<s>
The	O
Macintosh	B-Device
Plus	I-Device
computer	O
is	O
the	O
third	O
model	O
in	O
the	O
Macintosh	B-Device
line	I-Device
,	O
introduced	O
on	O
January	O
16	O
,	O
1986	O
,	O
two	O
years	O
after	O
the	O
original	B-Device
Macintosh	I-Device
and	O
a	O
little	O
more	O
than	O
a	O
year	O
after	O
the	O
Macintosh	B-Device
512K	I-Device
,	O
with	O
a	O
price	O
tag	O
of	O
US$	O
2,599	O
.	O
</s>
<s>
As	O
an	O
evolutionary	O
improvement	O
over	O
the	O
512K	O
,	O
it	O
shipped	O
with	O
1MB	O
of	O
RAM	O
standard	O
,	O
expandable	O
to	O
4MB	O
,	O
and	O
an	O
external	O
SCSI	B-Architecture
peripheral	O
bus	O
,	O
among	O
smaller	O
improvements	O
.	O
</s>
<s>
Originally	O
,	O
the	O
computer	O
's	O
case	O
was	O
the	O
same	O
beige	O
color	O
as	O
the	O
original	B-Device
Macintosh	I-Device
,	O
Pantone	O
453	O
;	O
however	O
,	O
in	O
1987	O
,	O
the	O
case	O
color	O
was	O
changed	O
to	O
the	O
long-lived	O
,	O
warm	O
gray	O
"	O
Platinum	O
"	O
color	O
.	O
</s>
<s>
It	O
is	O
the	O
earliest	O
Macintosh	B-Device
model	O
able	O
to	O
run	O
System	B-Application
Software	I-Application
5	O
,	O
System	B-Protocol
6	I-Protocol
,	O
and	O
System	B-Operating_System
7	I-Operating_System
,	O
up	O
to	O
System	B-Operating_System
7.5.5	I-Operating_System
,	O
but	O
not	O
System	B-Operating_System
7.5.2	I-Operating_System
.	O
</s>
<s>
Bruce	O
Webster	O
of	O
BYTE	B-Application
reported	O
a	O
rumor	O
in	O
December	O
1985	O
:	O
"	O
Supposedly	O
,	O
Apple	O
will	O
be	O
releasing	O
a	O
Big	O
Mac	B-Device
by	O
the	O
time	O
this	O
column	O
sees	O
print	O
:	O
said	O
Mac	B-Device
will	O
reportedly	O
come	O
with	O
1	O
megabyte	O
of	O
RAM	O
...	O
the	O
new	O
128K-byte	O
ROM	O
...	O
and	O
a	O
double-sided	O
(	O
800K	O
bytes	B-Application
)	O
disk	O
drive	O
,	O
all	O
in	O
the	O
standard	O
Mac	B-Device
box	O
"	O
.	O
</s>
<s>
Introduced	O
as	O
the	O
Macintosh	B-Device
Plus	I-Device
,	O
it	O
was	O
the	O
first	O
Macintosh	B-Device
model	O
to	O
include	O
a	O
SCSI	B-Architecture
port	O
,	O
which	O
launched	O
the	O
popularity	O
of	O
external	O
SCSI	B-Architecture
devices	O
for	O
Macs	B-Device
,	O
including	O
hard	O
disks	O
,	O
tape	O
drives	O
,	O
CD-ROM	O
drives	O
,	O
printers	O
,	O
Zip	B-Operating_System
drives	I-Operating_System
,	O
and	O
even	O
monitors	O
.	O
</s>
<s>
The	O
SCSI	B-Architecture
implementation	O
of	O
the	O
Plus	O
was	O
engineered	O
shortly	O
before	O
the	O
initial	O
SCSI	B-Architecture
spec	O
was	O
finalized	O
and	O
,	O
as	O
such	O
,	O
is	O
not	O
100%	O
SCSI-compliant	O
.	O
</s>
<s>
SCSI	B-Architecture
ports	O
remained	O
standard	O
equipment	O
for	O
all	O
Macs	B-Device
until	O
the	O
introduction	O
of	O
the	O
iMac	B-Device
in	O
1998	O
.	O
