<s>
The	O
Intel	O
8008	O
(	O
"	O
eight-thousand-eight	O
"	O
or	O
"	O
eighty-oh-eight	O
"	O
)	O
is	O
an	O
early	O
byte-oriented	O
microprocessor	B-Architecture
designed	O
by	O
Computer	B-General_Concept
Terminal	I-General_Concept
Corporation	O
(	O
CTC	O
)	O
,	O
implemented	O
and	O
manufactured	O
by	O
Intel	O
,	O
and	O
introduced	O
in	O
April	O
1972	O
.	O
</s>
<s>
Originally	O
known	O
as	O
the	O
1201	O
,	O
the	O
chip	O
was	O
commissioned	O
by	O
Computer	B-General_Concept
Terminal	I-General_Concept
Corporation	O
(	O
CTC	O
)	O
to	O
implement	O
an	O
instruction	O
set	O
of	O
their	O
design	O
for	O
their	O
Datapoint	B-Device
2200	I-Device
programmable	O
terminal	O
.	O
</s>
<s>
As	O
the	O
chip	O
was	O
delayed	O
and	O
did	O
not	O
meet	O
CTC	O
's	O
performance	O
goals	O
,	O
the	O
2200	O
ended	O
up	O
using	O
CTC	O
's	O
own	O
TTL-based	O
CPU	O
instead	O
.	O
</s>
<s>
An	O
agreement	O
permitted	O
Intel	O
to	O
market	O
the	O
chip	O
to	O
other	O
customers	O
after	O
Seiko	O
expressed	O
an	O
interest	O
in	O
using	O
it	O
for	O
a	O
calculator	B-Application
.	O
</s>
<s>
However	O
,	O
given	O
the	O
immaturity	O
of	O
the	O
market	O
,	O
the	O
company	O
's	O
business	O
plan	O
mentioned	O
only	O
a	O
Teletype	B-Application
Model	I-Application
33	I-Application
ASR	O
replacement	O
,	O
which	O
shipped	O
as	O
the	O
Datapoint	B-Device
3300	I-Device
.	O
</s>
<s>
The	O
case	O
was	O
deliberately	O
designed	O
to	O
fit	O
in	O
the	O
same	O
space	O
as	O
an	O
IBM	O
Selectric	O
typewriter	O
and	O
used	O
a	O
video	O
screen	O
shaped	O
to	O
have	O
the	O
same	O
aspect	B-Device
ratio	I-Device
as	O
an	O
IBM	O
punched	B-Architecture
card	I-Architecture
.	O
</s>
<s>
Another	O
major	O
concern	O
was	O
that	O
Intel	O
's	O
existing	O
customer	O
base	O
purchased	O
their	O
memory	O
chips	O
for	O
use	O
with	O
their	O
own	O
processor	O
designs	O
;	O
if	O
Intel	O
introduced	O
their	O
own	O
processor	O
,	O
they	O
might	O
be	O
seen	O
as	O
a	O
competitor	O
,	O
and	O
their	O
customers	O
might	O
look	O
elsewhere	O
for	O
memory	O
.	O
</s>
<s>
Intel	O
's	O
own	O
versions	O
were	O
delayed	O
.	O
</s>
<s>
CTC	O
decided	O
to	O
re-implement	O
the	O
new	O
version	O
of	O
the	O
terminal	O
using	O
discrete	O
TTL	B-General_Concept
instead	O
of	O
waiting	O
for	O
a	O
single-chip	O
CPU	O
.	O
</s>
<s>
The	O
new	O
system	O
was	O
released	O
as	O
the	O
Datapoint	B-Device
2200	I-Device
in	O
the	O
spring	O
1970	O
,	O
with	O
their	O
first	O
sale	O
to	O
General	O
Mills	O
on	O
May	O
25	O
,	O
1970	O
.	O
</s>
<s>
Six	O
months	O
later	O
,	O
Seiko	O
approached	O
Intel	O
,	O
expressing	O
an	O
interest	O
in	O
using	O
the	O
1201	O
in	O
a	O
scientific	O
calculator	B-Application
,	O
likely	O
after	O
seeing	O
the	O
success	O
of	O
the	O
simpler	O
Intel	B-General_Concept
4004	I-General_Concept
used	O
by	O
Busicom	O
in	O
their	O
business	O
calculators	B-Application
.	O
</s>
<s>
A	O
small	O
re-design	O
followed	O
