<s>
The	O
NEC	O
μCOM	O
series	O
is	O
a	O
series	O
of	O
microprocessors	B-Architecture
and	O
microcontrollers	B-Architecture
manufactured	O
by	O
NEC	O
in	O
the	O
1970s	O
and	O
1980s	O
.	O
</s>
<s>
The	O
initial	O
entries	O
in	O
the	O
series	O
were	O
custom-designed	O
4	O
and	O
16-bit	O
designs	O
,	O
but	O
later	O
models	O
in	O
the	O
series	O
were	O
mostly	O
based	O
on	O
the	O
Intel	B-General_Concept
8080	I-General_Concept
and	O
Zilog	B-General_Concept
Z80	I-General_Concept
8-bit	O
designs	O
,	O
and	O
later	O
,	O
the	O
Intel	B-General_Concept
8086	I-General_Concept
16-bit	O
design	O
.	O
</s>
<s>
Most	O
of	O
the	O
line	O
was	O
replaced	O
in	O
1984	O
by	O
the	O
NEC	B-Device
V20	I-Device
,	O
an	O
Intel	B-Device
8088	I-Device
clone	O
.	O
</s>
<s>
The	O
μCOM	O
series	O
has	O
its	O
roots	O
in	O
one	O
of	O
the	O
world	O
's	O
earliest	O
microprocessor	B-Architecture
chipsets	O
,	O
the	O
two-chip	O
processor	O
µPD707	O
/	O
µPD708	O
.	O
</s>
<s>
The	O
chipset	O
development	O
was	O
complete	O
in	O
December	O
1971	O
,	O
at	O
about	O
the	O
same	O
time	O
as	O
other	O
early	O
microprocessors	B-Architecture
in	O
the	O
USA	O
.	O
</s>
<s>
Since	O
then	O
,	O
NEC	O
has	O
developed	O
and	O
manufactured	O
various	O
microprocessors	B-Architecture
and	O
microcontrollers	B-Architecture
.	O
</s>
<s>
The	O
μCOM-4	B-Device
series	O
(	O
4	O
bit	O
)	O
and	O
μCOM-16	O
series	O
(	O
16	O
bit	O
)	O
were	O
original	O
developments	O
,	O
while	O
the	O
μCOM-8	O
series	O
(	O
8	O
bit	O
and	O
16	O
bit	O
)	O
consisted	O
mostly	O
of	O
Intel	O
-	O
and	O
Zilog-compatible	O
microprocessors	B-Architecture
.	O
</s>
<s>
The	O
μCOM	O
name	O
disappeared	O
when	O
the	O
V	B-Device
series	I-Device
and	O
78K	B-Device
series	I-Device
appeared	O
in	O
the	O
1980s	O
,	O
and	O
the	O
μCOM-87AD	O
series	O
,	O
for	O
example	O
,	O
came	O
to	O
be	O
described	O
simply	O
as	O
the	O
87AD	O
series	O
.	O
</s>
<s>
The	O
μCOM-4	B-Device
( μPD751	O
)	O
is	O
NEC	O
's	O
original	O
single-chip	O
4-bit	O
microprocessor	B-Architecture
,	O
announced	O
in	O
1973	O
.	O
</s>
<s>
The	O
μCOM-41	O
( μPD541	O
)	O
is	O
a	O
PMOS	B-Algorithm
microprocessor	B-Architecture
in	O
a	O
42-pin	O
package	O
.	O
</s>
<s>
The	O
μCOM-42	O
( μPD548	O
)	O
is	O
a	O
4-bit	O
PMOS	B-Algorithm
microcontroller	B-Architecture
in	O
a	O
42-pin	O
package	O
.	O
</s>
<s>
The	O
μCOM-43	O
series	O
consists	O
of	O
more	O
than	O
10	O
different	O
4-bit	O
microcontrollers	B-Architecture
.	O
</s>
<s>
Broadly	O
speaking	O
,	O
there	O
are	O
PMOS	B-Algorithm
devices	O
( μPD500	O
series	O
)	O
,	O
NMOS	B-Algorithm
devices	O
( μPD1500	O
series	O
,	O
μCOM-43N	O
)	O
,	O
and	O
CMOS	B-Device
devices	O
( μPD650	O
series	O
,	O
μCOM-43C	O
)	O
.	O
</s>
<s>
The	O
μCOM-47	O
( μPD766	O
)	O
is	O
a	O
4-bit	O
NMOS	B-Algorithm
microcontroller	B-Architecture
