O
largely	O
compatible	O
with	O
MINIMOP	B-Operating_System
.	O
</s>
