<s>
A	O
microcomputer	B-Architecture
is	O
a	O
small	O
,	O
relatively	O
inexpensive	O
computer	O
having	O
a	O
central	B-General_Concept
processing	I-General_Concept
unit	I-General_Concept
(	O
CPU	O
)	O
made	O
out	O
of	O
a	O
microprocessor	B-Architecture
.	O
</s>
<s>
The	O
computer	O
also	O
includes	O
memory	B-General_Concept
and	O
input/output	B-General_Concept
(	O
I/O	B-General_Concept
)	O
circuitry	O
together	O
mounted	O
on	O
a	O
printed	O
circuit	O
board	O
(	O
PCB	O
)	O
.	O
</s>
<s>
Microcomputers	B-Architecture
became	O
popular	O
in	O
the	O
1970s	O
and	O
1980s	O
with	O
the	O
advent	O
of	O
increasingly	O
powerful	O
microprocessors	B-Architecture
.	O
</s>
<s>
The	O
predecessors	O
to	O
these	O
computers	O
,	O
mainframes	B-Architecture
and	O
minicomputers	B-Architecture
,	O
were	O
comparatively	O
much	O
larger	O
and	O
more	O
expensive	O
(	O
though	O
indeed	O
present-day	O
mainframes	B-Architecture
such	O
as	O
the	O
IBM	B-Device
System	I-Device
z	I-Device
machines	O
use	O
one	O
or	O
more	O
custom	O
microprocessors	B-Architecture
as	O
their	O
CPUs	O
)	O
.	O
</s>
<s>
Many	O
microcomputers	B-Architecture
(	O
when	O
equipped	O
with	O
a	O
keyboard	B-Device
and	O
screen	B-Device
for	O
input	B-General_Concept
and	I-General_Concept
output	I-General_Concept
)	O
are	O
also	O
personal	B-Device
computers	I-Device
(	O
in	O
the	O
generic	O
sense	O
)	O
.	O
</s>
<s>
An	O
early	O
use	O
of	O
the	O
term	O
personal	B-Device
computer	I-Device
in	O
1962	O
predates	O
microprocessor-based	O
designs	O
.	O
</s>
<s>
(	O
See	O
"	O
Personal	B-Device
Computer	I-Device
:	O
Computers	O
at	O
Companies	O
"	O
reference	O
below	O
)	O
.	O
</s>
<s>
A	O
microcomputer	B-Architecture
used	O
as	O
an	O
embedded	B-Architecture
control	I-Architecture
system	O
may	O
have	O
no	O
human-readable	O
input	B-General_Concept
and	I-General_Concept
output	I-General_Concept
devices	O
.	O
</s>
<s>
"	O
Personal	B-Device
computer	I-Device
"	O
may	O
be	O
used	O
generically	O
or	O
may	O
denote	O
an	O
IBM	B-Device
PC	I-Device
compatible	O
machine	O
.	O
</s>
<s>
The	O
term	O
microcomputer	B-Architecture
came	O
into	O
popular	O
use	O
after	O
the	O
introduction	O
of	O
the	O
minicomputer	B-Architecture
,	O
although	O
Isaac	O
Asimov	O
used	O
the	O
term	O
in	O
his	O
short	O
story	O
"	O
The	O
Dying	O
Night	O
"	O
as	O
early	O
as	O
1956	O
(	O
published	O
in	O
The	O
Magazine	O
of	O
Fantasy	O
and	O
Science	O
Fiction	O
in	O
July	O
that	O
year	O
)	O
.	O
</s>
<s>
Most	O
notably	O
,	O
the	O
microcomputer	B-Architecture
replaced	O
the	O
many	O
separate	O
components	O
that	O
made	O
up	O
the	O
minicomputer	B-Architecture
's	O
CPU	O
with	O
one	O
integrated	O
microprocessor	B-Architecture
chip	O
.	O
</s>
<s>
To	O
answer	O
this	O
request	O
,	O
a	O
team	O
of	O
French	O
engineers	O
of	O
the	O
computer	O
technology	O
company	O
R2E	O
,	O
led	O
by	O
its	O
Head	O
of	O
Development	O
,	O
François	O
Gernelle	O
,	O
created	O
the	O
first	O
available	O
microprocessor-based	O
microcomputer	B-Architecture
,	O
the	O
Micral	B-Device
N	I-Device