</s>
<s>
The	O
Macintosh	B-Device
Plus	I-Device
was	O
the	O
last	O
classic	O
Mac	B-Device
to	O
have	O
a	O
phone	O
cord-like	O
port	O
on	O
the	O
front	O
of	O
the	O
unit	O
for	O
the	O
keyboard	O
,	O
as	O
well	O
as	O
the	O
DE-9	O
connector	O
for	O
the	O
mouse	O
;	O
models	O
released	O
after	O
the	O
Macintosh	B-Device
Plus	I-Device
would	O
use	O
ADB	B-Device
ports	I-Device
.	O
</s>
<s>
The	O
Mac	B-Device
Plus	I-Device
was	O
the	O
first	O
Apple	O
computer	O
to	O
utilize	O
user-upgradable	O
SIMM	B-General_Concept
memory	O
modules	O
instead	O
of	O
single	O
DIP	O
DRAM	O
chips	O
.	O
</s>
<s>
Four	O
SIMM	B-General_Concept
slots	O
were	O
provided	O
and	O
the	O
computer	O
shipped	O
with	O
four	O
256	O
KB	O
SIMMs	B-General_Concept
,	O
for	O
1	O
MB	O
total	O
RAM	O
.	O
</s>
<s>
By	O
replacing	O
them	O
with	O
1	O
MB	O
SIMMs	B-General_Concept
,	O
it	O
was	O
possible	O
to	O
have	O
4	O
MB	O
of	O
RAM	O
.	O
</s>
<s>
(	O
Although	O
30-pin	O
SIMMs	B-General_Concept
could	O
support	O
up	O
to	O
16	O
MB	O
total	O
RAM	O
,	O
the	O
Mac	B-Device
Plus	I-Device
motherboard	O
had	O
only	O
22	O
address	O
lines	O
connected	O
,	O
for	O
a	O
4	O
MB	O
maximum	O
.	O
)	O
</s>
<s>
It	O
has	O
what	O
was	O
then	O
a	O
new	O
-inch	O
double-sided	O
800	O
KB	O
floppy	B-Device
drive	I-Device
,	O
offering	O
double	O
the	O
capacity	O
of	O
floppy	B-Device
disks	I-Device
from	O
previous	O
Macs	B-Device
,	O
along	O
with	O
backward	O
compatibility	O
.	O
</s>
<s>
The	O
drive	O
is	O
controlled	O
by	O
the	O
same	O
IWM	B-General_Concept
chip	O
as	O
in	O
previous	O
models	O
,	O
implementing	O
variable	B-Architecture
speed	I-Architecture
GCR	B-Device
.	O
</s>
<s>
The	O
drive	O
was	O
still	O
completely	O
incompatible	O
with	O
PC	B-Device
drives	O
.	O
</s>
<s>
The	O
800KB	O
drive	O
has	O
two	O
read/write	O
heads	O
,	O
enabling	O
it	O
to	O
simultaneously	O
use	O
both	O
sides	O
of	O
the	O
floppy	B-Device
disk	I-Device
and	O
thereby	O
double	O
storage	O
capacity	O
.	O
</s>
<s>
Like	O
the	O
400KB	O
drive	O
before	O
it	O
,	O
a	O
companion	O
Macintosh	B-Device
800K	O
External	O
Drive	O
was	O
an	O
available	O
option	O
.	O
</s>
<s>
The	O
Mac	B-Device
Plus	I-Device
has	O
128KB	O
of	O
ROM	O
on	O
the	O
motherboard	O
,	O
which	O
is	O
double	O
the	O
amount	O
of	O
ROM	O
in	O
previous	O
Macs	B-Device
;	O
the	O
ROMs	O
included	O
software	O
to	O
support	O
SCSI	B-Architecture
,	O
the	O
then-new	O
800KB	O
floppy	B-Device
drive	I-Device
,	O
and	O
the	O
Hierarchical	B-Application
File	I-Application
System	I-Application
(	O
HFS	B-Application
)	O
,	O
which	O
uses	O
a	O
true	O
directory	O
structure	O
on	O
disks	O
(	O
as	O
opposed	O
to	O
the	O
earlier	O
MFS	O
,	O
Macintosh	B-Application
