Apple Macintosh Plus (1986)


  • CPU: Motorola MC 68000 7.8336 MHz
  • RAM: 1 MB (up to 4 MB) IBM RAM SIMM's as well as any other 1MB SIMM could be added
  • ROM: 128 KB
  • Graphic Modes: 512 x 342 dots
  • Colors: Monochrome
  • Sound: Tone Generator & Digital-Analog converter (22kHz sampling rate)
  • I/O Ports: RS 232/422 x 2 for printer and modem, SCSI, external F.D. unit, ext. loudspeaker
  • Keyboard: Full-stroke 78 keys with numeric keypad
  • Built In Media: One 3.5“ 800 KB disk-drive
  • OS: Macintosh System (from 3.2 to 7.5)
  • Built In Language: None


MESS supports the emulation of macplus with two hard disks and two floppy drives connected. The former ones use “harddisk1” (hard1) and “harddisk2” (hard2) for .chd and .hd files; the latter ones use “floppydisk1” (flop1) and “floppydisk2” (flop2) for disk images in .dsk, .img and .image.dc format.


This system requires full keyboard emulation to work correctly. At startup, full keyboard emulation mode is enabled by default. Whilst in full keyboard emulation mode, some key associated functionality may be disabled (like the ESC key for EXIT). The keyboard emulation mode is toggled using the “Scroll Lock” key (by default).

RAM options

Different RAM configurations are possible for the macplus in MESS. You can switch between them, changing the -ramsize parameter. At command line, you simply have to add -ramsize ram_value, where ram_value can assume one of the following values

1m (default)

History and Trivia

Introduced on 16th January 1986, the Macintosh Plus was the first real improvement of the original Macintosh 128k (The Macintosh 512k was just a Mac 128k with 512 kb of RAM). It had several new features.

The extended ROM held the new version of operating system: it supported hard disk units, the SCSI bus, and the new file system: HFS (Hierarchical File System), along with many other new features (Time Manager etc.). Additionally, various routines and managers previously located in RAM (Appletalk manager, RAM Serial Driver, Standard File Package etc.) had been moved to ROM.

The new floppy disk unit could use double-sided 800 kb disks (compared to single-sided 400 kb for the Macintosh 128k). It came with 1 Mb of RAM, and could easily be expanded to 4 Mb, using standard 1Mb SIMMs. It had an enhanced keyboard with a numeric pad and last but not least, it had a SCSI 1 interface which allowed to connect several high speed peripherals (maximal transfer rate of 312 kbyte/s on Mac Plus - which is incredibly inefficient) such as hard disks and scanners.

Although the Mac Plus was made obsolete in march 1987 by the new Macintosh series (Macintosh SE and the Macintosh II), it remained in production as a cheaper alternative until the introduction of Macintosh Classic on 15th october 1990. This makes Macintosh Plus the longest lived Macintosh ever produced.

(info from

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