<s>
A	O
transistor	B-Device
computer	I-Device
,	O
now	O
often	O
called	O
a	O
second-generation	O
computer	O
,	O
is	O
a	O
computer	O
which	O
uses	O
discrete	O
transistors	B-Application
instead	O
of	O
vacuum	O
tubes	O
.	O
</s>
<s>
A	O
second-generation	O
computer	O
,	O
through	O
the	O
late	O
1950s	O
and	O
1960s	O
featured	O
circuit	O
boards	O
filled	O
with	O
individual	O
transistors	B-Application
and	O
magnetic-core	O
memory	O
.	O
</s>
<s>
The	O
University	O
of	O
Manchester	O
's	O
experimental	O
Transistor	B-Device
Computer	I-Device
was	O
first	O
operational	O
in	O
November	O
1953	O
and	O
it	O
is	O
widely	O
believed	O
to	O
be	O
the	O
first	O
transistor	B-Device
computer	I-Device
to	O
come	O
into	O
operation	O
anywhere	O
in	O
the	O
world	O
.	O
</s>
<s>
There	O
were	O
two	O
versions	O
of	O
the	O
Transistor	B-Device
Computer	I-Device
,	O
the	O
prototype	O
,	O
operational	O
in	O
1953	O
,	O
and	O
the	O
full-size	O
version	O
,	O
commissioned	O
in	O
April	O
1955	O
.	O
</s>
<s>
The	O
1953	O
machine	O
had	O
92	O
point-contact	O
transistors	B-Application
and	O
550	O
diodes	O
,	O
manufactured	O
by	O
STC	O
.	O
</s>
<s>
The	O
1955	O
machine	O
had	O
a	O
total	O
of	O
200	O
point-contact	O
transistors	B-Application
and	O
1,300	O
point	O
diodes	O
,	O
which	O
resulted	O
in	O
a	O
power	O
consumption	O
of	O
150	O
watts	O
.	O
</s>
<s>
There	O
were	O
considerable	O
reliability	O
problems	O
with	O
the	O
early	O
batches	O
of	O
transistors	B-Application
and	O
the	O
average	O
error-free	O
run	O
in	O
1955	O
was	O
only	O
1.5	O
hours	O
.	O
</s>
<s>
The	O
Transistor	B-Device
Computer	I-Device
also	O
used	O
a	O
small	O
number	O
of	O
tubes	O
in	O
its	O
clock	O
generator	O
,	O
so	O
it	O
was	O
not	O
the	O
first	O
fully	O
transistorized	O
machine	O
.	O
</s>
<s>
The	O
design	O
of	O
a	O
full-size	O
Transistor	B-Device
Computer	I-Device
was	O
subsequently	O
adopted	O
by	O
the	O
Manchester	O
firm	O
of	O
Metropolitan-Vickers	O
,	O
who	O
changed	O
all	O
the	O
circuits	O
to	O
use	O
more	O
reliable	O
junction	O
transistors	B-Application
.	O
</s>
<s>
The	O
production	O
version	O
was	O
known	O
as	O
the	O
Metrovick	B-Device
950	I-Device
and	O
was	O
built	O
from	O
1956	O
to	O
the	O
extent	O
of	O
six	O
or	O
seven	O
machines	O
,	O
which	O
were	O
"	O
used	O
commercially	O
within	O
the	O
company	O
"	O
or	O
"	O
mainly	O
for	O
internal	O
use	O
"	O
.	O
</s>
<s>
These	O
included	O
the	O
Bell	O
Laboratories	O
TRADIC	B-Device
,	O
completed	O
in	O
January	O
1954	O
,	O
which	O
used	O
a	O
single	O
high-power	O
output	O
vacuum-tube	O
amplifier	O
to	O
supply	O
its	O
1-MHz	O
clock	O
power	O
.	O
</s>
<s>
The	O
first	O
fully	O
transistorized	B-Device
computer	I-Device
was	O
either	O
the	O
Harwell	B-Device
CADET	I-Device
,	O
which	O
first	O
operated	O
in	O
February	O
1955	O
,	O
although	O
the	O
price	O
paid	O
for	O
this	O
was	O
that	O
it	O
operated	O
only	O
at	O
the	O
slow	O
speed	O
of	O
58kHz	O
,	O
or	O
the	O
prototype	O
IBM	B-Device
604	I-Device
transistor	B-Application