.	O
The	O
same	O
year	O
the	O
company	O
filed	O
their	O
patents	O
with	O
the	O
term	O
"	O
Micro-ordinateur	O
"	O
,	O
a	O
literal	O
equivalent	O
of	O
"	O
Microcomputer	B-Architecture
"	O
,	O
to	O
designate	O
a	O
solid	O
state	O
machine	O
designed	O
with	O
a	O
microprocessor	B-Architecture
.	O
</s>
<s>
In	O
the	O
US	O
the	O
earliest	O
models	O
such	O
as	O
the	O
Altair	B-Architecture
8800	I-Architecture
were	O
often	O
sold	O
as	O
kits	O
to	O
be	O
assembled	O
by	O
the	O
user	O
,	O
and	O
came	O
with	O
as	O
little	O
as	O
256	O
bytes	B-Application
of	O
RAM	B-Architecture
,	O
and	O
no	O
input/output	B-General_Concept
devices	I-General_Concept
other	O
than	O
indicator	O
lights	O
and	O
switches	O
,	O
useful	O
as	O
a	O
proof	O
of	O
concept	O
to	O
demonstrate	O
what	O
such	O
a	O
simple	O
device	O
could	O
do	O
.	O
</s>
<s>
As	O
microprocessors	B-Architecture
and	O
semiconductor	B-Architecture
memory	I-Architecture
became	O
less	O
expensive	O
,	O
microcomputers	B-Architecture
grew	O
cheaper	O
and	O
easier	O
to	O
use	O
.	O
</s>
<s>
Increasingly	O
inexpensive	O
logic	O
chips	O
such	O
as	O
the	O
7400	O
series	O
allowed	O
cheap	O
dedicated	O
circuitry	O
for	O
improved	O
user	B-Application
interfaces	I-Application
such	O
as	O
keyboard	B-Device
input	O
,	O
instead	O
of	O
simply	O
a	O
row	O
of	O
switches	O
to	O
toggle	O
bits	O
one	O
at	O
a	O
time	O
.	O
</s>
<s>
Use	O
of	O
audio	B-Device
cassettes	I-Device
for	O
inexpensive	O
data	O
storage	O
replaced	O
manual	O
re-entry	O
of	O
a	O
program	O
every	O
time	O
the	O
device	O
was	O
powered	O
on	O
.	O
</s>
<s>
Large	O
cheap	O
arrays	O
of	O
silicon	O
logic	O
gates	O
in	O
the	O
form	O
of	O
read-only	B-Device
memory	I-Device
and	O
EPROMs	B-General_Concept
allowed	O
utility	O
programs	O
and	O
self-booting	O
kernels	B-Operating_System
to	O
be	O
stored	O
within	O
microcomputers	B-Architecture
.	O
</s>
<s>
Random-access	B-Architecture
memory	I-Architecture
became	O
cheap	O
enough	O
to	O
afford	O
dedicating	O
approximately	O
1	O
–	O
2	O
kilobytes	O
of	O
memory	B-General_Concept
to	O
a	O
video	B-General_Concept
display	I-General_Concept
controller	I-General_Concept
frame	B-Algorithm
buffer	I-Algorithm
,	O
for	O
a	O
40x25	O
or	O
80x25	O
text	O
display	O
or	O
blocky	O
color	O
graphics	O
on	O
a	O
common	O
household	O
television	O
.	O
</s>
<s>
This	O
replaced	O
the	O
slow	O
,	O
complex	O
,	O
and	O
expensive	O
teletypewriter	O
that	O
was	O
previously	O
common	O
as	O
an	O
interface	O
to	O
minicomputers	B-Architecture
and	O
mainframes	B-Architecture
.	O
</s>
<s>
A	O
large	O
number	O
of	O
computer	O
makers	O
packaged	O
microcomputers	B-Architecture
for	O
use	O
in	O
small	O
business	O
applications	O
.	O
</s>
<s>
By	O
1979	O
,	O
many	O
companies	O
such	O
as	O
Cromemco	O
,	O
Processor	O
Technology	O
,	O
IMSAI	O
,	O
North	O
Star	O
Computers	O
,	O
Southwest	O
Technical	O
Products	O
Corporation	O
,	O
Ohio	B-Application
Scientific	I-Application
,	O
Altos	O
Computer	O
Systems	O
,	O
Morrow	O
Designs	O
and	O
others	O
produced	O
systems	O
