<s>
The	O
Sharp	B-Device
PC-4500	I-Device
is	O
a	O
line	O
of	O
laptop	B-Device
computers	I-Device
released	O
by	O
Sharp	O
Corporation	O
in	O
1987	O
.	O
</s>
<s>
The	O
PC-4501	O
is	O
a	O
bare-bones	O
unit	O
with	O
only	O
256KB	O
of	O
RAM	B-Architecture
stock	O
,	O
only	O
one	O
floppy	O
drive	O
,	O
no	O
backlighting	O
,	O
and	O
no	O
built-in	O
numeric	B-Device
keypad	I-Device
;	O
the	O
PC-4502	O
and	O
PC-4521	O
bumps	O
the	O
stock	O
RAM	B-Architecture
to	O
640KB	O
and	O
includes	O
the	O
latter	O
two	O
features	O
while	O
providing	O
either	O
two	O
floppy	O
drive	O
(	O
PC-4502	O
)	O
or	O
one	O
floppy	O
drive	O
and	O
a	O
20MB	O
hard	O
drive	O
(	O
PC-4521	O
)	O
.	O
</s>
<s>
Prices	O
on	O
the	O
line	O
initially	O
ranged	O
from	O
$	O
1,295	O
to	O
just	O
under	O
$	O
3,000	O
;	O
the	O
PC-4501	O
was	O
later	O
sold	O
for	O
$995	O
,	O
becoming	O
one	O
of	O
the	O
first	O
sub-	O
$	O
1,000	O
laptops	B-Device
available	O
on	O
the	O
market	O
.	O
</s>
<s>
The	O
computer	O
features	O
the	O
80188-compatible	O
NEC	B-Device
V40	I-Device
central	B-General_Concept
processing	I-General_Concept
unit	I-General_Concept
with	O
a	O
clock	O
speed	O
selectable	O
between	O
the	O
IBM	B-Device
PC	I-Device
standard	O
4.77MHz	O
and	O
7.16MHz	O
.	O
</s>
<s>
The	O
NEC	B-Device
V40	I-Device
,	O
with	O
its	O
16-bit	O
internal	O
data	O
bus	O
and	O
8-bit	O
external	O
data	O
bus	O
,	O
was	O
chosen	O
to	O
evade	O
a	O
contemporary	O
tariff	O
on	O
imported	O
laptops	B-Device
with	O
pure	O
16-bit	O
CPUs	O
.	O
</s>
<s>
Personal	O
computers	O
based	O
on	O
the	O
80188	B-Device
processor	O
and	O
its	O
derivatives	O
were	O
relatively	O
uncommon	O
.	O
</s>
<s>
The	O
most	O
inexpensive	O
entry	O
in	O
the	O
PC-4500	O
line	O
,	O
the	O
PC-4501	O
,	O
features	O
256	O
KB	O
of	O
RAM	B-Architecture
,	O
a	O
non-backlit	O
supertwisted	B-General_Concept
nematic	I-General_Concept
monochrome	O
LCD	B-Device
with	O
a	O
resolution	O
of	O
640	O
by	O
200	O
pixels	O
—	O
CGA	B-Device
compatible	O
—	O
a	O
78-key	O
keyboard	O
(	O
missing	O
a	O
numeric	B-Device
keypad	I-Device
)	O
,	O
and	O
one	O
3.5-inch	O
double-density	O
floppy	O
disk	O
drive	O
and	O
came	O
shipped	O
with	O
MS-DOS	O
2.11	O
.	O
</s>
<s>
The	O
middle-of-the-line	O
entry	O
,	O
the	O
PC-4502	O
,	O
features	O
640	O
KB	O
of	O
RAM	B-Architecture
,	O
a	O
backlit	O
display	O
of	O
the	O
same	O
specification	O
,	O
an	O
88-key	O
keyboard	O
(	O
numeric	B-Device
keypad	I-Device
)	O
,	O
two	O
3.5-inch	O
double-density	O
floppy	O
drives	O
and	O
came	O
shipped	O
with	O
MS-DOS	O
3.21	O
and	O
GW-BASIC	B-Language
3.2	O
.	O
</s>
<s>
All	O
entries	O
support	O
1.6	O
MB	O
of	O
RAM	B-Architecture
maximum	O
.	O
</s>
<s>
Two	O
proprietary	O
expansion	O
slots	O
may	O
hold	O
a	O
video	O
card	O
for	O
output	O
to	O
external	O
CGA	B-Device
monitors	O
,	O
a	O
RAM	B-Architecture
card	O
for	O
addition	O
addition	O
memory	O
(	O
accordant	O
to	O
the	O
Expanded	B-Device
Memory	I-Device
Specification	I-Device
)	O
,	O
an	O
EPROM	B-General_Concept
