<s>
GEORGE	B-General_Concept
was	O
the	O
name	O
given	O
to	O
a	O
series	O
of	O
operating	B-General_Concept
systems	I-General_Concept
released	O
by	O
International	O
Computers	O
and	O
Tabulators	O
(	O
ICT	O
)	O
in	O
the	O
1960s	O
,	O
for	O
the	O
ICT	B-Device
1900	I-Device
series	I-Device
of	O
computers	O
.	O
</s>
<s>
These	O
included	O
GEORGE	B-General_Concept
1	I-General_Concept
,	O
GEORGE	B-General_Concept
2	I-General_Concept
,	O
GEORGE	B-General_Concept
3	I-General_Concept
,	O
and	O
GEORGE	B-General_Concept
4	I-General_Concept
.	O
</s>
<s>
Initially	O
the	O
1900	O
series	O
machines	O
,	O
like	O
the	O
Ferranti-Packard	B-Device
6000	I-Device
on	O
which	O
they	O
were	O
based	O
,	O
ran	O
a	O
simple	O
operating	B-General_Concept
system	I-General_Concept
known	O
as	O
Executive	B-Operating_System
which	O
allowed	O
the	O
system	O
operator	O
to	O
load	O
and	O
run	O
programs	O
from	O
a	O
Teletype	B-Application
Model	I-Application
33	I-Application
ASR	O
based	O
system	B-Device
console	I-Device
.	O
</s>
<s>
In	O
December	O
1964	O
ICT	O
set	O
up	O
an	O
Operating	B-General_Concept
Systems	I-General_Concept
Branch	O
to	O
develop	O
a	O
new	O
operating	B-General_Concept
system	I-General_Concept
for	O
the	O
1906/7	O
.	O
</s>
<s>
The	O
branch	O
was	O
initially	O
staffed	O
with	O
people	O
being	O
released	O
by	O
the	O
end	O
of	O
work	O
on	O
the	O
OMP	O
operating	B-General_Concept
system	I-General_Concept
for	O
the	O
Ferranti	B-Device
Orion	I-Device
.	O
</s>
<s>
The	O
initial	O
design	O
of	O
the	O
new	O
system	O
,	O
named	O
George	B-General_Concept
after	O
George	B-General_Concept
E	O
.	O
Felton	O
head	O
of	O
the	O
Basic	O
Programming	O
Division	O
,	O
was	O
based	O
on	O
ideas	O
from	O
the	O
Orion	O
and	O
the	O
spooling	B-Device
system	O
of	O
the	O
Atlas	B-Device
computer	I-Device
.	O
</s>
<s>
(	O
In	O
public	O
it	O
was	O
claimed	O
that	O
George	B-General_Concept
stood	O
for	O
GEneral	O
ORGanisational	O
Environment	O
,	O
but	O
contemporary	O
sources	O
say	O
that	O
was	O
a	O
backronym	O
)	O
.	O
</s>
<s>
In	O
July	O
1965	O
a	O
team	O
from	O
ICT	O
was	O
present	O
at	O
a	O
seminar	O
at	O
NPL	O
describing	O
the	O
CTSS	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
developed	O
for	O
MIT	O
's	O
Project	O
MAC	O
.	O
</s>
<s>
They	O
decided	O
that	O
the	O
ICT	O
would	O
need	O
to	O
provide	O
multi-access	B-General_Concept
facilities	O
,	O
known	O
to	O
ICT	O
as	O
MOP	O
,	O
"	O
Multiple	O
Online	O
Processing	O
"	O
.	O
</s>
<s>
In	O
November	O
1965	O
H	O
.	O
P	O
.	O
Goodman	O
,	O
head	O
of	O
the	O
Operating	B-General_Concept
Systems	I-General_Concept
Branch	O
attended	O
the	O
Fall	O
Joint	O
Computer	O
Conference	O
in	O
Las	O
Vegas	O
where	O
plans	O
for	O
Multics	B-Application
were	O
initially	O
described	O
.	O
</s>
<s>
Some	O
of	O
the	O
Multics	B-Application
features	O
discussed	O
influenced	O
future	O
development	O
of	O
George	B-General_Concept
,	O
notably	O
the	O
tree	O
structured	O
filestore	O
.	O
</s>
<s>
Towards	O
the	O
end	O
of	O
1965	O
ICT	O
marketing	O
requested	O
that	O
a	O
simpler	O