designed	O
for	O
resourceful	O
end	O
users	O
or	O
consulting	O
firms	O
to	O
deliver	O
business	O
systems	O
such	O
as	O
accounting	O
,	O
database	O
management	O
and	O
word	O
processing	O
to	O
small	O
businesses	O
.	O
</s>
<s>
This	O
allowed	O
businesses	O
unable	O
to	O
afford	O
leasing	O
of	O
a	O
minicomputer	B-Architecture
or	O
time-sharing	B-General_Concept
service	O
the	O
opportunity	O
to	O
automate	O
business	O
functions	O
,	O
without	O
(	O
usually	O
)	O
hiring	O
a	O
full-time	O
staff	O
to	O
operate	O
the	O
computers	O
.	O
</s>
<s>
A	O
representative	O
system	O
of	O
this	O
era	O
would	O
have	O
used	O
an	O
S100	B-Architecture
bus	I-Architecture
,	O
an	O
8-bit	O
processor	O
such	O
as	O
an	O
Intel	B-General_Concept
8080	I-General_Concept
or	O
Zilog	B-General_Concept
Z80	I-General_Concept
,	O
and	O
either	O
CP/M	B-Application
or	O
MP/M	B-Operating_System
operating	O
system	O
.	O
</s>
<s>
The	O
increasing	O
availability	O
and	O
power	O
of	O
desktop	B-Device
computers	I-Device
for	O
personal	O
use	O
attracted	O
the	O
attention	O
of	O
more	O
software	O
developers	O
.	O
</s>
<s>
As	O
the	O
industry	O
matured	O
,	O
the	O
market	O
for	O
personal	B-Device
computers	I-Device
standardized	O
around	O
IBM	B-Device
PC	I-Device
compatibles	O
running	O
DOS	B-Device
,	O
and	O
later	O
Windows	B-Application
.	O
</s>
<s>
Modern	O
desktop	B-Device
computers	I-Device
,	O
video	B-Device
game	I-Device
consoles	I-Device
,	O
laptops	B-Device
,	O
tablet	B-Device
PCs	I-Device
,	O
and	O
many	O
types	O
of	O
handheld	B-Application
devices	I-Application
,	O
including	O
mobile	O
phones	O
,	O
pocket	O
calculators	B-Application
,	O
and	O
industrial	O
embedded	B-Architecture
systems	I-Architecture
,	O
may	O
all	O
be	O
considered	O
examples	O
of	O
microcomputers	B-Architecture
according	O
to	O
the	O
definition	O
given	O
above	O
.	O
</s>
<s>
By	O
the	O
early	O
2000s	O
,	O
everyday	O
use	O
of	O
the	O
expression	O
"	O
microcomputer	B-Architecture
"	O
(	O
and	O
in	O
particular	O
"	O
micro	O
"	O
)	O
declined	O
significantly	O
from	O
its	O
peak	O
in	O
the	O
mid-1980s	O
.	O
</s>
<s>
The	O
term	O
is	O
most	O
commonly	O
associated	O
with	O
the	O
most	O
popular	O
all-in-one	O
8-bit	O
home	O
computers	O
(	O
such	O
as	O
the	O
Apple	B-Device
II	I-Device
,	O
ZX	B-Operating_System
Spectrum	I-Operating_System
,	O
Commodore	O
64	O
,	O
BBC	B-Device
Micro	I-Device
,	O
and	O
TRS-80	B-Device
)	O
and	O
small-business	O
CP/M	B-Application
-based	O
microcomputers	B-Architecture
.	O
</s>
<s>
In	O
colloquial	O
usage	O
,	O
"	O
microcomputer	B-Architecture
"	O
has	O
been	O
largely	O
supplanted	O
by	O
the	O
term	O
"	O
personal	B-Device
computer	I-Device
"	O
or	O
"	O
PC	O
"	O
,	O
which	O
specifies	O
a	O
computer	O
that	O
has	O
been	O
designed	O
to	O
be	O
used	O
by	O
one	O
individual	O
at	O
a	O
time	O
,	O
a	O
term	O
first	O
coined	O
in	O
1959	O
.	O
</s>
<s>
IBM	O
first	O
promoted	O
the	O
term	O
"	O
personal	B-Device
computer	I-Device
"	O
to	O
differentiate	O
the	O
IBM	B-Device
PC	I-Device
from	O
CP/M	B-Application
