The MACINTOSH PLUS computer is the third model in the
introduced on January 16, 1986, two years after the original Macintosh
and a little more than a year after the
Macintosh 512K , with a price
tag of US$2599. As an evolutionary improvement over the 512K, it
shipped with 1 MB of RAM standard, expandable to 4 MB, and an external
SCSI peripheral bus, among smaller improvements. It originally had the
same generally beige-colored case as the original
453" ), but in 1987, the case color was changed to the long-lived,
warm gray "Platinum" color. It is the earliest
Macintosh model able
System 7 OS.
* 1 Overview
* 2 Long production life
* 3 Problems
* 3.1 ROM revisions
* 4 Emulators
* 5 Timeline of compact
* 6 See also
* 7 References
* 8 External links
Introduced as the
Macintosh Plus, it was the first
Macintosh model to
SCSI port, which launched the popularity of external SCSI
devices for Macs, including hard disks, tape drives, CD-ROM drives,
printers, and even monitors. The
SCSI implementation of the Plus was
engineered shortly before the initial
SCSI spec was finalized and, as
such, is not 100% SCSI-compliant.
SCSI ports remained standard
equipment for all Macs until the introduction of the iMac in 1998,
which replaced most of Apple's "legacy ports " with
Macintosh Plus was the last classic Mac to have a phone cord-like
port on the front of the unit for the keyboard , as well as the DE-9
connector for the mouse ; models released after the
would use ADB ports.
The Mac Plus was the first Apple computer to utilize SIMM memory
instead of single DIP DRAMs. Four slots were provided and the computer
shipped with four 256k SIMMs for 1MB total. By replacing them with 1MB
SIMMs, it was possible to have 4MB of RAM. Although 30-pin SIMMs could
support up to 16MB total RAM, the motherboard had only 22 address
lines connected for 4MB.
It has what was then a new 3.5-inch double-sided 800 KB floppy drive
, offering double the capacity of floppy disks for previous Macs,
along with backward compatibility. The then-new drive is controlled by
the same IWM chip as in previous models, implementing variable speed
GCR . The drive was still completely incompatible with PC drives. The
800 KB drive has two read/write heads, enabling it to simultaneously
use both sides of the floppy disk and thereby double storage capacity.
Like the 400 KB drive before it, a companion
Macintosh 800K External
Drive was an available option. However, with the increased storage
capacity combined with 2-4x the available RAM, the external drive was
less of a necessity than it had been with the 128K and 512K.
The Mac Plus has 128 KB of ROM on the motherboard, which is double
the amount of ROM that's in previous Macs; the then-new System
software and ROMs included routines to support SCSI, the then-new 800
KB floppy drive, and the Hierarchical
File System (HFS), which uses a
true directory structure on disks (as opposed to the earlier MFS,
File System in which all files were stored in a single
directory, with one level of pseudo-folders overlaid on them). For
programmers, the fourth
Inside Macintosh volume details how to use HFS
and the rest of the Mac Plus's new system software. This new filing
system allows it to use the first hard drive Apple developed for the
512K, the IWM floppy disk-based
Hard Disk 20 and the then-new ROMs
Macintosh to use the drive as a startup disk for the first
time. The Plus still did not include provision for an internal hard
drive and it would be over nine months before Apple would offer a SCSI
drive replacement for the slow Hard Disk 20. It would be well over a
year before Apple would offer the first internal hard disk drive in
A compact Mac , the Plus has a 9-inch (23 cm) 512×342 pixel
monochrome display with a resolution of 72 PPI , identical to that of
Macintosh models. Unlike earlier Macs, the Mac Plus's
keyboard includes a numeric keypad and directional arrow keys and, as
with previous Macs, it has a one-button mouse and no fan, making it
extremely quiet in operation. The lack of a cooling fan in the Mac
Plus led to frequent problems with overheating and hardware
MacWrite were bundled with the Mac
Plus. After August 1987,
MultiFinder were also bundled.