operating	B-General_Concept
system	I-General_Concept
be	O
made	O
available	O
quickly	O
,	O
especially	O
for	O
the	O
smaller	O
members	O
of	O
the	O
range	O
.	O
</s>
<s>
It	O
was	O
decided	O
that	O
two	O
smaller	O
systems	O
,	O
known	O
as	O
George	B-General_Concept
1	I-General_Concept
and	O
George	B-General_Concept
2	I-General_Concept
be	O
released	O
rapidly	O
,	O
and	O
the	O
larger	O
operating	B-General_Concept
system	I-General_Concept
was	O
renamed	O
George	B-General_Concept
3	I-General_Concept
.	O
</s>
<s>
George	B-General_Concept
1	I-General_Concept
was	O
a	O
simple	O
batch	B-General_Concept
processing	I-General_Concept
system	O
,	O
Job	O
descriptions	O
were	O
read	O
from	O
cards	O
or	O
paper	O
tape	O
which	O
controlled	O
the	O
loading	O
and	O
running	O
of	O
programs	O
,	O
either	O
loaded	O
from	O
cards	O
or	O
paper	O
tape	O
or	O
magnetic	O
tape	O
.	O
</s>
<s>
The	O
job	B-Application
control	I-Application
language	I-Application
allowed	O
definition	O
of	O
the	O
peripherals	O
and	O
files	O
to	O
be	O
used	O
and	O
handling	O
of	O
exception	O
conditions	O
.	O
</s>
<s>
George	B-General_Concept
used	O
the	O
trusted	O
program	O
facilities	O
provided	O
by	O
executive	B-Operating_System
to	O
run	O
the	O
user	O
programs	O
.	O
</s>
<s>
George	B-General_Concept
2	I-General_Concept
added	O
the	O
concept	O
of	O
off	O
line	O
peripheral	O
handling	O
(	O
spooling	B-Device
)	O
.	O
</s>
<s>
A	O
module	O
was	O
also	O
available	O
for	O
entering	O
jobs	O
from	O
remote	B-Protocol
job	I-Protocol
entry	I-Protocol
stations	O
,	O
the	O
output	O
of	O
the	O
job	O
could	O
be	O
printed	O
on	O
the	O
remote	O
printer	O
.	O
</s>
<s>
The	O
George	B-General_Concept
2	I-General_Concept
job	B-Application
control	I-Application
language	I-Application
allowed	O
use	O
of	O
stored	O
macros	O
with	O
conditional	O
facilities	O
.	O
</s>
<s>
George	B-General_Concept
2	I-General_Concept
provided	O
no	O
file	O
system	O
,	O
the	O
system	O
and	O
user	O
programs	O
relied	O
on	O
the	O
facilities	O
provided	O
by	O
executive	B-Operating_System
.	O
</s>
<s>
MINIMOP	B-Operating_System
could	O
be	O
run	O
simultaneously	O
with	O
GEORGE	B-General_Concept
2	I-General_Concept
on	O
the	O
same	O
machine	O
,	O
to	O
provide	O
on-line	O
time-sharing	B-General_Concept
facilities	O
.	O
</s>
<s>
GEORGE	B-General_Concept
3	I-General_Concept
was	O
the	O
main	O
version	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
series	O
for	O
the	O
larger	O
machines	O
of	O
the	O
1900	O
series	O
.	O
</s>
<s>
In	O
contrast	O
to	O
George	B-General_Concept
1	I-General_Concept
&	O
2	O
which	O
ran	O
as	O
user-mode	O
programs	O
under	O
executive	B-Operating_System
,	O
George	B-General_Concept
3	I-General_Concept
was	O
a	O
full	O
operating	B-General_Concept
system	I-General_Concept
,	O
leaving	O
only	O
low-level	O
peripheral	O
and	O
interrupt	O
handling	O
to	O
a	O
cut-down	O
version	O
of	O
executive	B-Operating_System
.	O
</s>
<s>
George	B-General_Concept
3	I-General_Concept
was	O
implemented	O
as	O
a	O
small	O
memory-resident	O
part	O
and	O
a	O