calculator	O
.	O
</s>
<s>
The	O
Burroughs	O
Corporation	O
claimed	O
the	O
SM-65	O
Atlas	O
ICBM	O
/	O
THOR	O
ABLE	O
guidance	O
computer	O
(	O
MOD	O
1	O
)	O
that	O
it	O
delivered	O
to	O
the	O
US	O
Air	O
Force	O
at	O
the	O
Cape	O
Canaveral	O
missile	O
range	O
in	O
June	O
1957	O
was	O
"	O
the	O
world	O
's	O
first	O
operational	O
transistorized	B-Device
computer	I-Device
"	O
.	O
</s>
<s>
MIT	O
's	O
Lincoln	O
Laboratory	O
started	O
developing	O
a	O
transistorized	B-Device
computer	I-Device
the	O
TX-0	B-Device
in	O
1956	O
.	O
</s>
<s>
Further	O
transistorized	B-Device
computers	I-Device
became	O
operational	O
in	O
Japan	O
(	O
ETL	O
Mark	O
III	O
,	O
July	O
1956	O
)	O
,	O
in	O
Canada	O
(	O
DRTE	B-Device
Computer	I-Device
,	O
1957	O
)	O
,	O
and	O
in	O
Austria	O
,	O
(	O
Mailüfterl	B-Device
,	O
May	O
1958	O
)	O
,	O
these	O
being	O
the	O
first	O
transistorized	B-Device
computers	I-Device
in	O
Asia	O
,	O
Canada	O
and	O
mainland	O
Europe	O
respectively	O
.	O
</s>
<s>
In	O
April	O
1955	O
,	O
IBM	O
announced	O
the	O
IBM	B-Device
608	I-Device
transistor	B-Application
calculator	O
,	O
which	O
was	O
first	O
shipped	O
in	O
December	O
1957	O
.	O
</s>
<s>
IBM	O
and	O
several	O
historians	O
thus	O
consider	O
the	O
IBM	B-Device
608	I-Device
the	O
first	O
all	O
solid-state	O
computing	O
machine	O
commercially	O
marketed	O
.	O
</s>
<s>
The	O
development	O
of	O
the	O
608	O
was	O
preceded	O
by	O
the	O
prototyping	O
of	O
an	O
experimental	O
all-transistor	O
version	O
of	O
the	O
604	O
.	O
</s>
<s>
The	O
Philco	B-Device
Transac	I-Device
models	O
S-1000	O
scientific	O
computer	O
and	O
S-2000	O
electronic	O
data	O
processing	O
computer	O
were	O
early	O
commercially	O
produced	O
large-scale	O
all-transistor	O
computers	O
;	O
they	O
were	O
announced	O
in	O
1957	O
but	O
did	O
not	O
ship	O
until	O
sometime	O
after	O
the	O
fall	O
of	O
1958	O
.	O
</s>
<s>
The	O
Philco	O
computer	O
name	O
"	O
Transac	B-Device
"	O
stands	O
for	O
Transistor-Automatic-Computer	O
.	O
</s>
<s>
Both	O
of	O
these	O
Philco	B-Device
computer	I-Device
models	I-Device
used	O
the	O
surface-barrier	O
transistor	B-Application
in	O
their	O
circuitry	O
designs	O
,	O
the	O
world	O
's	O
first	O
high-frequency	O
transistor	B-Application
suitable	O
for	O
high-speed	O
computers	O
.	O
</s>
<s>
The	O
surface-barrier	O
transistor	B-Application
was	O
developed	O
by	O
Philco	O
in	O
1953	O
.	O
</s>
<s>
RCA	O
shipped	O
the	O
RCA	B-Device
501	I-Device
its	O
first	O
all	O
transistor	B-Device
computer	I-Device
in	O
1958	O
.	O
</s>
<s>
In	O
Italy	O
,	O
Olivetti	O
's	O
first	O
commercial	O
fully	O
transistorized	B-Device
computer	I-Device
was	O
the	O
Olivetti	B-Operating_System
Elea	I-Operating_System
9003	O
,	O
sold	O
from	O
1959	O
.	O
</s>
<s>
IBM	O
,	O
which	O
dominated	O
the	O
data	O
processing	O
industry	O
through	O
most	O
of	O
the	O
20th	O
century	O
,	O
introduced	O
its	O
first	O
commercial	O
transistorized	B-Device
computers	I-Device
beginning	O
in	O
1958	O
,	O
with	O
the	O