-based	O
microcomputers	B-Architecture
likewise	O
targeted	O
at	O
the	O
small-business	O
market	O
,	O
and	O
also	O
IBM	O
's	O
own	O
mainframes	B-Architecture
and	O
minicomputers	B-Architecture
.	O
</s>
<s>
However	O
,	O
following	O
its	O
release	O
,	O
the	O
IBM	B-Device
PC	I-Device
itself	O
was	O
widely	O
imitated	O
,	O
as	O
well	O
as	O
the	O
term	O
.	O
</s>
<s>
The	O
component	O
parts	O
were	O
commonly	O
available	O
to	O
producers	O
and	O
the	O
BIOS	B-Operating_System
was	O
reverse	O
engineered	O
through	O
cleanroom	O
design	O
techniques	O
.	O
</s>
<s>
IBM	B-Device
PC	I-Device
compatible	O
"	O
clones	O
"	O
became	O
commonplace	O
,	O
and	O
the	O
terms	O
"	O
personal	B-Device
computer	I-Device
"	O
,	O
and	O
especially	O
"	O
PC	O
"	O
,	O
stuck	O
with	O
the	O
general	O
public	O
,	O
often	O
specifically	O
for	O
a	O
computer	O
compatible	O
with	O
DOS	B-Device
(	O
or	O
nowadays	O
Windows	B-Application
)	O
.	O
</s>
<s>
Monitors	B-Device
,	O
keyboards	B-Device
and	O
other	O
devices	O
for	O
input	B-General_Concept
and	I-General_Concept
output	I-General_Concept
may	O
be	O
integrated	O
or	O
separate	O
.	O
</s>
<s>
Computer	B-General_Concept
memory	I-General_Concept
in	O
the	O
form	O
of	O
RAM	B-Architecture
,	O
and	O
at	O
least	O
one	O
other	O
less	O
volatile	O
,	O
memory	B-General_Concept
storage	O
device	O
are	O
usually	O
combined	O
with	O
the	O
CPU	O
on	O
a	O
system	B-Architecture
bus	I-Architecture
in	O
one	O
unit	O
.	O
</s>
<s>
Other	O
devices	O
that	O
make	O
up	O
a	O
complete	O
microcomputer	B-Architecture
system	O
include	O
batteries	O
,	O
a	O
power	O
supply	O
unit	O
,	O
a	O
keyboard	B-Device
and	O
various	O
input/output	B-General_Concept
devices	I-General_Concept
used	O
to	O
convey	O
information	O
to	O
and	O
from	O
a	O
human	O
operator	O
(	O
printers	O
,	O
monitors	B-Device
,	O
human	B-General_Concept
interface	I-General_Concept
devices	I-General_Concept
)	O
.	O
</s>
<s>
Microcomputers	B-Architecture
are	O
designed	O
to	O
serve	O
only	O
one	O
user	O
at	O
a	O
time	O
,	O
although	O
they	O
can	O
often	O
be	O
modified	O
with	O
software	O
or	O
hardware	O
to	O
concurrently	O
serve	O
more	O
than	O
one	O
user	O
.	O
</s>
<s>
Microcomputers	B-Architecture
fit	O
well	O
on	O
or	O
under	O
desks	O
or	O
tables	O
,	O
so	O
that	O
they	O
are	O
within	O
easy	O
access	O
of	O
users	O
.	O
</s>
<s>
Bigger	O
computers	O
like	O
minicomputers	B-Architecture
,	O
mainframes	B-Architecture
,	O
and	O
supercomputers	B-Architecture
take	O
up	O
large	O
cabinets	O
or	O
even	O
dedicated	O
rooms	O
.	O
</s>
<s>
A	O
microcomputer	B-Architecture
comes	O
equipped	O
with	O
at	O
least	O
one	O
type	O
of	O
data	O
storage	O
,	O
usually	O
RAM	B-Architecture
.	O
</s>
<s>
Although	O
some	O
microcomputers	B-Architecture
(	O
particularly	O
early	O
8-bit	O
home	O
micros	O
)	O
perform	O
tasks	O
using	O
RAM	B-Architecture
alone	O
,	O
some	O
form	O
of	O
secondary	O
storage	O
is	O
normally	O
desirable	O
.	O
</s>
<s>
Later	O
,	O
secondary	O
storage	O
(	O
particularly	O
in	O
the	O
form	O
of	O