collection	O
of	O
chapters	O
(	O
overlays	B-General_Concept
)	O
which	O
were	O
loaded	O
into	O
and	O
removed	O
from	O
memory	O
as	O
needed	O
.	O
</s>
<s>
Internally	O
George	B-General_Concept
used	O
cooperative	B-Operating_System
multitasking	I-Operating_System
;	O
context	B-Operating_System
switches	I-Operating_System
could	O
take	O
place	O
at	O
any	O
chapter	O
change	O
(	O
call	O
from	O
one	O
chapter	O
to	O
another	O
)	O
,	O
or	O
at	O
other	O
specified	O
places	O
in	O
the	O
code	O
.	O
</s>
<s>
User-level	O
code	O
was	O
run	O
using	O
preemptive	O
multitasking	O
;	O
context	B-Operating_System
switches	I-Operating_System
were	O
forced	O
on	O
I/O	O
operations	O
or	O
clock	O
ticks	O
.	O
</s>
<s>
George	B-General_Concept
was	O
written	O
in	O
a	O
special	O
assembler	B-Language
,	O
GIN	O
(	O
George	B-General_Concept
INput	O
)	O
,	O
which	O
had	O
richer	O
conditional	B-Application
compilation	I-Application
and	O
macro	O
facilities	O
than	O
the	O
standard	O
PLAN	O
assembler	B-Language
.	O
</s>
<s>
Macros	O
were	O
heavily	O
used	O
by	O
the	O
code	O
to	O
reduce	O
the	O
effort	O
of	O
programming	O
such	O
a	O
large	O
system	O
in	O
assembly	B-Language
language	I-Language
.	O
</s>
<s>
In	O
later	O
versions	O
the	O
macro	O
features	O
of	O
GIN	O
were	O
used	O
to	O
add	O
structured	B-Language
programming	I-Language
features	O
to	O
the	O
code	O
.	O
</s>
<s>
George	B-General_Concept
3	I-General_Concept
was	O
a	O
mixed	O
batch	O
and	O
online	O
system	O
.	O
</s>
<s>
Jobs	O
could	O
be	O
run	O
from	O
cards	O
or	O
tape	O
in	O
the	O
same	O
manner	O
as	O
George	B-General_Concept
2	I-General_Concept
,	O
or	O
interactively	O
from	O
MOP	O
(	O
Multiple	O
Online	O
Processing	O
)	O
terminals	O
,	O
either	O
simple	O
Teletype	B-Application
Model	I-Application
33	I-Application
ASR	O
terminals	O
or	O
block	O
mode	O
VDU	O
terminals	O
.	O
</s>
<s>
The	O
job	B-Application
control	I-Application
language	I-Application
was	O
the	O
same	O
on	O
terminals	O
or	O
in	O
batch	B-General_Concept
jobs	I-General_Concept
and	O
included	O
conditional	O
operations	O
and	O
macro	O
operations	O
.	O
</s>
<s>
In	O
contrast	O
to	O
Unix	B-Application
systems	I-Application
the	O
job	B-Application
control	I-Application
language	I-Application
was	O
part	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
rather	O
than	O
being	O
a	O
user	O
level	O
shell	B-Operating_System
process	O
.	O
</s>
<s>
George	B-General_Concept
3	I-General_Concept
provided	O
a	O
tree	O
structured	O
Filestore	O
,	O
inspired	O
in	O
part	O
by	O
Multics	B-Application
.	O
</s>
<s>
The	O
underlying	O
disc	O
storage	O
mechanism	O
George	B-General_Concept
3	I-General_Concept
,	O
in	O
1968	O
,	O
was	O
probably	O
the	O
earliest	O
commercial	O
version	O
of	O
a	O
Copy-On-Write	B-Language
file	O
system	O
.	O
</s>
<s>
This	O
allowed	O
older	O
George	B-General_Concept
1	I-General_Concept
&	O
2	O
programs	O
that	O
required	O
these	O
physical	O
devices	O
,	O
to	O
be	O
run	O
under	O
George	B-General_Concept
3	I-General_Concept
without	O
modification	O
.	O
</s>
<s>
This	O