,	O
under	O
the	O
leadership	O
of	O
Federico	O
Faggin	O
,	O
the	O
designer	O
of	O
the	O
4004	B-General_Concept
,	O
now	O
project	O
leader	O
of	O
the	O
1201	O
,	O
expanding	O
from	O
a	O
16-pin	O
to	O
18-pin	O
design	O
,	O
and	O
the	O
new	O
1201	O
was	O
delivered	O
to	O
CTC	O
in	O
late	O
1971	O
.	O
</s>
<s>
By	O
that	O
point	O
,	O
CTC	O
had	O
once	O
again	O
moved	O
on	O
,	O
this	O
time	O
to	O
the	O
Datapoint	B-Device
2200	I-Device
II	O
,	O
which	O
was	O
faster	O
.	O
</s>
<s>
CTC	O
voted	O
to	O
end	O
their	O
involvement	O
with	O
the	O
1201	O
,	O
leaving	O
the	O
design	O
's	O
intellectual	O
property	O
to	O
Intel	O
instead	O
of	O
paying	O
the	O
$	O
50,000	O
contract	O
.	O
</s>
<s>
This	O
renaming	O
tried	O
to	O
ride	O
off	O
the	O
success	O
of	O
the	O
4004	B-General_Concept
chip	O
,	O
by	O
presenting	O
the	O
8008	O
as	O
simply	O
a	O
4	O
to	O
8	O
port	O
,	O
but	O
the	O
8008	O
is	O
not	O
based	O
on	O
the	O
4004	B-General_Concept
.	O
</s>
<s>
This	O
was	O
followed	O
by	O
the	O
Intel	B-General_Concept
8080	I-General_Concept
,	O
and	O
then	O
the	O
hugely	O
successful	O
Intel	B-Operating_System
x86	I-Operating_System
family	O
.	O
</s>
<s>
The	O
Sac	O
State	O
8008	O
was	O
possibly	O
the	O
first	O
true	O
microcomputer	O
,	O
with	O
a	O
disk	O
operating	O
system	O
built	O
with	O
IBM	B-Device
Basic	I-Device
assembly	I-Device
language	I-Device
in	O
PROM	O
,	O
all	O
driving	O
a	O
color	O
display	O
,	O
hard	O
drive	O
,	O
keyboard	O
,	O
modem	O
,	O
audio/paper	O
tape	O
reader	O
and	O
printer	O
.	O
</s>
<s>
Bill	O
assisted	O
Intel	O
with	O
the	O
MCS-8	O
kit	O
and	O
provided	O
key	O
input	O
to	O
the	O
Intel	B-General_Concept
8080	I-General_Concept
instruction	O
set	O
,	O
which	O
helped	O
make	O
it	O
useful	O
for	O
the	O
industry	O
and	O
hobbyists	O
.	O
</s>
<s>
In	O
the	O
UK	O
,	O
a	O
team	O
at	O
S	B-Algorithm
.	O
E	O
.	O
Laboratories	O
Engineering	O
(	O
EMI	O
)	O
led	O
by	O
Tom	O
Spink	O
in	O
1972	O
built	O
a	O
microcomputer	O
based	O
on	O
a	O
pre-release	O
sample	O
of	O
the	O
8008	O
.	O
</s>
<s>
The	O
operating	O
system	O
was	O
written	O
using	O
a	O
meta-assembler	B-Language
developed	O
by	O
L	O
.	O
Crawford	O
and	O
J	O
.	O
Parnell	O
for	O
a	O
Digital	O
Equipment	O
Corporation	O
PDP-11	B-Device
.	O
</s>
<s>
The	O
8008	O
was	O
the	O
CPU	O
for	O
the	O
very	O
first	O
commercial	O
non-calculator	O
personal	B-Device
computers	I-Device
(	O
excluding	O
the	O
Datapoint	B-Device
2200	I-Device
itself	O
)	O
:	O
the	O
US	O
SCELBI	B-Device
kit	O
and	O
the	O
pre-built	O
French	O
Micral	B-Device
N	I-Device
and	O
Canadian	O
MCM/70	B-Device
.	O
</s>
<s>
It	O
was	O
also	O
the	O
controlling	O
microprocessor	B-Architecture
for	O
the	O
first	O
several	O
models	O
in	O
Hewlett-Packard	O
'	O
s	B-Algorithm
2640	B-General_Concept
family	O
of	O
computer	B-General_Concept
terminals	I-General_Concept
.	O
</s>
<s>
Intel	O
offered	O
an	O
instruction	B-Application