floppy	B-Device
disk	I-Device
and	O
hard	B-Device
disk	I-Device
drives	I-Device
)	O
were	O
built	O
into	O
the	O
microcomputer	B-Architecture
case	O
.	O
</s>
<s>
Although	O
they	O
did	O
not	O
contain	O
any	O
microprocessors	B-Architecture
,	O
but	O
were	O
built	O
around	O
transistor-transistor	B-General_Concept
logic	I-General_Concept
(	O
TTL	B-General_Concept
)	O
,	O
Hewlett-Packard	O
calculators	B-Application
as	O
far	O
back	O
as	O
1968	O
had	O
various	O
levels	O
of	O
programmability	O
comparable	O
to	O
microcomputers	B-Architecture
.	O
</s>
<s>
The	O
programming	O
language	O
resembled	O
assembly	B-Language
language	I-Language
in	O
many	O
ways	O
.	O
</s>
<s>
The	O
HP	B-Device
9100A	I-Device
was	O
referred	O
to	O
as	O
a	O
personal	B-Device
computer	I-Device
in	O
an	O
advertisement	O
in	O
a	O
1968	O
Science	O
magazine	O
,	O
but	O
that	O
advertisement	O
was	O
quickly	O
dropped	O
.	O
</s>
<s>
HP	O
was	O
reluctant	O
to	O
sell	O
them	O
as	O
"	O
computers	O
"	O
because	O
the	O
perception	O
at	O
that	O
time	O
was	O
that	O
a	O
computer	O
had	O
to	O
be	O
big	O
in	O
size	O
to	O
be	O
powerful	O
,	O
and	O
thus	O
decided	O
to	O
market	O
them	O
as	O
calculators	B-Application
.	O
</s>
<s>
Additionally	O
,	O
at	O
that	O
time	O
,	O
people	O
were	O
more	O
likely	O
to	O
buy	O
calculators	B-Application
than	O
computers	O
,	O
and	O
,	O
purchasing	O
agents	O
also	O
preferred	O
the	O
term	O
"	O
calculator	B-Application
"	O
because	O
purchasing	O
a	O
"	O
computer	O
"	O
required	O
additional	O
layers	O
of	O
purchasing	O
authority	O
approvals	O
.	O
</s>
<s>
The	O
Datapoint	B-Device
2200	I-Device
,	O
made	O
by	O
CTC	O
in	O
1970	O
,	O
was	O
also	O
comparable	O
to	O
microcomputers	B-Architecture
.	O
</s>
<s>
While	O
it	O
contains	O
no	O
microprocessor	B-Architecture
,	O
the	O
instruction	B-General_Concept
set	I-General_Concept
of	O
its	O
custom	O
TTL	B-General_Concept
processor	O
was	O
the	O
basis	O
of	O
the	O
instruction	B-General_Concept
set	I-General_Concept
for	O
the	O
Intel	B-General_Concept
8008	I-General_Concept
,	O
and	O
for	O
practical	O
purposes	O
the	O
system	O
behaves	O
approximately	O
as	O
if	O
it	O
contains	O
an	O
8008	B-General_Concept
.	O
</s>
<s>
This	O
is	O
because	O
Intel	O
was	O
the	O
contractor	O
in	O
charge	O
of	O
developing	O
the	O
Datapoint	O
's	O
CPU	O
,	O
but	O
ultimately	O
CTC	O
rejected	O
the	O
8008	B-General_Concept
design	O
because	O
it	O
needed	O
20	O
support	O
chips	O
.	O
</s>
<s>
Another	O
early	O
system	O
,	O
the	O
Kenbak-1	B-Device
,	O
was	O
released	O
in	O
1971	O
.	O
</s>
<s>
Like	O
the	O
Datapoint	B-Device
2200	I-Device
,	O
it	O
used	O
small-scale	O
integrated	O
transistor	B-General_Concept
–	I-General_Concept
transistor	I-General_Concept
logic	I-General_Concept
instead	O
of	O
a	O
microprocessor	B-Architecture
.	O
</s>
<s>
In	O
late	O
1972	O
,	O
a	O
French	O
team	O
headed	O
by	O
François	O
Gernelle	O
within	O
a	O
small	O
company	O
,	O
Réalisations	O
&	O
Etudes	O
Electroniques	O
(	O
R2E	O
)	O
,	O
developed	O
and	O
patented	O
a	O
computer	O