could	O
speed	O
up	O
jobs	O
that	O
required	O
many	O
tape	O
or	O
disc	O
changes	O
on	O
George	B-General_Concept
1	I-General_Concept
&	O
2	O
to	O
be	O
automated	O
to	O
the	O
extent	O
that	O
something	O
that	O
had	O
required	O
two	O
operators	O
,	O
several	O
tens	O
of	O
tape	O
changes	O
and	O
five	O
hours	O
,	O
now	O
required	O
no	O
operators	O
,	O
other	O
than	O
for	O
mounting	O
two	O
work	O
tapes	O
for	O
the	O
results	O
,	O
and	O
finished	O
in	O
45	O
minutes	O
.	O
</s>
<s>
Starting	O
with	O
the	O
1904A	O
,	O
a	O
paging	B-Architecture
unit	O
was	O
available	O
for	O
larger	O
1900	O
processors	O
and	O
George	B-General_Concept
4	I-General_Concept
was	O
written	O
to	O
take	O
advantage	O
of	O
it	O
.	O
</s>
<s>
George	B-General_Concept
4	I-General_Concept
remained	O
compatible	O
with	O
George	B-General_Concept
3	I-General_Concept
.	O
</s>
<s>
It	O
was	O
common	O
to	O
alternate	O
George	B-General_Concept
3	I-General_Concept
and	O
4	O
on	O
the	O
same	O
machine	O
and	O
filestore	O
,	O
running	O
George	B-General_Concept
3	I-General_Concept
during	O
the	O
day	O
for	O
small	O
,	O
interactive	O
workloads	O
and	O
George	B-General_Concept
4	I-General_Concept
at	O
night	O
for	O
large	O
,	O
memory	O
intensive	O
,	O
jobs	O
.	O
</s>
<s>
George	B-General_Concept
4	I-General_Concept
introduced	O
the	O
concept	O
of	O
a	O
sparse	O
program	O
,	O
a	O
program	O
that	O
had	O
an	O
addressing	O
space	O
larger	O
than	O
its	O
allocated	O
memory	O
and	O
read-only	O
(	O
pure	O
)	O
data	O
and	O
code	O
regions	O
.	O
</s>
<s>
The	O
source	O
code	O
of	O
George	B-General_Concept
3	I-General_Concept
and	O
4	O
were	O
the	O
same	O
;	O
conditional	B-Application
compilation	I-Application
facilities	O
of	O
the	O
GIN	O
assembler	B-Language
were	O
used	O
to	O
select	O
which	O
version	O
of	O
the	O
system	O
was	O
being	O
compiled	O
.	O
</s>
<s>
As	O
the	O
1900	O
paging	B-Architecture
feature	O
was	O
not	O
emulated	O
by	O
the	O
2900	B-Device
series	I-Device
machines	O
used	O
by	O
later	O
George	B-General_Concept
installations	O
,	O
George	B-General_Concept
4	I-General_Concept
fell	O
out	O
of	O
use	O
before	O
George	B-General_Concept
3	I-General_Concept
.	O
</s>
<s>
George	B-General_Concept
was	O
distributed	O
in	O
a	O
form	O
that	O
allowed	O
a	O
site	O
to	O
modify	O
large	O
parts	O
of	O
the	O
system	O
.	O
</s>
<s>
Versions	O
of	O
George	B-General_Concept
3	I-General_Concept
before	O
release	O
8	O
were	O
provided	O
in	O
binary	O
form	O
.	O
</s>
<s>
To	O
simplify	O
the	O
process	O
most	O
George	B-General_Concept
chapters	O
included	O
an	O
empty	O
MEND	O
area	O
at	O
the	O
end	O
.	O
</s>
<s>
Starting	O
with	O
release	O
8	O
the	O
source	O
of	O
George	B-General_Concept
was	O
distributed	O
with	O
the	O
binary	O
,	O
both	O
on	O
magnetic	O
tape	O
and	O
microfiche	O
.	O
</s>
<s>
The	O
George	B-General_Concept
user	O
group	O
set	O
up	O
a	O
"	O
MEND	O
exchange	O
scheme	O
"	O
to	O
share	O
interesting	O
modifications	O
to	O
George	B-General_Concept
.	O
</s>
<s>
When	O
ICL	O
produced	O
a	O
new	O
version	O
of	O
George	B-General_Concept