File	I-Application
System	I-Application
in	O
which	O
all	O
files	O
were	O
stored	O
in	O
a	O
single	O
directory	O
,	O
with	O
one	O
level	O
of	O
pseudo-folders	O
overlaid	O
on	O
them	O
)	O
.	O
</s>
<s>
For	O
programmers	O
,	O
the	O
fourth	O
Inside	B-Operating_System
Macintosh	I-Operating_System
volume	O
details	O
how	O
to	O
use	O
HFS	B-Application
and	O
the	O
rest	O
of	O
the	O
Mac	B-Device
Plus	I-Device
's	O
new	O
system	B-Application
software	I-Application
.	O
</s>
<s>
The	O
Plus	O
still	O
did	O
not	O
include	O
provision	O
for	O
an	O
internal	O
hard	O
drive	O
and	O
it	O
would	O
be	O
over	O
nine	O
months	O
before	O
Apple	O
would	O
offer	O
a	O
SCSI	B-Architecture
drive	B-Device
replacement	I-Device
for	O
the	O
slow	O
Hard	O
Disk	O
20	O
.	O
</s>
<s>
It	O
would	O
be	O
well	O
over	O
a	O
year	O
before	O
Apple	O
would	O
offer	O
the	O
first	O
internal	O
hard	O
disk	O
drive	O
in	O
any	O
Macintosh	B-Device
.	O
</s>
<s>
A	O
compact	O
Mac	B-Device
,	O
the	O
Plus	O
has	O
a	O
512	O
×	O
342	O
pixel	B-Algorithm
monochrome	O
display	O
with	O
a	O
resolution	O
of	O
72PPI	O
,	O
identical	O
to	O
that	O
of	O
previous	O
Macintosh	B-Device
models	O
.	O
</s>
<s>
Unlike	O
earlier	O
Macs	B-Device
,	O
the	O
Mac	B-Device
Plus	I-Device
's	O
keyboard	O
includes	O
a	O
numeric	O
keypad	O
and	O
directional	O
arrow	O
keys	O
and	O
,	O
as	O
with	O
previous	O
Macs	B-Device
,	O
it	O
has	O
a	O
one-button	O
mouse	O
and	O
no	O
fan	O
,	O
making	O
it	O
extremely	O
quiet	O
in	O
operation	O
.	O
</s>
<s>
The	O
lack	O
of	O
a	O
cooling	O
fan	O
in	O
the	O
Mac	B-Device
Plus	I-Device
led	O
to	O
frequent	O
problems	O
with	O
overheating	O
and	O
hardware	O
malfunctions	O
.	O
</s>
<s>
The	O
applications	O
MacPaint	B-Operating_System
and	O
MacWrite	B-Operating_System
were	O
bundled	O
with	O
the	O
Mac	B-Device
Plus	I-Device
.	O
</s>
<s>
After	O
August	O
1987	O
,	O
HyperCard	B-Application
and	O
MultiFinder	O
were	O
also	O
bundled	O
.	O
</s>
<s>
Third-party	O
software	O
applications	O
available	O
included	O
MacDraw	B-Operating_System
,	O
Microsoft	B-Application
Word	I-Application
,	O
Excel	B-Application
,	O
and	O
PowerPoint	B-Application
,	O
as	O
well	O
as	O
Aldus	B-Operating_System
PageMaker	I-Operating_System
.	O
</s>
<s>
Microsoft	B-Application
Excel	I-Application
and	O
PowerPoint	B-Application
(	O
originally	O
by	O
Forethought	O
)	O
were	O
actually	O
developed	O
and	O
released	O
first	O
for	O
the	O
Macintosh	B-Device
,	O
and	O
similarly	O
Microsoft	B-Application
Word	I-Application
1	O
for	O
Macintosh	B-Device
was	O
the	O
first	O
time	O
a	O
GUI	O
version	O
of	O
that	O
software	O
was	O
introduced	O
on	O
any	O
personal	B-Device
computer	I-Device