card	O
,	O
a	O
serial	B-Protocol
port	I-Protocol
card	O
,	O
and	O
a	O
1,200	O
-baud	O
modem	B-Application
card	O
.	O
</s>
<s>
The	O
EPROM	B-General_Concept
card	O
holds	O
multiple	O
EPROM	B-General_Concept
chips	O
,	O
up	O
to	O
768KB	O
in	O
total	O
,	O
onto	O
which	O
software	O
can	O
be	O
burned	O
for	O
instantaneous	O
loading	O
without	O
slowdown	O
from	O
floppy	O
or	O
hard	O
disk	O
drive	O
access	O
.	O
</s>
<s>
The	O
memory	O
card	O
,	O
the	O
EPROM	B-General_Concept
card	O
,	O
and	O
the	O
video	O
card	O
all	O
occupy	O
the	O
same	O
slot	O
and	O
cannot	O
be	O
used	O
in	O
tandem	O
.	O
</s>
<s>
The	O
serial	O
and	O
modem	B-Application
cards	O
also	O
occupy	O
the	O
same	O
slot	O
,	O
but	O
the	O
modem	B-Application
card	O
comes	O
with	O
a	O
serial	B-Protocol
port	I-Protocol
its	O
own	O
.	O
</s>
<s>
Sharp	O
announced	O
the	O
Sharp	B-Device
PC-4500	I-Device
line	O
at	O
COMDEX/Spring	O
1987	O
in	O
June	O
that	O
year	O
.	O
</s>
<s>
In	O
February	O
1988	O
,	O
Sharp	O
dropped	O
the	O
price	O
of	O
the	O
PC-4501	O
to	O
$995	O
,	O
becoming	O
one	O
of	O
the	O
first	O
manufacturers	O
of	O
sub-	O
$1000	O
PC-compatible	O
laptops	B-Device
.	O
</s>
<s>
Sharp	O
sold	O
an	O
estimated	O
26,000	O
units	O
of	O
PC-4500	O
laptops	B-Device
in	O
1988	O
by	O
November	O
that	O
year	O
.	O
</s>
<s>
Lamont	O
Wood	O
of	O
InfoWorld	O
rated	O
the	O
PC-4501	O
satisfactory	O
in	O
the	O
categories	O
of	O
performance	O
,	O
ease-of-use	O
,	O
serviceability	O
and	O
value	O
,	O
and	O
good	O
in	O
setting-up	O
,	O
but	O
wrote	O
that	O
its	O
basic	O
features	O
"	O
were	O
no	O
longer	O
enough	O
in	O
the	O
fast-moving	O
market	O
of	O
laptop	B-Device
computers	I-Device
"	O
,	O
with	O
the	O
stock	O
PC-4501	O
especially	O
suffering	O
from	O
the	O
lack	O
of	O
a	O
built-in	O
serial	B-Protocol
port	I-Protocol
.	O
</s>
<s>
Wood	O
rated	O
its	O
7.16-MHz	O
CPU	O
only	O
42	O
percent	O
faster	O
than	O
the	O
original	O
IBM	B-Device
PC	I-Device
's	O
4.77-MHz	O
8088	B-Device
,	O
which	O
he	O
deemed	O
underwhelming	O
.	O
</s>
<s>
Wood	O
rated	O
the	O
lead-acid	O
battery	O
average	O
and	O
appreciated	O
its	O
invulnerability	O
to	O
the	O
memory	B-Algorithm
effect	I-Algorithm
—	O
a	O
phenomenon	O
which	O
plagued	O
competing	O
laptops	B-Device
with	O
nickel	O
–	O
cadmium	O
batteries	O
.	O
</s>
<s>
Wood	O
concluded	O
that	O
the	O
PC-4501	O
'	O
s	O
low	O
price	O
"	O
just	O
balances	O
the	O
lack	O
of	O
a	O
backlighting	O
option	O
and	O
the	O
added	O
cost	O
of	O
the	O
serial	B-Protocol
port	I-Protocol
"	O
,	O
rating	O
the	O
computer	O
overall	O
"	O
a	O
satisfactory	O
value	O
"	O
.	O
</s>
<s>
Jon	O
Pepper	O
of	O
PC	O
Week	O
compared	O
the	O
PC-4501	O
to	O
Toshiba	O
's	O
T1100	B-Device
Plus	I-Device
in	O
aesthetic	O
and	O
form	O
factor	O
and	O
praised	O
the	O
layout	O
of	O
its	O
keyboard	O
while	O
noting	O
that	O
its	O
key	O
switches	O
provided	O
too	O
much	O
resistance	O
.	O
</s>
<s>
Howard	O
Blumenthal	O
of	O
the	O
Chicago	O
Sun-Times	O
meanwhile	O
called	O
its	O
display	O
"	O