they	O
would	O
sometimes	O
include	O
modifications	O
produced	O
by	O
the	O
users	O
.	O
</s>
<s>
For	O
the	O
last	O
released	O
version	O
,	O
8.67	O
,	O
most	O
of	O
the	O
patches	O
from	O
the	O
MEND	O
exchange	O
scheme	O
were	O
included	O
in	O
the	O
standard	O
George	B-General_Concept
source	O
,	O
switched	O
off	O
by	O
conditional	B-Application
compilation	I-Application
.	O
</s>
<s>
They	O
can	O
be	O
turned	O
on	O
as	O
part	O
of	O
the	O
standard	O
process	O
of	O
tailoring	O
George	B-General_Concept
for	O
a	O
site	O
.	O
</s>
<s>
GEOrge	B-General_Concept
was	O
well	O
documented	O
internally	O
in	O
a	O
series	O
of	O
looseleaf	O
folders	O
,	O
distributed	O
as	O
an	O
initial	O
version	O
plus	O
amendments	O
.	O
</s>
<s>
A	O
modified	O
version	O
of	O
George	B-General_Concept
3	I-General_Concept
was	O
supplied	O
to	O
the	O
University	O
of	O
Manchester	O
Regional	O
Computer	O
Centre	O
(	O
UMRCC	O
)	O
.	O
</s>
<s>
This	O
linked	O
George	B-General_Concept
3	I-General_Concept
to	O
a	O
CDC	B-Device
Cyber	I-Device
machine	O
,	O
to	O
which	O
George	B-General_Concept
supplied	O
the	O
offline	O
I/O	O
and	O
Job	O
queueing	O
functions	O
.	O
</s>
<s>
With	O
the	O
release	O
of	O
ICL	O
's	O
"	O
new	O
range	O
"	O
,	O
the	O
2900	B-Device
series	I-Device
with	O
its	O
VME	B-General_Concept
operating	B-General_Concept
system	I-General_Concept
,	O
George	B-General_Concept
became	O
obsolete	O
.	O
</s>
<s>
However	O
,	O
due	O
to	O
the	O
legacy	O
of	O
investment	O
in	O
software	O
for	O
George	B-General_Concept
,	O
ICL	O
released	O
options	O
to	O
run	O
1900	O
series	O
software	O
,	O
including	O
George	B-General_Concept
,	O
on	O
2900	B-Device
series	I-Device
machines	O
,	O
initially	O
the	O
Direct	B-Operating_System
Machine	I-Operating_System
Environment	I-Operating_System
(	O
DME	O
)	O
,	O
later	O
the	O
Concurrent	O
Machine	O
Environment	O
(	O
CME	O
)	O
which	O
allowed	O
simultaneous	O
running	O
of	O
1900	O
and	O
2900	O
code	O
on	O
the	O
same	O
system	O
.	O
</s>
<s>
New	O
versions	O
of	O
George	B-General_Concept
3	I-General_Concept
continued	O
to	O
be	O
released	O
for	O
the	O
2900	O
.	O
</s>
<s>
As	O
of	O
2005	O
at	O
least	O
one	O
site	O
in	O
Russia	O
was	O
still	O
running	O
George	B-General_Concept
3	I-General_Concept
under	O
DME	O
.	O
</s>
<s>
In	O
November	O
2014	O
George	B-General_Concept
3	I-General_Concept
was	O
run	O
on	O
a	O
reconditioned	O
ICL	B-Device
2966	I-Device
at	O
the	O
National	O
Museum	O
of	O
Computing	O
.	O
</s>
<s>
David	O
Holdsworth	O
and	O
Delwyn	O
Holroyd	O
obtained	O
copies	O
of	O
George	B-General_Concept
3	I-General_Concept
issue	O
tapes	O
when	O
the	O
last	O
live	O
site	O
in	O
the	O
UK	O
,	O
at	O
British	O
Steel	O
Corporation	O
,	O
was	O
being	O
decommissioned	O
and	O
wrote	O
an	O
emulator	O
for	O
the	O
1900	O
hardware	O
and	O
executive	B-Operating_System
that	O
allows	O
running	O
of	O
George	B-General_Concept
on	O
Microsoft	B-Application
Windows	I-Application
and	O
Linux	B-Application
as	O
part	O
of	O
a	O
project	O
for	O
the	O
Computer	O
Conservation	O
Society	O
.	O
</s>
