<s>
Windows	B-Application
2.1	I-Application
is	O
a	O
major	O
release	O
of	O
Microsoft	B-Application
Windows	I-Application
.	O
</s>
<s>
It	O
was	O
released	O
to	O
manufacturing	O
on	O
May	O
27	O
,	O
1988	O
,	O
as	O
a	O
successor	O
to	O
Windows	B-Application
2.0	I-Application
.	O
</s>
<s>
It	O
was	O
released	O
with	O
two	O
different	O
variants	O
with	O
differing	O
CPU	B-Device
compatibility	O
,	O
also	O
known	O
as	O
Windows/286	O
and	O
Windows/386	O
,	O
so	O
the	O
versions	O
are	O
considered	O
to	O
be	O
similar	O
to	O
its	O
predecessor	O
.	O
</s>
<s>
In	O
comparison	O
,	O
the	O
Windows/386	O
variant	O
is	O
considered	O
to	O
be	O
better	O
than	O
the	O
286	B-General_Concept
one	O
,	O
since	O
it	O
provides	O
support	O
for	O
EMS	B-Device
emulation	I-Device
and	O
is	O
designed	O
to	O
use	O
both	O
conventional	O
and	O
extended	O
memory	O
.	O
</s>
<s>
Changes	O
to	O
the	O
user	B-Application
interface	I-Application
did	O
not	O
occur	O
in	O
this	O
version	O
,	O
and	O
rather	O
,	O
its	O
performance	O
was	O
increased	O
and	O
enhanced	O
memory	O
management	O
was	O
added	O
.	O
</s>
<s>
The	O
version	O
is	O
also	O
noted	O
to	O
be	O
the	O
first	O
one	O
to	O
require	O
a	O
hard	B-Device
disk	I-Device
drive	I-Device
.	O
</s>
<s>
Enhancements	O
that	O
were	O
introduced	O
were	O
considered	O
to	O
have	O
improved	O
the	O
operating	B-Application
environment	I-Application
,	O
while	O
the	O
Windows/386	O
variant	O
was	O
noted	O
to	O
have	O
a	O
good	O
level	O
of	O
functionality	O
.	O
</s>
<s>
It	O
was	O
considered	O
to	O
be	O
one	O
of	O
the	O
most	O
popular	O
80386-based	O
systems	O
.	O
</s>
<s>
The	O
sales	O
of	O
Microsoft	B-Application
Windows	I-Application
continued	O
to	O
go	O
up	O
after	O
its	O
release	O
,	O
and	O
in	O
May	O
1990	O
,	O
it	O
was	O
succeeded	O
by	O
Windows	B-Application
3.0	I-Application
,	O
which	O
is	O
considered	O
to	O
be	O
the	O
first	O
Windows	O
version	O
to	O
perform	O
well	O
both	O
critically	O
and	O
commercially	O
.	O
</s>
<s>
Like	O
its	O
predecessor	O
,	O
Windows	B-Application
2.0	I-Application
,	O
the	O
operating	B-Application
environment	I-Application
was	O
released	O
with	O
two	O
different	O
variants	O
with	O
differing	O
CPU	B-Device
compatibility	O
.	O
</s>
<s>
However	O
,	O
the	O
cosmetic	O
naming	O
convention	O
was	O
changed	O
to	O
"	O
Windows/286	O
"	O
and	O
"	O
Windows/386	O
"	O
.	O
</s>
<s>
It	O
was	O
released	O
on	O
May	O
27	O
,	O
1988	O
,	O
and	O
it	O
was	O
the	O
first	O
version	O
of	O
Windows	O
to	O
require	O
a	O
hard	B-Device
disk	I-Device
drive	I-Device
.	O
</s>
<s>
Despite	O
its	O
name	O
,	O
Windows/286	O
was	O
fully	O
operational	O
on	O
an	O
8088	B-Device
or	O
8086	B-General_Concept