platform	O
.	O
</s>
<s>
For	O
a	O
time	O
,	O
the	O
exclusive	O
availability	O
of	O
Excel	B-Application
and	O
PageMaker	B-Operating_System
on	O
the	O
Macintosh	B-Device
were	O
noticeable	O
drivers	O
of	O
sales	O
for	O
the	O
platform	O
.	O
</s>
<s>
The	O
case	O
design	O
is	O
essentially	O
identical	O
to	O
the	O
original	B-Device
Macintosh	I-Device
.	O
</s>
<s>
It	O
debuted	O
in	O
beige	O
and	O
was	O
labeled	O
Macintosh	B-Device
Plus	I-Device
on	O
the	O
front	O
,	O
but	O
Macintosh	B-Device
Plus	I-Device
1	O
MB	O
on	O
the	O
back	O
,	O
to	O
denote	O
the	O
1MB	O
RAM	O
configuration	O
with	O
which	O
it	O
shipped	O
.	O
</s>
<s>
Among	O
other	O
design	O
changes	O
,	O
it	O
included	O
the	O
same	O
trademarked	O
inlaid	O
Apple	O
logo	O
and	O
recessed	O
port	O
icons	O
as	O
the	O
Apple	O
IIc	O
and	O
IIGS	B-Device
before	O
it	O
,	O
but	O
it	O
essentially	O
retained	O
the	O
original	O
design	O
.	O
</s>
<s>
An	O
upgrade	O
kit	O
was	O
offered	O
for	O
the	O
earlier	O
Macintosh	B-Device
128K	I-Device
and	O
Macintosh	O
512K/enhanced	O
,	O
which	O
includes	O
a	O
new	O
motherboard	O
,	O
floppy	B-Device
disk	I-Device
drive	I-Device
and	O
rear	O
case	O
.	O
</s>
<s>
Because	O
of	O
this	O
,	O
there	O
is	O
no	O
"	O
Macintosh	B-Device
Plus	I-Device
"	O
on	O
the	O
front	O
of	O
upgraded	O
units	O
,	O
and	O
the	O
Apple	O
logo	O
is	O
recessed	O
and	O
in	O
the	O
bottom	O
left	O
hand	O
corner	O
of	O
the	O
front	O
case	O
.	O
</s>
<s>
However	O
,	O
the	O
label	O
on	O
the	O
back	O
of	O
the	O
case	O
reads	O
"	O
Macintosh	B-Device
Plus	I-Device
1MB	O
"	O
.	O
</s>
<s>
The	O
Mac	B-Device
Plus	I-Device
itself	O
can	O
be	O
upgraded	O
further	O
with	O
the	O
use	O
of	O
third-party	O
accelerators	O
.	O
</s>
<s>
When	O
these	O
are	O
clipped	O
or	O
soldered	O
onto	O
the	O
68000	B-Device
processor	O
,	O
a	O
32MHz	O
68030	O
processor	O
can	O
be	O
used	O
,	O
and	O
up	O
to	O
16MB	O
RAM	O
.	O
</s>
<s>
There	O
is	O
a	O
program	O
available	O
called	O
Mini	B-Application
vMac	I-Application
that	O
can	O
emulate	B-Application
a	O
Mac	B-Device
Plus	I-Device
on	O
a	O
variety	O
of	O
platforms	O
,	O
including	O
Unix	B-Application
,	O
Windows	B-Application
,	O
DOS	B-Device
,	O
classic	B-Application
Mac	I-Application
OS	I-Application
,	O
macOS	B-Application
,	O
Pocket	B-Device
PC	I-Device
,	O
iOS	B-Application
,	O
Nintendo	B-Device
DS	I-Device
and	O
even	O
Texas	O
Instruments	O
 '	O
TI-Nspire	B-Device
graphing	O
calculator	O
line	O
.	O
</s>
<s>
Although	O
the	O
Macintosh	B-Device
Plus	I-Device
would	O
become	O
overshadowed	O
by	O
two	O
new	O
Macintoshes	B-Device
,	O
the	O
Macintosh	B-Device
SE	I-Device
and	O
the	O
Macintosh	B-Device
II	I-Device