set	I-Application
simulator	I-Application
for	O
the	O
8008	O
named	O
INTERP/8	O
.	O
</s>
<s>
It	O
was	O
written	O
in	O
FORTRAN	B-Application
.	O
</s>
<s>
The	O
8008	O
was	O
implemented	O
in	O
10μm	O
silicon-gate	O
enhancement-mode	O
PMOS	B-Algorithm
logic	I-Algorithm
.	O
</s>
<s>
Register	O
–	O
register	O
loads	O
and	O
ALU	O
operations	O
take	O
5T	O
(	O
20μs	O
at	O
0.5MHz	O
)	O
,	O
register	O
–	O
memory	O
8T	O
(	O
32μs	O
)	O
,	O
while	O
calls	O
and	O
jumps	O
(	O
when	O
taken	O
)	O
take	O
11	O
T-states	O
(	O
44μs	O
)	O
.	O
</s>
<s>
The	O
8008	O
is	O
a	O
little	O
slower	O
in	O
terms	O
of	O
instructions	O
per	O
second	O
(	O
36,000	O
to	O
80,000	O
at	O
0.8MHz	O
)	O
than	O
the	O
4-bit	O
Intel	B-General_Concept
4004	I-General_Concept
and	O
Intel	B-General_Concept
4040	I-General_Concept
.	O
but	O
since	O
the	O
8008	O
processes	O
data	O
8	O
bits	O
at	O
a	O
time	O
and	O
can	O
access	O
significantly	O
more	O
RAM	O
,	O
in	O
most	O
applications	O
it	O
has	O
a	O
significant	O
speed	O
advantage	O
over	O
these	O
processors	O
.	O
</s>
<s>
The	O
8008	O
has	O
3,500	O
transistors	B-Application
.	O
</s>
<s>
The	O
chip	O
(	O
limited	O
by	O
its	O
18-pin	O
DIP	B-Algorithm
)	O
has	O
a	O
single	O
8-bit	O
bus	O
and	O
requires	O
a	O
significant	O
amount	O
of	O
external	O
support	O
logic	O
.	O
</s>
<s>
For	O
controller	O
and	O
CRT	B-General_Concept
terminal	I-General_Concept
use	O
,	O
this	O
is	O
an	O
acceptable	O
design	O
,	O
but	O
it	O
is	O
rather	O
cumbersome	O
to	O
use	O
for	O
most	O
other	O
tasks	O
,	O
at	O
least	O
compared	O
to	O
the	O
next	O
generations	O
of	O
microprocessors	B-Architecture
.	O
</s>
<s>
A	O
few	O
early	O
computer	O
designs	O
were	O
based	O
on	O
it	O
,	O
but	O
most	O
would	O
use	O
the	O
later	O
and	O
greatly	O
improved	O
Intel	B-General_Concept
8080	I-General_Concept
instead	O
.	O
</s>
<s>
The	O
subsequent	O
40-pin	O
NMOS	B-Algorithm
Intel	B-General_Concept
8080	I-General_Concept
expanded	O
upon	O
the	O
8008	O
registers	O
and	O
instruction	O
set	O
and	O
implements	O
a	O
more	O
efficient	O
external	O
bus	O
interface	O
(	O
using	O
the	O
22	O
additional	O
pins	O
)	O
.	O
</s>
<s>
Despite	O
a	O
close	O
architectural	O
relationship	O
,	O
the	O
8080	B-General_Concept
was	O
not	O
made	O
binary	O
compatible	O
with	O
the	O
8008	O
,	O
so	O
an	O
8008	O
program	O
would	O
not	O
run	O
on	O
an	O
8080	B-General_Concept
.	O
</s>
<s>
However	O
,	O
as	O
two	O
different	O
assembly	B-Language
syntaxes	O
were	O
used	O
by	O
Intel	O
at	O
the	O
time	O
,	O
the	O
8080	B-General_Concept
could	O
be	O
used	O
in	O
an	O
8008	O
assembly-language	O
backward-compatible	O
fashion	O
.	O
</s>
<s>
The	O
Intel	B-General_Concept
8085	I-General_Concept
is	O
an	O
electrically	O
modernized	O
version	O
of	O
the	O
8080	B-General_Concept
that	O
uses	O
depletion-mode	B-Algorithm
transistors	B-Application
and	O
also	O
added	O
two	O
new	O
instructions	O
.	O