processor	O
,	O
although	O
,	O
it	O
would	O
not	O
use	O
the	O
high	B-Device
memory	I-Device
area	I-Device
since	O
it	O
did	O
not	O
exist	O
on	O
an	O
8086	B-General_Concept
processor	O
.	O
</s>
<s>
It	O
is	O
a	O
rehash	O
of	O
its	O
predecessor	O
,	O
Windows	B-Application
2.03	I-Application
.	O
</s>
<s>
The	O
variant	O
uses	O
additional	O
64KB	O
of	O
the	O
extended	O
286	B-General_Concept
KB	O
memory	O
in	O
real	B-Application
mode	I-Application
.	O
</s>
<s>
A	O
few	O
PC	O
vendors	O
shipped	O
Windows/286	O
with	O
Intel	B-General_Concept
8086	I-General_Concept
hardware	O
;	O
one	O
such	O
example	O
was	O
IBM	O
's	O
PS/2	B-Device
Model	I-Device
25	I-Device
,	O
which	O
included	O
Windows/286	O
,	O
resulting	O
in	O
some	O
customer	O
confusion	O
.	O
</s>
<s>
The	O
other	O
variant	O
,	O
Windows/386	O
,	O
is	O
more	O
advanced	O
since	O
it	O
had	O
introduced	O
a	O
protected	B-Application
mode	I-Application
kernel	O
,	O
and	O
it	O
allows	O
several	O
MS-DOS	B-Application
programs	O
to	O
run	O
in	O
a	O
parallel	O
in	O
"	O
virtual	O
8086	B-General_Concept
"	O
CPU	B-Device
mode	O
,	O
rather	O
than	O
suspending	O
background	O
applications	O
.	O
</s>
<s>
It	O
has	O
also	O
provided	O
support	O
for	O
EMS	B-Device
emulation	I-Device
,	O
to	O
make	O
the	O
RAM	B-Architecture
beyond	O
the	O
640	O
KB	O
limit	O
.	O
</s>
<s>
It	O
has	O
spruced-up	O
rendering	O
of	O
the	O
80386	B-General_Concept
version	O
,	O
and	O
its	O
setup	O
program	O
is	O
considered	O
to	O
be	O
better	O
than	O
the	O
Windows/286	O
one	O
.	O
</s>
<s>
Windows/386	O
is	O
designed	O
to	O
use	O
both	O
conventional	O
and	O
extended	O
memory	O
,	O
although	O
it	O
ignores	O
expanded	B-Device
memory	I-Device
.	O
</s>
<s>
The	O
facilities	O
for	O
converting	O
extended	O
memory	O
into	O
expanded	B-Device
memory	I-Device
are	O
built	O
into	O
Windows/386	O
,	O
although	O
,	O
any	O
EMS	O
that	O
is	O
separately	O
controlled	O
would	O
not	O
be	O
available	O
on	O
Windows/386	O
.	O
</s>
<s>
To	O
customize	O
Windows/386	O
,	O
users	O
would	O
have	O
to	O
manually	O
change	O
the	O
CONFIG.SYS	B-Device
file	O
.	O
</s>
<s>
Microsoft	O
ended	O
its	O
support	O
for	O
Windows	B-Application
2.1	I-Application
on	O
December	O
31	O
,	O
2001	O
.	O
</s>
<s>
As	O
the	O
successor	O
of	O
Windows	B-Application
2.1	I-Application
,	O
it	O
was	O
also	O
released	O
in	O
Windows/286	O
and	O
Windows/386	O
editions	O
,	O
with	O
some	O
minor	O
changes	O
in	O
memory	O
management	O
and	O
updates	O
regarding	O
printing	O
options	O
.	O
</s>
<s>
Changes	O
to	O
the	O
user	B-Application
interface	I-Application
did	O
not	O
occur	O
in	O
this	O
version	O
,	O
and	O
instead	O
,	O
Microsoft	O
had	O
increased	O
its	O
performance	O