in	O
a	O
64-pin	O
package	O
.	O
</s>
<s>
The	O
μCOM-75	O
series	O
consists	O
of	O
4-bit	O
microcontrollers	B-Architecture
.	O
</s>
<s>
Only	O
the	O
first	O
device	O
in	O
the	O
series	O
,	O
the	O
μPD7520	O
,	O
was	O
still	O
developed	O
in	O
PMOS	B-Algorithm
technology	O
.	O
</s>
<s>
All	O
subsequent	O
microcontrollers	B-Architecture
in	O
the	O
series	O
( μPD7502	O
etc	O
.	O
)	O
</s>
<s>
used	O
CMOS	B-Device
.	O
</s>
<s>
The	O
μCOM-8	O
( μPD753	O
)	O
is	O
an	O
8-bit	O
microprocessor	B-Architecture
that	O
is	O
software-compatible	O
with	O
the	O
Intel	B-General_Concept
8080	I-General_Concept
,	O
but	O
differs	O
in	O
its	O
42-pin	O
package	O
and	O
its	O
completely	O
different	O
pin-out	O
.	O
</s>
<s>
The	O
μCOM-80	O
( μPD8080A	O
)	O
is	O
an	O
8-bit	O
microprocessor	B-Architecture
that	O
is	O
pin-compatible	O
with	O
the	O
Intel	B-General_Concept
8080	I-General_Concept
and	O
software-compatible	O
with	O
the	O
μCOM-8	O
.	O
</s>
<s>
That	O
is	O
,	O
the	O
μPD8080A	O
has	O
some	O
improvements	O
compared	O
to	O
the	O
Intel	B-General_Concept
8080	I-General_Concept
:	O
</s>
<s>
BCD	O
arithmetic	O
is	O
supported	O
for	O
both	O
addition	O
and	O
subtraction	O
(	O
Intel	B-General_Concept
8080	I-General_Concept
:	O
addition	O
only	O
)	O
.	O
</s>
<s>
Similar	O
to	O
the	O
N	O
flag	O
in	O
the	O
Zilog	B-General_Concept
Z80	I-General_Concept
,	O
the	O
μPD8080A	O
has	O
a	O
SUB	O
flag	O
(	O
bit	O
5	O
of	O
the	O
flag	O
register	O
)	O
to	O
indicate	O
that	O
a	O
subtraction	O
was	O
performed	O
.	O
</s>
<s>
The	O
instruction	O
requires	O
4	O
clock	O
cycles	O
(	O
Intel	B-General_Concept
8080	I-General_Concept
:	O
5	O
clock	O
cycles	O
)	O
.	O
</s>
<s>
3-byte	O
instructions	O
are	O
allowed	O
in	O
an	O
interrupt	O
acknowledge	O
cycle	O
,	O
so	O
a	O
instruction	O
to	O
any	O
memory	O
address	O
can	O
be	O
used	O
(	O
Intel	B-General_Concept
8080	I-General_Concept
:	O
only	O
1-byte	O
instructions	O
are	O
allowed	O
)	O
.	O
</s>
<s>
Unfortunately	O
,	O
these	O
improvements	O
cause	O
some	O
programs	O
written	O
for	O
the	O
Intel	B-General_Concept
8080	I-General_Concept
not	O
to	O
run	O
correctly	O
.	O
</s>
<s>
To	O
overcome	O
this	O
problem	O
,	O
NEC	O
introduced	O
the	O
μCOM-80F	O
( μPD8080AF	O
)	O
which	O
is	O
completely	O
compatible	O
with	O
the	O
Intel	B-General_Concept
8080	I-General_Concept
in	O
all	O
details	O
.	O
</s>
<s>
With	O
the	O
TK-80	B-Device
,	O
NEC	O
offered	O
a	O
development	O
board	O
for	O
μCOM-80	O
,	O
which	O
due	O
to	O
its	O
low	O
price	O
became	O
popular	O
with	O
hobbyists	O
.	O
</s>
<s>
The	O
μCOM-82	O
( μPD780	O
)	O
is	O
an	O
8-bit	O
microprocessor	B-Architecture
compatible	O
with	O
the	O
Zilog	B-General_Concept
Z80	I-General_Concept
.	O
</s>
<s>
The	O
μPD780C	O
corresponds	O
to	O
the	O
original	O
