<s>
The	O
Ferranti	B-Device
Mark	I-Device
1	I-Device
,	O
also	O
known	O
as	O
the	O
Manchester	B-Device
Electronic	I-Device
Computer	I-Device
in	O
its	O
sales	O
literature	O
,	O
and	O
thus	O
sometimes	O
called	O
the	O
Manchester	B-Device
Ferranti	I-Device
,	O
was	O
produced	O
by	O
British	O
electrical	O
engineering	O
firm	O
Ferranti	O
Ltd	O
.	O
</s>
<s>
It	O
was	O
"	O
the	O
tidied	O
up	O
and	O
commercialised	O
version	O
of	O
the	O
Manchester	B-Device
Mark	I-Device
I	I-Device
"	O
.	O
</s>
<s>
The	O
first	O
machine	O
was	O
delivered	O
to	O
the	O
Victoria	O
University	O
of	O
Manchester	O
in	O
September	O
1949	O
(	O
publicly	O
demonstrated	O
in	O
July	O
)	O
ahead	O
of	O
the	B-Operating_System
UNIVAC	I-Operating_System
I	O
,	O
which	O
was	O
sold	O
to	O
the	O
United	O
States	O
Census	O
Bureau	O
on	O
31	O
March	O
1951	O
,	O
although	O
not	O
delivered	O
until	O
late	O
December	O
the	O
following	O
year	O
.	O
</s>
<s>
Based	O
on	O
the	O
Manchester	B-Device
Mark	I-Device
1	I-Device
,	O
which	O
was	O
designed	O
at	O
the	O
University	O
of	O
Manchester	O
by	O
Freddie	O
Williams	O
and	O
Tom	O
Kilburn	O
,	O
the	O
machine	O
was	O
built	O
by	O
Ferranti	O
of	O
the	O
United	O
Kingdom	O
.	O
</s>
<s>
The	O
Mark	O
1	O
used	O
a	O
20-bit	O
word	O
stored	O
as	O
a	O
single	O
line	O
of	O
dots	O
of	O
electric	O
charges	O
settled	O
on	O
the	O
surface	O
of	O
a	O
Williams	B-General_Concept
tube	I-General_Concept
display	O
,	O
each	O
cathodic	O
tube	O
storing	O
64lines	O
of	O
dots	O
.	O
</s>
<s>
Other	O
tubes	O
stored	O
the	O
single	O
80-bit	O
accumulator	B-General_Concept
(	O
A	O
)	O
,	O
the	O
40-bit	O
"	O
multiplicand/quotient	O
register	O
"	O
(	O
MQ	O
)	O
and	O
eight	O
"	O
B-lines	O
"	O
,	O
or	O
index	B-General_Concept
registers	I-General_Concept
,	O
which	O
was	O
one	O
of	O
the	O
unique	O
features	O
of	O
the	O
Mark	O
1	O
design	O
.	O
</s>
<s>
The	O
accumulator	B-General_Concept
could	O
also	O
be	O
addressed	O
as	O
two	O
40-bit	O
words	O
.	O
</s>
<s>
Secondary	O
storage	O
was	O
provided	O
in	O
the	O
form	O
of	O
a	O
512-page	O
magnetic	B-General_Concept
drum	I-General_Concept
,	O
storing	O
two	O
pages	O
per	O
track	O
,	O
with	O
about	O
30	O
milliseconds	O
revolution	O
time	O
.	O
</s>
<s>
The	O
instructions	O
,	O
like	O
the	O
Manchester	O
machine	O
,	O
used	O
a	O
single	O
address	O
format	O
in	O
which	O
operands	O
were	O
modified	O
and	O
left	O
in	O
the	O
accumulator	B-General_Concept
.	O
</s>
<s>
Several	O
instructions	O
were	O
included	O
to	O
copy	O
a	O
word	O
of	O
memory	O
from	O
one	O
of	O
the	O
Williams	B-General_Concept
tubes	I-General_Concept
to	O
a	O
paper	O
tape	O
machine	O
,	O
or	O
read	O
them	O
back	O
in	O
.	O
</s>
<s>
After	O
the	O
first	O
two	O
machines	O
,	O
a	O
revised	O
version	O
of	O
the	O
design	O
became	O
available	O
,	O
known	O
as	O
the	O
Ferranti	B-Device
Mark	I-Device
1	I-Device
Star	O
or	O
the	O
Ferranti	O
Mark	O
1*	O
.	O
</s>
<s>
The	O
revisions	O
mainly	O
cleaned	O
up	O
the	O
instruction	B-General_Concept
set	I-General_Concept
for	O
better	O
usability	O
.	O
</s>
<s>
Additionally	O
,	O
several	O
commands	O
that	O
used	O
the	O
index	B-General_Concept
registers	I-General_Concept
had	O
side	O
effects	O
that	O
led	O
to	O
quirky	O
programming	O
,	O
but	O
these	O
were	O
modified	O
to	O
have	O
no	O
side	O
effects	O
.	O
</s>
<s>
Another	O
was	O
installed	O
at	O
Avro	B-Operating_System
,	O
the	O
aircraft	O
manufacturers	O
,	O
at	O
their	O
Chadderton	O
factory	O
in	O
Manchester	O
.	O
</s>
<s>
Included	O
in	O
the	O
Ferranti	B-Device
Mark	I-Device
1	I-Device
's	O
instruction	B-General_Concept
set	I-General_Concept
was	O
a	O
hoot	O
command	O
,	O
which	O
enabled	O
the	O
machine	O
to	O
give	O
auditory	O
feedback	O
to	O
its	O
operators	O
.	O
</s>
<s>
It	O
was	O
not	O
,	O
however	O
,	O
the	O
first	B-Architecture
computer	I-Architecture
to	O
have	O
played	O
music	O
;	O
CSIRAC	B-Device
,	O
Australia	O
's	O
first	O
digital	O
computer	O
,	O
achieved	O
that	O
with	O
a	O
rendition	O
of	O
"	O
Colonel	O
Bogey	O
"	O
.	O
</s>
<s>
In	O
November	O
1951	O
,	O
Dr.	O
Dietrich	O
Prinz	O
wrote	O
one	O
of	O
the	O
earliest	B-Architecture
computer	I-Architecture
games	O
,	O
a	O
chess-playing	O
program	O
for	O
the	O
Manchester	B-Device
Ferranti	I-Device
Mark	O
1	O
computer	O
.	O
</s>
<s>
The	O
program	O
's	O
restrictions	O
were	O
:	O
no	O
castling	O
,	O
no	O
double	O
pawn	O
move	O
,	O
no	O
en	O
passant	O
capture	O
,	O
no	O
pawn	O
promotion	O
,	O
and	O
no	O
distinction	O
between	O
checkmate	B-Application
and	O
stalemate	O
.	O
</s>