and	O
added	O
enhanced	O
memory	O
management	O
.	O
</s>
<s>
The	O
Windows/286	O
variant	O
introduced	O
LIM	O
4.0	O
boards	O
to	O
store	O
and	O
swap	O
executable	O
code	O
.	O
</s>
<s>
Windows/386	O
allows	O
sharing	O
a	O
single	O
printer	O
to	O
multiple	O
windows	O
.	O
</s>
<s>
Microsoft	O
has	O
also	O
introduced	O
a	O
disk-caching	O
program	O
,	O
SmartDrive	B-Application
,	O
while	O
third-party	O
developers	O
had	O
introduced	O
more	O
apps	O
to	O
Windows	B-Application
2.1	I-Application
and	O
2.11	O
.	O
</s>
<s>
The	O
official	O
system	O
requirements	O
for	O
Windows	B-Application
2.1	I-Application
include	O
the	O
following	O
:	O
</s>
<s>
Windows	B-Application
2.1	I-Application
is	O
shipped	O
with	O
1.2	O
MB	O
5¼-inch	O
or	O
720K	O
3½-inch	O
floppy	O
disks	O
.	O
</s>
<s>
The	O
Windows/386	O
variant	O
also	O
comes	O
with	O
user	O
's	O
guides	O
,	O
a	O
quick-reference	O
card	O
and	O
a	O
manual	O
that	O
explains	O
the	O
features	O
of	O
the	O
386	B-General_Concept
variant	O
.	O
</s>
<s>
The	O
enhancements	O
that	O
were	O
introduced	O
in	O
Windows	B-Application
2.1	I-Application
are	O
considered	O
to	O
have	O
had	O
improved	O
the	O
operating	B-Application
environment	I-Application
.	O
</s>
<s>
The	O
Windows/386	O
variant	O
has	O
good	O
level	O
of	O
functionality	O
,	O
and	O
it	O
lets	O
applications	O
run	O
in	O
full	O
-	O
or	O
partial-screen	O
windows	O
,	O
while	O
the	O
operating	B-Application
environment	I-Application
also	O
slows	O
down	O
when	O
running	O
graphic-based	O
applications	O
.	O
</s>
<s>
InfoWorld	O
rated	O
Windows/386	O
an	O
excellent	O
value	O
.	O
</s>
<s>
Alongside	O
DESQview	B-Operating_System
386	I-Operating_System
,	O
they	O
were	O
considered	O
to	O
be	O
the	O
most	O
popular	O
386	B-General_Concept
environments	O
by	O
1989	O
,	O
although	O
DESQview	B-Operating_System
386	I-Operating_System
is	O
considered	O
to	O
be	O
more	O
flexible	O
than	O
Windows/386	O
.	O
</s>
<s>
Compared	O
to	O
other	O
80386-based	O
systems	O
,	O
Windows/386	O
requires	O
less	O
DOS	O
memory	O
.	O
</s>
<s>
The	O
price	O
tag	O
for	O
Windows/286	O
sat	O
at	O
,	O
while	O
the	O
Windows/386	O
variant	O
cost	O
.	O
</s>
<s>
By	O
January	O
1990	O
,	O
the	O
sales	O
of	O
Microsoft	B-Application
Windows	I-Application
had	O
reached	O
less	O
than	O
two	O
million	O
.	O
</s>
<s>
It	O
was	O
succeeded	O
by	O
Windows	B-Application
3.0	I-Application
released	O
in	O
1990	O
,	O
and	O
after	O
that	O
,	O
Windows	B-Application
3.1	I-Application
in	O
1992	O
,	O
and	O
is	O
considered	O
to	O
be	O
the	O
first	O
version	O
of	O
Microsoft	B-Application
Windows	I-Application
to	O
perform	O
well	O
both	O
critically	O
and	O
commercially	O
.	O
</s>
