<s>
The	O
IBM	O
PC	O
Convertible	O
(	O
model	O
5140	O
)	O
is	O
a	O
laptop	B-Device
computer	I-Device
made	O
by	O
IBM	O
,	O
first	O
sold	O
in	O
April	O
1986	O
.	O
</s>
<s>
The	O
Convertible	O
was	O
IBM	O
's	O
first	O
laptop-style	O
computer	O
,	O
following	O
the	O
luggable	O
IBM	B-Device
Portable	I-Device
,	O
and	O
introduced	O
the	O
3½-inch	O
floppy	B-Device
disk	I-Device
format	O
to	O
the	O
IBM	O
product	O
line	O
.	O
</s>
<s>
Like	O
modern	O
laptops	B-Device
,	O
it	O
featured	O
power	O
management	O
and	O
the	O
ability	O
to	O
run	O
from	O
batteries	O
.	O
</s>
<s>
It	O
was	O
replaced	O
in	O
1991	O
by	O
the	O
IBM	B-Device
PS/2	I-Device
L40	I-Device
SX	I-Device
,	O
and	O
in	O
Japan	O
by	O
the	O
IBM	B-Device
Personal	I-Device
System/55note	I-Device
,	O
the	O
predecessor	O
to	O
the	O
ThinkPad	B-Operating_System
.	O
</s>
<s>
IBM	O
had	O
been	O
working	O
on	O
a	O
laptop	B-Device
for	O
some	O
time	O
before	O
the	O
Convertible	O
.	O
</s>
<s>
In	O
1983	O
,	O
work	O
was	O
underway	O
on	O
a	O
laptop	B-Device
similar	O
to	O
the	O
Tandy	B-Operating_System
Model	I-Operating_System
100	I-Operating_System
,	O
codenamed	O
"	O
Sweetpea	O
,	O
"	O
but	O
it	O
was	O
rejected	O
by	O
Don	O
Estridge	O
for	O
not	O
being	O
PC	O
compatible	O
.	O
</s>
<s>
Another	O
attempt	O
in	O
1984	O
produced	O
the	O
"	O
P-14	O
"	O
prototype	O
machine	O
,	O
but	O
it	O
failed	O
to	O
pass	O
IBM	O
's	O
human	O
factors	O
tests	O
,	O
especially	O
after	O
poor	O
public	O
reception	O
of	O
the	O
display	O
in	O
the	O
competing	O
Data	B-Device
General-One	I-Device
.	O
</s>
<s>
The	O
latter	O
two	O
were	O
released	O
in	O
October	O
1987	O
and	O
are	O
primarily	O
distinguished	O
by	O
their	O
LCD	B-Device
panels	I-Device
.	O
</s>
<s>
The	O
Model	O
2	O
lacked	O
a	O
backlight	O
as	O
well	O
but	O
upgraded	O
to	O
an	O
improved	O
supertwist	B-General_Concept
panel	O
,	O
and	O
the	O
Model	O
3	O
included	O
a	O
backlight	O
.	O
</s>
<s>
The	O
CPU	B-General_Concept
is	O
an	O
Intel	B-Device
80C88	I-Device
,	O
the	O
CMOS	B-Device
version	O
of	O
the	O
Intel	B-Device
8088	I-Device
CPU	B-General_Concept
.	O
</s>
<s>
The	O
base	O
configuration	O
included	O
of	O
RAM	O
,	O
expandable	O
to	O
,	O
dual	O
3.5-inch	O
floppy	B-Device
drives	I-Device
,	O
and	O
a	O
monochrome	O
,	O
CGA-compatible	O
LCD	B-Device
screen	I-Device
.	O
</s>
<s>
The	O
LCD	B-Device
screen	I-Device
displayed	O
characters	O
,	O
but	O
has	O
a	O
very	O
wide	O
aspect	O
ratio	O
,	O
so	O
text	O
characters	O
and	O
graphics	O
are	O
compressed	O
vertically	O
,	O
appearing	O
half	O
their	O
normal	O
height	O
.	O
</s>
<s>