IBM	B-Device
7070	I-Device
,	O
a	O
ten-digit-word	O
decimal	O
machine	O
.	O
</s>
<s>
It	O
was	O
followed	O
in	O
1959	O
by	O
the	O
IBM	B-Device
7090	I-Device
,	O
a	O
36-bit	O
scientific	O
machine	O
,	O
the	O
highly	O
popular	O
IBM	B-Device
1401	I-Device
designed	O
to	O
replace	O
punched	O
card	O
tabulating	O
machines	O
,	O
and	O
the	O
desk-sized	O
1620	B-Device
,	O
a	O
variable	O
length	O
decimal	O
machine	O
.	O
</s>
<s>
IBM	O
's	O
7000	B-Device
and	O
1400	B-Device
series	O
included	O
many	O
variants	O
on	O
these	O
designs	O
,	O
with	O
different	O
data	O
formats	O
,	O
instruction	O
sets	O
and	O
even	O
different	O
character	O
encodings	O
,	O
but	O
all	O
were	O
built	O
using	O
the	O
same	O
series	O
of	O
electronics	O
modules	O
,	O
the	O
IBM	B-Device
Standard	I-Device
Modular	I-Device
System	I-Device
(	O
SMS	O
)	O
.	O
</s>
<s>
Developers	O
of	O
the	O
TX-0	B-Device
left	O
to	O
form	O
the	O
Digital	O
Equipment	O
Corporation	O
in	O
1957	O
.	O
</s>
<s>
Transistorized	O
from	O
the	O
beginning	O
,	O
early	O
DEC	O
products	O
included	O
the	O
PDP-1	B-Device
,	O
PDP-6	B-Device
,	O
PDP-7	B-Device
and	O
early	O
PDP-8s	B-Device
,	O
the	O
last	O
starting	O
the	O
minicomputer	B-Architecture
revolution	O
.	O
</s>
<s>
In	O
1964	O
,	O
IBM	O
announced	O
its	O
System/360	B-Application
,	O
a	O
collection	O
of	O
computers	O
covering	O
a	O
wide	O
range	O
of	O
capabilities	O
and	O
prices	O
with	O
a	O
unified	O
architecture	O
,	O
to	O
replace	O
its	O
earlier	O
computers	O
.	O
</s>
<s>
Unwilling	O
to	O
bet	O
the	O
company	O
on	O
the	O
immature	O
monolithic	O
IC	O
technology	O
of	O
the	O
early	O
1960s	O
,	O
IBM	O
built	O
the	O
S/360	B-Application
series	O
using	O
IBM	B-Algorithm
's	I-Algorithm
Solid	I-Algorithm
Logic	I-Algorithm
Technology	I-Algorithm
(	O
SLT	O
)	O
modules	O
.	O
</s>
<s>
SLT	O
could	O
package	O
several	O
individual	O
transistors	B-Application
and	O
individual	O
diodes	O
with	O
deposited	O
resistors	O
and	O
interconnections	O
in	O
a	O
module	O
one-half	O
inch	O
square	O
,	O
roughly	O
the	O
equivalent	O
logic	O
of	O
the	O
earlier	O
IBM	B-Device
Standard	I-Device
Modular	I-Device
System	I-Device
card	O
,	O
but	O
unlike	O
monolithic	O
IC	O
manufacturing	O
,	O
the	O
diodes	O
and	O
transistors	B-Application
in	O
an	O
SLT	O
module	O
were	O
individually	O
placed	O
and	O
connected	O
at	O
the	O
end	O
of	O
each	O
module	O
's	O
assembly	O
.	O
</s>
<s>
First	B-Architecture
generation	I-Architecture
computers	I-Architecture
were	O
largely	O
out	O
of	O
reach	O
of	O
schools	O
and	O
hobbyists	O
who	O
wished	O
to	O
build	O
their	O
own	O
,	O
largely	O
because	O
of	O
the	O
cost	O
of	O
the	O
large	O
number	O
of	O
vacuum	O
tubes	O
required	O
(	O
though	O
relay-based	O
computer	O
projects	O
were	O
undertaken	O
)	O
.	O
</s>
<s>
So	O
,	O
second	O
and	O
third	O
generation	O
computer	O
design	O
(	O
transistors	B-Application
and	O
LSI	O
)	O
were	O
perhaps	O
the	O
best	O
suited	O
to	O
being	O
undertaken	O
by	O
schools	O
and	O
hobbyists	O
.	O
</s>