in	O
March	O
1987	O
,	O
it	O
remained	O
in	O
production	O
as	O
a	O
cheaper	O
alternative	O
until	O
the	O
introduction	O
of	O
the	O
Macintosh	B-Device
Classic	I-Device
on	O
October	O
15	O
,	O
1990	O
.	O
</s>
<s>
This	O
made	O
the	O
Macintosh	B-Device
Plus	I-Device
the	O
longest-produced	O
Macintosh	B-Device
model	O
,	O
having	O
been	O
on	O
sale	O
unchanged	O
for	O
1,734	O
days	O
,	O
a	O
record	O
not	O
surpassed	O
until	O
the	O
second-generation	O
Mac	B-Device
Pro	I-Device
in	O
2018	O
.	O
</s>
<s>
It	O
continued	O
to	O
be	O
supported	O
by	O
versions	O
of	O
the	O
classic	B-Application
Mac	I-Application
OS	I-Application
up	O
to	O
version	B-Operating_System
7.5.5	I-Operating_System
,	O
released	O
in	O
1996	O
.	O
</s>
<s>
Additionally	O
,	O
during	O
its	O
period	O
of	O
general	O
market	O
relevance	O
,	O
it	O
was	O
heavily	O
discounted	O
like	O
the	O
512K/512Ke	O
before	O
it	O
and	O
offered	O
to	O
the	O
educational	O
market	O
badged	O
as	O
the	O
"	O
Macintosh	B-Device
Plus	I-Device
ED	I-Device
"	O
.	O
</s>
<s>
Due	O
to	O
its	O
popularity	O
,	O
long	O
life	O
and	O
its	O
introduction	O
of	O
many	O
features	O
that	O
would	O
become	O
mainstays	O
of	O
the	O
Macintosh	B-Device
platform	O
for	O
years	O
,	O
the	O
Plus	O
was	O
a	O
common	O
"	O
base	O
model	O
"	O
for	O
many	O
software	O
and	O
hardware	O
products	O
.	O
</s>
<s>
The	O
lack	O
of	O
fan	O
could	O
cause	O
the	O
life	O
of	O
a	O
Macintosh	B-Device
Plus	I-Device
to	O
end	O
early	O
for	O
some	O
users	O
.	O
</s>
<s>
As	O
in	O
most	O
early	O
compact	O
Macs	B-Device
,	O
the	O
problem	O
was	O
common	O
in	O
the	O
yoke	O
connector	O
,	O
flyback	O
transformer	O
,	O
and	O
horizontal	O
drive	O
coupling	O
capacitor	O
.	O
</s>
<s>
From	O
the	O
debut	O
of	O
the	O
Macintosh	B-Device
128K	I-Device
through	O
the	O
Macintosh	B-Device
Plus	I-Device
,	O
various	O
third-party	O
cooling	O
add-ons	O
were	O
available	O
to	O
help	O
increase	O
airflow	O
through	O
the	O
unit	O
.	O
</s>
<s>
Apple	O
reorganized	O
the	O
compact	O
Macintosh	B-Device
case	O
to	O
accommodate	O
a	O
fan	O
with	O
the	O
release	O
of	O
the	O
Macintosh	B-Device
SE	I-Device
,	O
which	O
optionally	O
included	O
a	O
heat-generating	O
internal	O
hard	O
disk	O
.	O
</s>
<s>
The	O
initial	O
ROM	O
was	O
replaced	O
after	O
the	O
first	O
two	O
months	O
as	O
it	O
had	O
a	O
serious	O
bug	O
which	O
prevented	O
the	O
Mac	B-Device
from	O
booting	O
if	O
an	O
external	O
SCSI	B-Architecture
device	O
was	O
powered	O
off	O
.	O
</s>
<s>
The	O
second	O
revision	O
fixed	O
a	O
problem	O
with	O
some	O
SCSI	B-Architecture
devices	O
that	O
could	O
send	O
the	O
Mac	B-Device
into	O
an	O
endless	O
reset	O
at	O
POST	B-Device
.	O
</s>