The	O
PC	O
Convertible	O
has	O
expansion	O
capabilities	O
through	O
a	O
proprietary	O
ISA-based	O
port	O
on	O
the	O
rear	O
of	O
the	O
machine	O
.	O
</s>
<s>
The	O
machine	O
can	O
also	O
take	O
an	O
internal	O
modem	B-Application
,	O
but	O
has	O
no	O
room	O
for	O
an	O
internal	O
hard	B-Device
disk	I-Device
.	O
</s>
<s>
The	O
CMOS	B-Device
80C88	B-Device
CPU	B-General_Concept
has	O
a	O
static	B-General_Concept
core	I-General_Concept
,	O
which	O
holds	O
its	O
state	O
indefinitely	O
by	O
stopping	O
the	O
system	O
clock	O
oscillator	O
,	O
and	O
can	O
resume	O
processing	O
when	O
the	O
clock	O
signal	O
is	O
restarted	O
as	O
long	O
as	O
it	O
is	O
kept	O
powered	O
.	O
</s>
<s>
The	O
system	O
RAM	O
in	O
the	O
Convertible	O
is	O
SRAM	O
rather	O
than	O
DRAM	O
,	O
both	O
for	O
lower	O
power	O
consumption	O
and	O
less	O
circuitry	O
to	O
fit	O
into	O
the	O
cramped	O
laptop	B-General_Concept
case	I-General_Concept
.	O
</s>
<s>
Pressing	O
a	O
lever	O
between	O
the	O
two	O
floppy	B-Device
drives	I-Device
just	O
below	O
the	O
display	O
detaches	O
the	O
entire	O
screen	O
from	O
the	O
unit	O
.	O
</s>
<s>
This	O
feature	O
allows	O
the	O
use	O
of	O
a	O
full-size	O
desktop	O
monitor	O
while	O
at	O
one	O
's	O
desk	O
,	O
an	O
early	O
forerunner	O
of	O
the	O
"	O
docking	O
station	O
"	O
concept	O
,	O
and	O
similar	O
to	O
Apple	O
's	O
PowerBook	B-Device
Duo	I-Device
.	O
</s>
<s>
The	O
machine	O
had	O
difficulty	O
in	O
the	O
marketplace	O
and	O
was	O
seen	O
as	O
a	O
poor	O
value	O
for	O
money	O
,	O
since	O
other	O
laptops	B-Device
in	O
the	O
market	O
had	O
more	O
built-in	O
features	O
,	O
although	O
it	O
enjoyed	O
some	O
success	O
with	O
business	O
users	O
,	O
who	O
saw	O
its	O
battery	O
life	O
and	O
portability	O
as	O
selling	O
points	O
.	O
</s>
<s>
The	O
Convertible	O
was	O
heavy	O
,	O
not	O
much	O
faster	O
than	O
the	O
Portable	O
it	O
replaced	O
,	O
had	O
no	O
traditional	O
PC	O
expansion	O
ports	O
(	O
such	O
as	O
serial	B-Protocol
ports	I-Protocol
and	O
a	O
parallel	B-Device
port	I-Device
)	O
without	O
an	O
add-on	O
,	O
and	O
had	O
a	O
hard-to-read	O
,	O
oddly-shaped	O
LCD	B-Device
screen	I-Device
.	O
</s>
<s>
It	O
also	O
competed	O
against	O
faster	O
portables	O
based	O
on	O
the	O
Intel	B-General_Concept
80286	I-General_Concept
that	O
offered	O
optional	O
hard	B-Device
drives	I-Device
,	O
from	O
companies	O
such	O
as	O
Compaq	O
,	O
and	O
laptops	B-Device
from	O
companies	O
such	O
as	O
Toshiba	O
and	O
Zenith	O
that	O
were	O
lighter	O
and	O
offered	O
similar	O
specifications	O
,	O
sometimes	O
at	O
half	O
the	O
price	O
.	O
</s>