based	O
on	O
a	O
microprocessor	B-Architecture
–	O
the	O
Intel	B-General_Concept
8008	I-General_Concept
8-bit	O
microprocessor	B-Architecture
.	O
</s>
<s>
This	O
Micral-N	B-Device
was	O
marketed	O
in	O
early	O
1973	O
as	O
a	O
"	O
Micro-ordinateur	O
"	O
or	O
microcomputer	B-Architecture
,	O
mainly	O
for	O
scientific	O
and	O
process-control	O
applications	O
.	O
</s>
<s>
About	O
a	O
hundred	O
Micral-N	B-Device
were	O
installed	O
in	O
the	O
next	O
two	O
years	O
,	O
followed	O
by	O
a	O
new	O
version	O
based	O
on	O
the	O
Intel	B-General_Concept
8080	I-General_Concept
.	O
</s>
<s>
The	O
first	O
version	O
was	O
based	O
on	O
LSI	O
chips	O
with	O
an	O
Intel	B-General_Concept
8008	I-General_Concept
as	O
peripheral	O
controller	O
(	O
keyboard	B-Device
,	O
monitor	O
and	O
printer	O
)	O
,	O
before	O
adopting	O
the	O
Zilog	B-General_Concept
Z80	I-General_Concept
as	O
main	O
processor	O
.	O
</s>
<s>
In	O
late	O
1972	O
,	O
a	O
Sacramento	O
State	O
University	O
team	O
led	O
by	O
Bill	O
Pentz	O
built	O
the	O
Sac	O
State	O
8008	B-General_Concept
computer	O
,	O
able	O
to	O
handle	O
thousands	O
of	O
patients	O
 '	O
medical	O
records	O
.	O
</s>
<s>
The	O
Sac	O
State	O
8008	B-General_Concept
was	O
designed	O
with	O
the	O
Intel	B-General_Concept
8008	I-General_Concept
.	O
</s>
<s>
It	O
had	O
a	O
full	O
set	O
of	O
hardware	O
and	O
software	O
components	O
:	O
a	O
disk	O
operating	O
system	O
included	O
in	O
a	O
series	O
of	O
programmable	O
read-only	B-Device
memory	I-Device
chips	O
(	O
PROMs	O
)	O
;	O
8	O
Kilobytes	O
of	O
RAM	B-Architecture
;	O
IBM	O
's	O
Basic	O
Assembly	B-Language
Language	I-Language
(	O
BAL	O
)	O
;	O
a	O
hard	B-Device
drive	I-Device
;	O
a	O
color	O
display	O
;	O
a	O
printer	O
output	O
;	O
a	O
150	O
bit/s	O
serial	O
interface	O
for	O
connecting	O
to	O
a	O
mainframe	B-Architecture
;	O
and	O
even	O
the	O
world	O
's	O
first	O
microcomputer	B-Architecture
front	O
panel	O
.	O
</s>
<s>
In	O
early	O
1973	O
,	O
Sord	O
Computer	O
Corporation	O
(	O
now	O
Toshiba	O
Personal	B-Device
Computer	I-Device
System	O
Corporation	O
)	O
completed	O
the	O
SMP80/08	O
,	O
which	O
used	O
the	O
Intel	B-General_Concept
8008	I-General_Concept
microprocessor	B-Architecture
.	O
</s>
<s>
After	O
the	O
first	O
general-purpose	O
microprocessor	B-Architecture
,	O
the	O
Intel	B-General_Concept
8080	I-General_Concept
,	O
was	O
announced	O
in	O
April	O
1974	O
,	O
Sord	O
announced	O
the	O
SMP80/x	O
,	O
the	O
first	O
microcomputer	B-Architecture
to	O
use	O
the	O
8080	B-General_Concept
,	O
in	O
May	O
1974	O
.	O
</s>
<s>
Virtually	O
all	O
early	O
microcomputers	B-Architecture
were	O
essentially	O
boxes	O
with	O
lights	O
and	O
switches	O
;	O
one	O
had	O
to	O
read	O
and	O
understand	O
binary	O
numbers	O
and	O
machine	O
language	O
to	O
program	O
and	O
use	O
them	O
(	O
the	O
Datapoint	B-Device
2200	I-Device
was	O
a	O
striking	O
exception	O
,	O
bearing	O
a	O
modern	O
design	O
based	O
on	O
a	O
monitor	O
,	O
keyboard	B-Device
,	O
and	O
tape	O
and	O
disk	O
drives	O
)	O
.	O
</s>
<s>
Of	O
the	O
early	O