</s>
<s>
The	O
Intel	B-General_Concept
8086	I-General_Concept
,	O
the	O
original	O
x86	B-Operating_System
processor	O
,	O
is	O
a	O
non-strict	O
extension	O
of	O
the	O
8080	B-General_Concept
,	O
so	O
it	O
loosely	O
resembles	O
the	O
original	O
Datapoint	B-Device
2200	I-Device
design	O
as	O
well	O
.	O
</s>
<s>
Almost	O
every	O
Datapoint	B-Device
2200	I-Device
and	O
8008	O
instruction	O
has	O
an	O
equivalent	O
not	O
only	O
in	O
the	O
instruction	O
set	O
of	O
the	O
8080	B-General_Concept
,	O
8085	B-General_Concept
,	O
and	O
Z80	B-General_Concept
,	O
but	O
also	O
in	O
the	O
instruction	O
set	O
of	O
modern	O
x86	B-Operating_System
processors	O
(	O
although	O
the	O
instruction	O
encodings	O
are	O
different	O
)	O
.	O
</s>
<s>
Seven	O
8-bit	O
"	O
scratchpad	O
"	O
registers	O
:	O
The	O
main	O
accumulator	O
(	O
A	O
)	O
and	O
six	O
other	O
registers	O
(	O
B	O
,	O
C	B-Algorithm
,	O
D	O
,	O
E	O
,	O
H	O
,	O
and	O
L	O
)	O
.	O
</s>
<s>
Seven-level	O
push-down	O
address	O
call	B-General_Concept
stack	I-General_Concept
.	O
</s>
<s>
Four	O
condition	O
code	O
status	O
flags	O
:	O
carry	O
(	O
C	B-Algorithm
)	O
,	O
even	O
parity	O
(	O
P	B-General_Concept
)	O
,	O
zero	O
(	O
Z	B-Algorithm
)	O
,	O
and	O
sign	O
(	O
S	B-Algorithm
)	O
.	O
</s>
<s>
The	O
following	O
8008	O
assembly	B-Language
source	O
code	O
is	O
for	O
a	O
subroutine	O
named	O
MEMCPY	O
that	O
copies	O
a	O
block	O
of	O
data	O
bytes	O
of	O
a	O
given	O
size	O
from	O
one	O
location	O
to	O
another	O
.	O
</s>
<s>
The	O
8008	O
(	O
originally	O
called	O
1201	O
)	O
chip	O
design	O
started	O
before	O
the	O
4004	B-General_Concept
development	O
.	O
</s>
<s>
Hoff	O
and	O
Mazor	O
,	O
however	O
,	O
could	O
not	O
and	O
did	O
not	O
develop	O
a	O
"	O
silicon	O
design	O
"	O
because	O
they	O
were	O
neither	O
chip	O
designers	O
nor	O
process	O
developers	O
,	O
and	O
furthermore	O
the	O
necessary	O
silicon-gate-based	O
design	O
methodology	O
and	O
circuits	O
,	O
under	O
development	O
by	O
Federico	O
Faggin	O
for	O
the	O
4004	B-General_Concept
,	O
were	O
not	O
yet	O
available	O
.	O
</s>
<s>
Federico	O
Faggin	O
,	O
having	O
finished	O
the	O
design	O
of	O
the	O
4004	B-General_Concept
,	O
became	O
leader	O
of	O
the	O
project	O
from	O
January	O
1971	O
until	O
its	O
successful	O
completion	O
in	O
April	O
1972	O
,	O
after	O
it	O
had	O
been	O
suspended	O
–	O
for	O
lack	O
of	O
progress	O
–	O
for	O
about	O
seven	O
months	O
.	O
</s>
<s>
Hal	O
Feeney	O
,	O
project	O
engineer	O
,	O
did	O
the	O
detailed	O
logic	O
design	O
,	O
circuit	O
design	O
,	O
and	O
physical	O
layout	O
under	O
Faggin	O
's	O
supervision	O
,	O
employing	O
the	O
same	O
design	O
methodology	O
that	O
Faggin	O
had	O
originally	O
developed	O
for	O
the	O
Intel	B-General_Concept
4004	I-General_Concept
microprocessor	B-Architecture
,	O
and	O
utilizing	O
the	O
basic	O
circuits	O
he	O
had	O
developed	O
for	O
the	O
4004	B-General_Concept
.	O
</s>
