Apple introduced the Macintosh Plus on January 16, 1986 as a replacement for the Macintosh 512K. The Macintosh Plus has an 8 MHz 68000 processor and an internal 800K floppy disk drive. The Plus supports up to 4 MB of RAM. My Macintosh Plus has only 1 MB of RAM and is branded "Macintosh Plus 1 MB" on the back of the computer. I purchased it in 2006 on eBay for way too much money, but it is a very well preserved Plus, almost unused. This Mac is a later model Plus with the "platinum" colored case. Platinum was Apple's term for their light gray-blue cases. Originally the Plus was beige like the 512K, 512Ke, and 128K. This case color was pervasive at Apple Computer from the late 1980s through to the introduction of the iMac in 1998. Another example of a beige chassis turned platinum during this time is the Apple IIe Platinum.
The Plus is a significant improvement over the previous compact Macs primarily due to the addition of the SCSI bus. Previous Macs did not have SCSI, thus making it more difficult to find a suitable external hard drive able to connect through the drive port, the printer port, or the modem port. These drives are considerably slower (as much as 4 times slower) than external SCSI hard drives. My Plus has an external Cutting Edge 30 MB SCSI hard drive. The Mac Plus does not have the capacity (no connector on the motherboard) to add an internal hard drive like those found in the Macintosh SE and later compact Macs, nor does it support a 1.4 MB high-density external or internal floppy drive. The Plus has the following ports: one DB-9 mouse port, one DB-19 disk drive port, one DB-25 SCSI port, one serial DIN-8 RS-422 printer port, one serial DIN-8 RS-422 modem port, and an audio out port. The Plus does not have an internal microphone or microphone port.
Macintosh Plus ports
Cutting Edge 30 MB external hard drive
Hard drive and mouse connected to back of computer
The keyboard is connected on the front of the computer using the same connector as previous Macs. It is similar to an RJ-11 telephone connector. The keyboard is an extended version of the original Macintosh keyboard, complete with cursor keys and a numeric keypad. The Plus does not have ADB (Apple Desktop Bus) like later compact Macs beginning with the Macintosh SE. It uses Apple's original, somewhat clunky, DB-9 mouse. My Plus came with a new, never used DB-9 mouse.
Macintosh Plus keyboard
Macintosh Plus mouse
The Plus does not have an internal fan. That makes it necessary to have the vented top, a feature later dropped on the SE and Classic, which have a fan. It is cooled through convection, similar to fan-less CRT iMacs beginning with the iMac G3/400. Apple's primary reason for not including a fan was to reduce noise. I personally think that the real source of noise on the compact Macs is an external or internal hard drive. I have heard stories of damage developing over time due to the internal heat generated in the convection-cooled Plus. I don't plan to stress this system out very much. It probably won't see more than five hours of use a week.
Macintosh Plus convection vents
Another difference between the Plus and later compact Macs is the PRAM battery. Most later generation Macs use a 3.6V lithium battery that attaches to the motherboard through a battery connector. An early version of the Macintosh SE has this battery soldered directly to the motherboard, but all later compact Macs have the standard Macintosh battery connector still present on modern Macs. The Plus uses a 4.5V alkaline, (type #523) battery that attaches into a battery chamber on the back of the computer. Unfortunately, these batteries are hard to find today and are no longer in production. Fortunately, my Plus' battery still works.
(Click) Changing PRAM Battery:
My Plus runs Mac OS 6 (Finder 6.1.4, System 6.0.4). It could reasonably handle 7.1, but it officially supports up to Mac OS 7.5.5. However, since my Plus only has 1 MB of RAM, installing Mac OS 7.5.5 would not be advisable.
The Macintosh Plus is a very important computer in the history of Apple Computer. It set up many of the standards that Apple followed for over a decade going forward. It was the first compact Mac to use SCSI. The Plus also was the first compact Mac to have 2 mini DIN-8 RS-422 ports for printer and modem. It must be noted that the Mac Plus was an all-around good computer that addressed many of the deficiencies of the original Macintosh 128K through the 512Ke. It had ample RAM for the time, the ability to connect a fast hard drive through the SCSI port, used industry standard 800K double density floppy disks, and could connect to a variety of peripherals through the SCSI port or RS-422 ports. Even after the introduction of the Macintosh SE in 1987, Apple continued to produce the Plus and sell it as the low-cost alternative in its line of computers. The Plus stayed in production for an astounding 4 years and 10 months making it the longest lived of all Macs, second to the Apple IIe, which was in production for nearly 10 years.
One of the Plus' claims to fame is its appearance in Star Trek IV, The Voyage Home (Paramount, 1986). The Star Trek crew traveled back in time in a stolen Klingon Bird of Prey to 1986 San Francisco in order to save Earth in the future. Scotty and McCoy are trying to acquire parts to build a water tank in the spaceship to hold humpback whales (it's a long story, see the movie if you are confused). Scotty and McCoy visit a plexiglass manufacturer to offer them the secret of "Transparent Aluminum" in exchange for materials needed to build the tank. Scotty uses a beige Macintosh Plus in the plant office to show the plant manager the molecular structure of Transparent Aluminum. He looks at the computer and says, "Computer, computer," as if it were going to talk back. McCoy then hands him the mouse in an attempt to help. Scotty then speaks into the mouse like a microphone and says, "Hello computer." The plant manager finally says, "Just use the keyboard!" Scotty sarcastically says, "The keyboard? How quaint!" He then starts typing and magically the formula for Transparent Aluminum appears on the Mac Plus.
Scotty: "Hello computer."
Scotty works the Mac Plus
QuickTime Movie Clip:
Scotty and the Mac Plus (4.4 MB)
This Macintosh Plus is a nice part of my collection. It is practically brand new in appearance. There are no perceptible imperfections, no yellowing or discoloration, and no screen burn. This Macintosh Plus was a great find and I am happy to have it in my vintage Apple collection.