<s>
The	O
MK14	B-Device
(	O
Microcomputer	B-Device
Kit	I-Device
14	I-Device
)	O
was	O
a	O
computer	O
kit	O
sold	O
by	O
Science	O
of	O
Cambridge	O
of	O
the	O
United	O
Kingdom	O
,	O
first	O
introduced	O
in	O
1977	O
for	O
£39.95	O
.	O
</s>
<s>
In	O
1977	O
,	O
Ian	O
Williamson	O
approached	O
Clive	O
Sinclair	O
and	O
Chris	O
Curry	O
with	O
a	O
computer	O
design	O
based	O
around	O
the	O
National	B-Device
Semiconductor	I-Device
SC/MP	I-Device
processor	O
.	O
</s>
<s>
However	O
,	O
after	O
National	O
Semiconductor	O
had	O
been	O
contacted	O
regarding	O
a	O
bulk	O
purchase	O
of	O
the	O
SC/MP	B-Device
processor	O
Sinclair	O
and	O
Curry	O
decided	O
to	O
use	O
the	O
chip	O
manufacturer	O
's	O
own	O
design	O
.	O
</s>
<s>
This	O
design	O
used	O
all	O
National	O
Semiconductor	O
chips	O
and	O
the	O
company	O
allowed	O
the	O
use	O
of	O
its	O
designs	O
,	O
the	O
SC/MP	B-Device
Introkit	O
and	O
Keyboard	B-Device
Kit	O
,	O
for	O
free	O
.	O
</s>
<s>
The	O
computer	O
is	O
based	O
around	O
National	O
Semiconductor	O
's	O
SC/MP	B-Device
CPU	O
(	O
INS8060	B-Device
)	O
and	O
shipped	O
with	O
256	O
bytes	B-Application
of	O
random	B-Architecture
access	I-Architecture
memory	I-Architecture
(	O
RAM	B-Architecture
)	O
and	O
512	O
bytes	B-Application
of	O
read	B-Device
only	I-Device
memory	I-Device
(	O
ROM	B-Device
)	O
as	O
standard	O
.	O
</s>
<s>
It	O
used	O
an	O
eight	O
or	O
nine	O
red	O
light-emitting	O
diode	O
(	O
LED	O
)	O
seven	O
segment	B-Device
display	I-Device
,	O
there	O
was	O
also	O
optional	O
VDU	B-Device
supporting	O
32×16	O
text	O
or	O
64×64	O
graphics	O
.	O
</s>
<s>
Input	O
and	O
output	O
was	O
a	O
20-key	O
keyboard	B-Device
and	O
reset	O
switch	O
.	O
</s>
<s>
The	O
on-board	O
RAM	B-Architecture
could	O
be	O
increased	O
in	O
two	O
ways	O
;	O
by	O
the	O
addition	O
of	O
an	O
INS8154N	O
RAM/IO	O
chip	O
providing	O
an	O
additional	O
128	O
bytes	B-Application
of	O
RAM	B-Architecture
along	O
with	O
16I/O	O
lines	O
,	O
and	O
also	O
a	O
further	O
256	O
bytes	B-Application
by	O
adding	O
two	O
256	O
×	O
4	O
bit	O
RAM	B-Architecture
chips	I-Architecture
giving	O
a	O
maximum	O
of	O
640	O
bytes	B-Application
on	O
board	O
.	O
</s>
<s>
It	O
was	O
possible	O
to	O
connect	O
off-board	O
RAM	B-Architecture
giving	O
a	O
2170	O
bytes	B-Application
total	O
.	O
</s>
<s>
The	O
MK14	B-Device
could	O
address	O
up	O
to	O
64KB	O
of	O
memory	O
space	O
by	O
adding	O
a	O
few	O
chips	O
(	O
the	O
NADS	O
address	O
strobe	O
indicated	O
when	O
the	O
most	O
significant	O
four	O
bits	O
of	O
address	O
were	O
available	O
to	O
be	O
captured	O
by	O
an	O
external	O
latch	O
)	O
;	O
many	O
pioneering	O
homebrew	O
computer	O
magazines	O
such	O
as	O
Personal	O
Computer	O
World	O
,	O
and	O
Practical	O
Electronics	O
carried	O
details	O
of	O
user	O
modifications	O
.	O
</s>