"	O
box	O
of	O
switches	O
"	O
-type	O
microcomputers	B-Architecture
,	O
the	O
MITS	B-Architecture
Altair	I-Architecture
8800	I-Architecture
(	O
1975	O
)	O
was	O
arguably	O
the	O
most	O
famous	O
.	O
</s>
<s>
Most	O
of	O
these	O
simple	O
,	O
early	O
microcomputers	B-Architecture
were	O
sold	O
as	O
electronic	O
kits	O
—	O
bags	O
full	O
of	O
loose	O
components	O
which	O
the	O
buyer	O
had	O
to	O
solder	O
together	O
before	O
the	O
system	O
could	O
be	O
used	O
.	O
</s>
<s>
The	O
period	O
from	O
about	O
1971	O
to	O
1976	O
is	O
sometimes	O
called	O
the	O
first	O
generation	O
of	O
microcomputers	B-Architecture
.	O
</s>
<s>
Many	O
companies	O
such	O
as	O
DEC	O
,	O
National	O
Semiconductor	O
,	O
Texas	O
Instruments	O
offered	O
their	O
microcomputers	B-Architecture
for	O
use	O
in	O
terminal	O
control	O
,	O
peripheral	O
device	O
interface	O
control	O
and	O
industrial	O
machine	O
control	O
.	O
</s>
<s>
In	O
1975	O
,	O
the	O
Processor	O
Technology	O
SOL-20	B-Architecture
was	O
designed	O
,	O
which	O
consisted	O
of	O
one	O
board	O
which	O
included	O
all	O
the	O
parts	O
of	O
the	O
computer	O
system	O
.	O
</s>
<s>
The	O
SOL-20	B-Architecture
had	O
built-in	O
EPROM	B-General_Concept
software	O
which	O
eliminated	O
the	O
need	O
for	O
rows	O
of	O
switches	O
and	O
lights	O
.	O
</s>
<s>
The	O
MITS	B-Architecture
Altair	I-Architecture
just	O
mentioned	O
played	O
an	O
instrumental	O
role	O
in	O
sparking	O
significant	O
hobbyist	O
interest	O
,	O
which	O
itself	O
eventually	O
led	O
to	O
the	O
founding	O
and	O
success	O
of	O
many	O
well-known	O
personal	B-Device
computer	I-Device
hardware	O
and	O
software	O
companies	O
,	O
such	O
as	O
Microsoft	O
and	O
Apple	O
Computer	O
.	O
</s>
<s>
By	O
1977	O
,	O
the	O
introduction	O
of	O
the	O
second	O
microcomputer	B-Architecture
generation	O
as	O
consumer	O
goods	O
,	O
known	O
as	O
home	O
computers	O
,	O
made	O
them	O
considerably	O
easier	O
to	O
use	O
than	O
their	O
predecessors	O
because	O
their	O
predecessors	O
 '	O
operation	O
often	O
demanded	O
thorough	O
familiarity	O
with	O
practical	O
electronics	O
.	O
</s>
<s>
The	O
ability	O
to	O
connect	O
to	O
a	O
monitor	O
(	O
screen	B-Device
)	O
or	O
TV	O
set	O
allowed	O
visual	O
manipulation	O
of	O
text	O
and	O
numbers	O
.	O
</s>
<s>
These	O
features	O
were	O
already	O
common	O
in	O
minicomputers	B-Architecture
,	O
with	O
which	O
many	O
hobbyists	O
and	O
early	O
produces	O
were	O
familiar	O
.	O
</s>
<s>
In	O
1979	O
,	O
the	O
launch	O
of	O
the	O
VisiCalc	B-Application
spreadsheet	B-Application
(	O
initially	O
for	O
the	O
Apple	B-Device
II	I-Device
)	O
first	O
turned	O
the	O
microcomputer	B-Architecture
from	O
a	O
hobby	O
for	O
computer	O
enthusiasts	O
into	O
a	O
business	O
tool	O
.	O
</s>
<s>
After	O
the	O
1981	O
release	O
by	O
IBM	O
of	O
its	O
IBM	B-Device
PC	I-Device
,	O
the	O
term	O
personal	B-Device
computer	I-Device
became	O
generally	O
used	O
for	O
microcomputers	B-Architecture
compatible	O
with	O
the	O
IBM	B-Device
PC	I-Device
architecture	O
(	O
PC	O
compatible	O
)	O
.	O
</s>