Third-party software applications available included
Microsoft Word , Excel , and PowerPoint , as well as
Microsoft Excel and PowerPoint (originally by Forethought
) were actually developed and released first for the Macintosh, and
similarly Microsoft Word 1 for
Macintosh was the first time a GUI
version of that software was introduced on any personal computer
platform. For a time, the exclusive availability of Excel and
PageMaker on the
Macintosh were noticeable drivers of sales for the
Apple Macintosh Plus at the Design Museum in
The case design is essentially identical to the original
It debuted in beige and was labeled
Macintosh Plus on the front, but
Macintosh Plus 1 MB on the back, to denote the 1 MB RAM configuration
with which it shipped. In January 1987 it transitioned to Apple's
long-lived platinum-gray color with the rest of the Apple product
line, and the keyboard's keycaps changed from brown to gray. In
January 1988, with reduced RAM prices, Apple began shipping 2- and 4-
MB configurations and rebranded it simply as "
Macintosh Plus." Among
other design changes, it included the same trademarked inlaid Apple
logo and recessed port icons as the
Apple IIc and IIGS before it, but
it essentially retained the original design.
An upgrade kit was offered for the earlier
Macintosh 128K and
Macintosh 512K /enhanced , which includes a new motherboard, floppy
disk drive and rear case. The owner retained the front case, monitor,
and analog board. Because of this, there is no "
Macintosh Plus" on the
front of upgraded units, and the Apple logo is recessed and in the
bottom left hand corner of the front case. However, the label on the
back of the case reads "
Macintosh Plus 1MB". The new extended Plus
keyboard could also be purchased. Unfortunately, this upgrade cost
almost as much as a new machine.
The Mac Plus itself can be upgraded further with the use of
third-party accelerators. When these are clipped or soldered onto the
68000 processor, a 32 MHz 68030 processor can be used, and up to 16 MB
RAM. This allows it to run Mac OS 7.6.1 .
There is a program available called
Mini vMac that can emulate a Mac
Plus on a variety of platforms, including
Unix , Windows ,
classic Mac OS , macOS ,
Pocket PC , iOS and even
Nintendo DS .
LONG PRODUCTION LIFE
The "ED" at the end of the model name indicates that this
Macintosh was sold to the educational market.
Although the Mac Plus would become overshadowed by two new Macs (the
Macintosh SE and the
Macintosh II ) in March 1987, it remained in
production as a cheaper alternative until the introduction of the
Macintosh Classic on October 15, 1990. This makes the
Macintosh ever. It continued to be supported by
versions of the classic Mac OS up to version 7.5.5 , released in 1996.
Additionally, during its period of general market relevance, it was
heavily discounted like the 512K/512Ke before it and offered to the
educational market badged as the "
Macintosh Plus ED". Due to its
popularity, long life and its introduction of many features that would
become mainstays of the
Macintosh platform for years, the Plus was a
common "base model" for many software and hardware products.
The lack of fan could cause the life of a
Macintosh Plus to end early
for some users. As the power supply would heat up, solder joints
inside it would fracture causing many problems, such as loss of
deflection in the monitor or a complete loss of power. As in most
early compact Macs, the problem was common in the yoke connector,
flyback transformer, and horizontal drive coupling capacitor. A fan
was also often added to reduce heat when the machine was upgraded to
its full RAM capacity of 4 MB.
From the debut of the
Macintosh 128K through the
various third-party cooling add-ons were available to help increase
airflow through the unit. Apple reorganized the compact
to accommodate a fan with the release of the
Macintosh SE , which
included a heat-generating internal hard disk.
The Plus went through two ROM revisions during its general market
relevance. The initial ROM was replaced after the first two months as
it had a serious bug which prevented the Mac from booting if an
SCSI device was powered off. The second revision fixed a
problem with some
SCSI devices that could send the Mac into an endless
reset at startup.
TIMELINE OF COMPACT MACINTOSH MODELS
See also: Timeline of
Apple Macintosh models
* ^ "The 25 Greatest PCs of All Time". PCWorld. 2006-08-11.
* ^ "History of computer design: Apple Macintosh". Landsnail.com.
1998-05-17. Retrieved 2016-05-20.
* ^ "History of computer design:
Macintosh Plus". Landsnail.com.
1998-05-17. Retrieved 2016-05-20.
* ^ Knight, Dan. "ScuzzyGraph and ScuzzyGraph II". Low End Mac.
Retrieved 10 July 2015.
* ^ "Mac Plus". Low End Mac. Retrieved 2016-05-20.
* ^ "Classic Mac Repair Notes" (PDF). 68kmla.org. Retrieved
* ^ Still Useful after