<s>
CSIRAC	B-Device
(	O
;	O
Commonwealth	O
Scientific	O
and	O
Industrial	O
Research	O
Automatic	O
Computer	O
)	O
,	O
originally	O
known	O
as	O
CSIR	B-Device
Mk	I-Device
1	I-Device
,	O
was	O
Australia	O
's	O
first	O
digital	O
computer	O
,	O
and	O
the	O
fifth	O
stored	O
program	O
computer	O
in	O
the	O
world	O
.	O
</s>
<s>
(	O
the	O
Zuse	B-Device
Z4	I-Device
at	O
the	O
Deutsches	O
Museum	O
is	O
older	O
,	O
but	O
was	O
electro-mechanical	O
,	O
not	O
electronic	B-Architecture
)	O
,	O
and	O
was	O
the	O
first	O
in	O
the	O
world	O
to	O
play	O
digital	O
music	O
.	O
</s>
<s>
The	O
CSIRAC	B-Device
was	O
constructed	O
by	O
a	O
team	O
led	O
by	O
Trevor	O
Pearcey	O
and	O
Maston	O
Beard	O
,	O
working	O
in	O
large	O
part	O
independently	O
of	O
similar	O
efforts	O
across	O
Europe	O
and	O
the	O
United	O
States	O
,	O
and	O
ran	O
its	O
first	O
test	O
program	O
(	O
multiplication	O
of	O
numbers	O
)	O
sometime	O
in	O
November	O
1949	O
.	O
</s>
<s>
It	O
used	O
mercury	O
acoustic	O
delay	O
lines	O
as	O
its	O
primary	O
data	O
storage	O
,	O
with	O
a	O
typical	O
capacity	O
of	O
768	O
20-bit	O
words	O
,	O
supplemented	O
by	O
a	O
parallel	O
disk-type	B-Device
device	I-Device
with	O
a	O
total	O
4096-word	O
capacity	O
and	O
an	O
access	O
time	O
of	O
10	O
milliseconds	O
.	O
</s>
<s>
Its	O
memory	O
clock	O
ran	O
at	O
1000Hz	O
,	O
and	O
the	O
control	B-General_Concept
unit	I-General_Concept
,	O
synchronized	O
to	O
the	O
clock	O
,	O
took	O
two	O
cycles	O
to	O
execute	O
an	O
instruction	O
(	O
later	O
the	O
speed	O
was	O
doubled	O
to	O
one	O
cycle	O
per	O
instruction	O
)	O
.	O
</s>
<s>
The	O
bus	B-General_Concept
(	O
termed	O
the	O
"	O
digit	O
trunk	O
"	O
in	O
their	O
design	O
)	O
is	O
unusual	O
compared	O
to	O
most	O
computers	O
in	O
that	O
it	O
was	O
serial	B-Protocol
—	O
it	O
transferred	O
one	O
bit	O
at	O
a	O
time	O
.	O
</s>
<s>
Most	O
of	O
CSIRAC	B-Device
's	O
approximately	O
2000	O
valves	O
were	O
of	O
the	O
types	O
6SN7	O
,	O
6V6	O
,	O
EA50	O
diodes	O
and	O
KT66	O
.	O
</s>
<s>
George	O
Semkiw	O
later	O
redesigned	O
the	O
drum-read	O
electronics	O
to	O
use	O
germanium	O
transistors	B-Application
.	O
</s>
<s>
Input	O
to	O
the	O
machine	O
was	O
performed	O
in	O
the	O
form	O
of	O
punched	O
paper	O
tape	O
,	O
after	O
experiments	O
with	O
punch	B-Architecture
cards	I-Architecture
proved	O
unsatisfactory	O
.	O
</s>
<s>
The	O
machine	O
was	O
controlled	O
through	O
a	O
console	O
which	O
allowed	O
programs	O
to	O
be	O
stepped	O
through	O
one	O
instruction	O
at	O
a	O
time	O
,	O
and	O
featured	O
CRT	B-Device
displays	I-Device
which	O
showed	O
the	O
contents	O
of	O
registers	O
.	O
</s>
<s>
The	O
instruction	B-General_Concept
set	I-General_Concept
supported	O
the	O
basic	B-Language
set	O
of	O
arithmetic	O
and	O
logical	O
operations	O
,	O
as	O
well	O
as	O
conditional	O
and	O
relative	O
jumps	O
(	O
making	O
it	O
possible	O
to	O
write	O
a	O
library	O
of	O
subroutines	O
)	O
.	O
</s>
<s>
The	O
machine	O
,	O
like	O
all	O
machines	O
of	O
the	O
era	O
,	O
had	O
no	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
It	O
was	O
similar	O
to	O
early	O
forms	O
of	O
BASIC	B-Language
,	O
which	O
was	O
designed	O
in	O
1963	O
for	O
the	O
20-bit	O
transistorized	O
GE-200	B-Device
series	I-Device
.	O
</s>
<s>
In	O
1950	O
CSIRAC	B-Device
was	O
used	O
to	O
play	O
music	O
,	O
the	O
first	O
known	O
use	O
of	O
a	O
digital	O
computer	O
for	O
the	O
purpose	O
.	O
</s>
<s>
In	O
1964	O
,	O
CSIRAC	B-Device
was	O
shut	O
down	O
for	O
the	O
last	O
time	O
.	O
</s>
<s>
It	O
has	O
not	O
been	O
operable	O
since	O
its	O
shutdown	O
,	O
but	O
many	O
of	O
the	O
programs	O
that	O
ran	O
on	O
it	O
have	O
been	O
preserved	O
,	O
and	O
an	O
emulator	B-Application
has	O
been	O
written	O
for	O
it	O
.	O
</s>
<s>
The	O
curators	O
have	O
decided	O
that	O
,	O
aside	O
from	O
the	O
cost	O
of	O
restoring	O
the	O
device	O
,	O
the	O
huge	O
number	O
of	O
repairs	O
that	O
would	O
be	O
required	O
to	O
make	O
it	O
safe	O
to	O
operate	O
(	O
CSIRAC	B-Device
used	O
30	O
kilowatts	O
of	O
power	O
in	O
operation	O
)	O
would	O
detract	O
from	O
its	O
historical	O
authenticity	O
.	O
</s>
<s>
CSIRAC	B-Device
is	O
listed	O
on	O
the	O
Victorian	O
Heritage	O
Register	O
and	O
is	O
included	O
in	O
a	O
Heritage	O
Overlay	O
.	O
</s>