Z80	B-General_Concept
(	O
max	O
.	O
</s>
<s>
2.5MHz	O
clock	O
)	O
,	O
while	O
the	O
μPD780C-1	O
corresponds	O
to	O
the	O
Z80A	B-General_Concept
(	O
max	O
.	O
</s>
<s>
4MHz	O
clock	O
)	O
and	O
the	O
μPD780C-2	O
to	O
the	O
Z80B	B-General_Concept
(	O
max	O
.	O
</s>
<s>
The	O
µPD780C-1	O
was	O
used	O
in	O
Sinclair	O
's	O
ZX80	B-Operating_System
,	O
ZX81	O
and	O
early	O
versions	O
of	O
the	O
ZX	B-Operating_System
Spectrum	I-Operating_System
,	O
in	O
several	O
MSX	B-Operating_System
and	O
NEC	O
(	O
PC-6000	B-Device
,	O
PC-8000	B-Device
,	O
PC-8800	B-Device
)	O
computers	O
,	O
in	O
musical	O
synthesizers	O
such	O
as	O
Oberheim	O
OB-8	O
,	O
and	O
in	O
Sega	O
's	O
SG-1000	B-Operating_System
game	O
console	O
.	O
</s>
<s>
A	O
CMOS	B-Device
version	O
( μPD70008	O
)	O
followed	O
later	O
.	O
</s>
<s>
is	O
compatible	O
with	O
Intel	O
's	O
8-bit	O
microcontroller	B-Architecture
8048	B-Device
.	O
</s>
<s>
CMOS	B-Device
microcontrollers	B-Architecture
up	O
to	O
μPD80C50	O
followed	O
,	O
but	O
an	O
Intel	B-Architecture
8051	I-Architecture
compatible	O
product	O
,	O
which	O
is	O
the	O
8-bit	O
industry	O
standard	O
,	O
was	O
never	O
offered	O
.	O
</s>
<s>
The	O
µCOM-85	O
( µPD8085	O
)	O
is	O
an	O
Intel	B-General_Concept
8085	I-General_Concept
compatible	O
8-bit	O
microprocessor	B-Architecture
.	O
</s>
<s>
The	O
µCOM-86	O
( µPD8086	O
)	O
and	O
µCOM-88	O
( µPD8088	O
)	O
are	O
Intel	B-General_Concept
8086	I-General_Concept
and	O
Intel	B-Device
8088	I-Device
compatible	O
16-bit	O
microprocessors	B-Architecture
.	O
</s>
<s>
They	O
were	O
superseded	O
by	O
the	O
V	B-Device
series	I-Device
.	O
</s>
<s>
are	O
NEC	O
original	O
8-bit	O
microcontrollers	B-Architecture
.	O
</s>
<s>
The	O
V	O
register	O
is	O
a	O
vector	O
register	O
that	O
stores	O
the	O
upper	O
8	O
bits	O
of	O
the	O
address	O
of	O
the	O
working	O
memory	O
area	O
,	O
and	O
the	O
short	O
address	O
space	O
which	O
is	O
fixed	O
in	O
the	O
current	O
78K	B-Device
series	I-Device
can	O
be	O
freely	O
arranged	O
.	O
</s>
<s>
In	O
the	O
µPD7807	O
and	O
later	O
,	O
the	O
ALU	B-General_Concept
is	O
expanded	O
to	O
16	O
bit	O
and	O
an	O
EA	O
register	O
is	O
added	O
for	O
16-bit	O
operation	O
.	O
</s>
<s>
The	O
series	O
came	O
in	O
64-pin	O
quad	B-Algorithm
in-line	I-Algorithm
package	I-Algorithm
.	O
</s>
<s>
This	O
series	O
was	O
superseded	O
by	O
the	O
78K	B-Device
series	I-Device
.	O
</s>
<s>
The	O
μCOM-16	O
is	O
a	O
NEC	O
original	O
16-bit	O
microprocessor	B-Architecture
,	O
implemented	O
in	O
two	O
chips	O
,	O
the	O
μPD755	O
(	O
register	O
+	O
ALU	B-General_Concept
)	O
and	O
μPD756	O
(	O
controller	O
)	O
,	O
in	O
1974	O
.	O
</s>
<s>
The	O
μCOM-1600	O
( μPD768	O
)	O
is	O
a	O
NEC	O
original	O
single-chip	O
16-bit	O
microprocessor	B-Architecture
that	O
was	O
announced	O
in	O
1978	O
.	O
</s>