better	O
than	O
those	O
on	O
other	O
laptops	B-Device
"	O
and	O
wrote	O
that	O
the	O
features	O
it	O
lacked	O
compared	O
to	O
other	O
offerings	O
at	O
the	O
time	O
were	O
not	O
necessary	O
for	O
most	O
road	O
warriors	O
and	O
that	O
its	O
low	O
cost	O
made	O
up	O
for	O
the	O
lack	O
of	O
those	O
features	O
.	O
</s>
<s>
Gus	O
Venditto	O
of	O
PC	O
Magazine	O
wrote	O
that	O
the	O
PC-4501	O
'	O
s	O
keyboard	O
was	O
"	O
up	O
their	O
with	O
the	O
best	O
of	O
them	O
"	O
,	O
with	O
its	O
key	O
feel	O
"	O
springier	O
"	O
than	O
and	O
layout	O
superior	O
to	O
that	O
of	O
IBM	O
's	O
PC	B-Device
Convertible	I-Device
.	O
</s>
<s>
She	O
called	O
the	O
V20	O
CPU	O
"	O
more	O
than	O
fast	O
enough	O
for	O
standard	O
applications	O
"	O
after	O
testing	O
it	O
against	O
XyWrite	B-Application
and	O
Lotus	B-Application
1-2-3	I-Application
and	O
praised	O
the	O
versatility	O
of	O
the	O
BIOS	O
setup	O
utility	O
.	O
</s>
<s>
Simone	O
wrote	O
that	O
the	O
PC-4521	O
'	O
s	O
LCD	B-Device
had	O
a	O
subpar	O
contrast	O
ratio	O
and	O
that	O
the	O
peak	O
brightness	O
of	O
the	O
backlight	O
failed	O
to	O
prevent	O
the	O
display	O
from	O
becoming	O
washed	O
out	O
in	O
direct	O
sunlight	O
.	O
</s>
<s>
She	O
called	O
the	O
laptop	B-Device
's	O
dimensional	O
depth	O
perhaps	O
"	O
a	O
little	O
to	O
deep	O
for	O
an	O
airline	O
tray	O
"	O
but	O
found	O
it	O
and	O
the	O
lower-cost	O
PC-4501	O
and	O
PC-4502	O
exceptionally	O
lightweight	O
.	O
</s>
<s>
Simone	O
found	O
the	O
laptop	B-Device
overall	O
very	O
price	O
competitive	O
but	O
with	O
compromises	O
to	O
comfort	O
.	O
</s>
<s>
InfoWorld	O
rated	O
the	O
PC-4521	O
a	O
good	O
value	O
,	O
with	O
Sherwin	O
Levinson	O
writing	O
that	O
the	O
laptop	B-Device
had	O
the	O
slowest	O
CPU	O
of	O
nine	O
laptops	B-Device
tested	O
but	O
featured	O
the	O
best	O
keyboard	O
of	O
those	O
nine	O
.	O
</s>
<s>
He	O
concluded	O
that	O
the	O
computer	O
in	O
its	O
stock	O
configuration	O
,	O
without	O
the	O
optional	O
serial	B-Protocol
port	I-Protocol
and	O
monitor	O
output	O
,	O
were	O
the	O
main	O
tradeoffs	O
to	O
its	O
low	O
cost	O
.	O
</s>
<s>
John	O
Diebold	O
of	O
PC	O
World	O
wrote	O
that	O
the	O
PC-4521	O
had	O
the	O
"	O
dubious	O
distinction	O
of	O
being	O
the	O
slowest	O
laptop	B-Device
"	O
in	O
their	O
benchmark	O
of	O
seven	O
laptops	B-Device
contemporary	O
to	O
it	O
but	O
that	O
also	O
it	O
was	O
"	O
the	O
cheapest	O
,	O
and	O
at	O
just	O
under	O
15	O
pounds	O
...	O
the	O
second	O
lightest	O
"	O
.	O
</s>
<s>
Diebold	O
called	O
the	O
display	O
"	O
small	O
but	O
readable	O
"	O
and	O
appreciated	O
the	O
computer	O
's	O
wake-on-ring	O
feature	O
of	O
its	O
modem	B-Application
firmware	O
but	O
found	O
the	O
PC-4521	O
'	O
s	O
power-savings	O
abilities	O
among	O
the	O
worst	O
of	O
the	O
magazine	O
's	O
roundup	O
.	O
</s>
<s>
He	O
wrote	O
that	O
the	O
LCD	B-Device
suffered	O
from	O
a	O
slow	O
refresh	O
rate	O
but	O
found	O
its	O
dark-blue-on-light-blue	O
color	O
scheme	O
"	O
easy	O
on	O
the	O
eyes	O
"	O
.	O
</s>
