<s>
The	O
FP-6000	O
was	O
a	O
second-generation	O
mainframe	B-Architecture
computer	I-Architecture
developed	O
and	O
built	O
by	O
Ferranti-Packard	O
,	O
the	O
Canadian	O
division	O
of	O
Ferranti	O
,	O
in	O
the	O
early	O
1960s	O
.	O
</s>
<s>
It	O
is	O
particularly	O
notable	O
for	O
supporting	O
multitasking	B-Operating_System
,	O
being	O
one	O
of	O
the	O
first	O
commercial	O
machines	O
to	O
do	O
so	O
.	O
</s>
<s>
Only	O
six	O
FP-6000s	O
were	O
sold	O
before	O
the	O
computer	O
division	O
of	O
Ferranti-Packard	O
was	O
sold	O
off	O
by	O
Ferranti	O
's	O
UK	O
headquarters	O
in	O
1963	O
,	O
the	O
FP-6000	O
becoming	O
the	O
basis	O
for	O
the	O
mid-range	O
machines	O
of	O
the	O
ICT	B-Device
1900	I-Device
,	O
which	O
sold	O
into	O
the	O
thousands	O
in	O
Europe	O
.	O
</s>
<s>
What	O
was	O
to	O
become	O
the	O
FP-6000	O
had	O
its	O
genesis	O
in	O
a	O
Royal	O
Canadian	O
Navy	O
project	O
starting	O
in	O
1949	O
called	O
DATAR	B-Device
.	O
</s>
<s>
For	O
DATAR	B-Device
,	O
Ferranti-Packard	O
(	O
then	O
still	O
known	O
as	O
Ferranti	O
Canada	O
)	O
built	O
an	O
experimental	O
computer	O
to	O
share	O
information	O
among	O
ships	O
in	O
a	O
convoy	O
.	O
</s>
<s>
Although	O
the	O
prototype	O
was	O
a	O
success	O
,	O
the	O
failure	O
rate	O
of	O
the	O
vacuum	O
tubes	O
was	O
a	O
concern	O
to	O
everyone	O
and	O
Ferranti	O
suggested	O
they	O
re-build	O
the	O
machine	O
using	O
transistors	B-Application
instead	O
.	O
</s>
<s>
DATAR	B-Device
ran	O
out	O
of	O
funds	O
before	O
this	O
conversion	O
could	O
take	O
place	O
,	O
but	O
Ferranti	O
put	O
the	O
experience	O
to	O
good	O
use	O
in	O
a	O
series	O
of	O
one-off	O
transistorized	B-Device
machines	I-Device
.	O
</s>
<s>
The	O
developmental	O
series	O
eventually	O
culminated	O
in	O
ReserVec	B-Device
.	O
</s>
<s>
ReserVec	B-Device
was	O
the	O
first	O
computerized	B-Application
reservation	I-Application
system	I-Application
to	O
enter	O
service	O
when	O
it	O
took	O
over	O
all	O
bookings	O
for	O
Air	O
Canada	O
in	O
1961	O
.	O
</s>
<s>
Their	O
project	O
was	O
never	O
delivered	O
,	O
and	O
ReserVec	B-Device
withered	O
.	O
</s>
<s>
Ferranti-Packard	O
was	O
unwilling	O
to	O
simply	O
let	O
the	O
development	O
effort	O
go	O
to	O
waste	O
,	O
and	O
started	O
looking	O
for	O
ways	O
to	O
commercialize	O
the	O
ReserVec	B-Device
hardware	O
into	O
a	O
general	O
purpose	O
mainframe	B-Architecture
.	O
</s>
<s>
These	O
were	O
a	O
1950s	O
replacement	O
for	O
transistors	B-Application
;	O
at	O
that	O
time	O
transistors	B-Application
were	O
extremely	O
expensive	O
and	O
still	O
had	O
reliability	O
issues	O
.	O
</s>
<s>
Magnetic	O
amplifiers	O
were	O
larger	O
than	O
transistors	B-Application
but	O
had	O
the	O
advantage	O
of	O
allowing	O
a	O
single	O
amplifier	O
to	O
be	O
shared	O
among	O
several	O
circuits	O
,	O
lowering	O
component	O
counts	O
.	O
</s>
<s>
When	O
newer	O
transistors	B-Application
were	O
introduced	O
at	O
lower	O
price	O
points	O
,	O
interest	O
in	O
magnetic	O
amplifiers	O
disappeared	O
almost	O
overnight	O
.	O
</s>
<s>
Ken	O
Johnson	O
,	O
an	O
engineer	O
at	O
Ferranti	O
's	O
computer	O
division	O
in	O
Manchester	O
,	O
noticed	O
that	O
it	O
would	O
be	O
possible	O
to	O
wire	O
these	O
new	O
transistors	B-Application
in	O
the	O
same	O
way	O
as	O
the	O
magnetic	O
amplifiers	O
,	O
thereby	O
reusing	O
a	O
single	O
transistor	B-Application
for	O
several	O
tasks	O
,	O
and	O
in	O
turn	O
,	O
greatly	O
lowering	O
component	O
costs	O
.	O
</s>
<s>
In	O
1960	O
,	O
the	O
smaller	O
design	O
was	O
delivered	O
as	O
the	O
Ferranti	B-Device
Sirius	I-Device
,	O
a	O
desk-sized	O
system	O
for	O
small	O
businesses	O
.	O
</s>
<s>
The	O
larger	O
machine	O
,	O
the	O
Ferranti	B-Device
Orion	I-Device
,	O
was	O
developed	O
in	O
parallel	O
and	O
formally	O
announced	O
in	O
1960	O
with	O
the	O
first	O
unit	O
shipping	O
in	O
1961	O
.	O
</s>
<s>
While	O
this	O
was	O
taking	O
place	O
,	O
a	O
separate	O
group	O
within	O
Ferranti	O
was	O
formed	O
to	O
consider	O
a	O
replacement	O
for	O
the	O
successful	O
tube-based	O
Ferranti	B-Device
Pegasus	I-Device
.	O
</s>
<s>
Harriac	O
was	O
essentially	O
a	O
transistorized	O
Pegasus	B-Device
with	O
more	O
modern	O
features	O
,	O
and	O
as	O
such	O
,	O
it	O
would	O
have	O
fit	O
into	O
Ferranti	O
's	O
product	O
line	O
at	O
about	O
the	O
same	O
level	O
as	O
the	O
Orion	O
.	O
</s>
<s>
They	O
decided	O
to	O
combine	O
the	O
Harriac	O
specification	O
with	O
their	O
own	O
successful	O
transistorized	O
circuitry	O
developed	O
for	O
ReserVec	B-Device
.	O
</s>
<s>
To	O
provide	O
the	O
illusion	O
of	O
being	O
at	O
zero	O
,	O
in	O
a	O
multiprogramming	O
machine	O
each	O
program	O
was	O
assigned	O
a	O
fixed	O
amount	O
of	O
the	O
core	B-General_Concept
memory	I-General_Concept
,	O
its	O
base	O
location	O
is	O
known	O
as	O
the	O
datum	O
and	O
the	O
last	O
location	O
as	O
the	O
limit	O
.	O
</s>
<s>
In	O
order	O
to	O
prevent	O
fragmentation	O
of	O
memory	O
,	O
every	O
time	O
a	O
program	O
terminated	O
,	O
the	O
FP-6000	O
'	O
s	O
operating	B-General_Concept
system	I-General_Concept
,	O
known	O
as	O
Executive	O
,	O
would	O
temporarily	O
stop	O
the	O
other	O
programs	O
and	O
recopy	O
them	O
to	O
the	O
lowest	O
available	O
location	O
in	O
core	O
.	O
</s>
<s>
This	O
would	O
make	O
the	O
system	O
unsuitable	O
for	O
running	O
an	O
operating	B-General_Concept
system	I-General_Concept
such	O
as	O
Unix	B-Application
,	O
which	O
is	O
made	O
up	O
of	O
a	O
series	O
of	O
tiny	O
programs	O
that	O
are	O
frequently	O
started	O
and	O
stopped	O
,	O
but	O
Unix	B-Application
did	O
not	O
exist	O
at	O
the	O
time	O
,	O
and	O
the	O
model	O
for	O
most	O
operating	B-General_Concept
systems	I-General_Concept
was	O
a	O
sort	O
of	O
"	O
extended	O
batch	O
mode	O
"	O
,	O
running	O
long-lived	O
programs	O
that	O
paused	O
when	O
not	O
being	O
actively	O
fed	O
data	O
.	O
</s>
<s>
The	O
system	O
included	O
64	O
hardware	O
channels	O
that	O
could	O
be	O
connected	O
to	O
peripherals	O
of	O
any	O
sort	O
and	O
could	O
be	O
supplied	O
with	O
a	O
wide	O
variety	O
of	O
core	B-General_Concept
memory	I-General_Concept
sizes	O
.	O
</s>
<s>
In	O
other	O
ways	O
the	O
machine	O
was	O
fairly	O
similar	O
to	O
the	O
ReserVec	B-Device
's	O
Gemini	O
machine	O
,	O
using	O
a	O
24-bit	O
word	O
with	O
a	O
25th-bit	O
for	O
parity	B-Error_Name
checking	I-Error_Name
and	O
a	O
simple	O
machine	B-Language
language	I-Language
.	O
</s>
<s>
One	O
change	O
was	O
the	O
lack	O
of	O
a	O
memory	B-General_Concept
drum	I-General_Concept
,	O
as	O
the	O
advances	O
in	O
core	O
allowed	O
them	O
to	O
replace	O
the	O
drum	O
entirely	O
.	O
</s>
<s>
The	O
FP-6000	O
,	O
with	O
the	O
addition	O
of	O
the	O
ICT	O
Standard	O
Interface	O
,	O
became	O
the	O
ICT	B-Device
1904	I-Device
,	O
and	O
a	O
slightly	O
modified	O
version	O
would	O
be	O
offered	O
as	O
the	O
ICT	B-Device
1905	I-Device
.	O
</s>
