Apple Macintosh Classic Specs

Redesigned to reduce expense and offer a modernized version of the highly popular Macintosh Classic Macintosh Plus, the Apple Macintosh Classic replaced the Macintosh SE (FD/HD). The Macintosh SE/30 had been released a year earlier as part of Apple’s flagship range. The Classic consisted of a 9 inch monochrome (Black and White Screen) set into a Compact case design.  The motherboard was set into the base of the unit and floppy drive seperated the screen from the computer. Whilst it was slow for its day, the Macintosh Classic made up for it’s lack of speed by being offered for under $1000.  By comparison, the SE/30, upon introduction was over six times that price at $6500.


The Macintosh Classic  featured an 8 MHz 32 bit 68000 processor which unfortunately ran on a 16 bit data bus.


The Computer shipped with either 1 MB or 2 MB of RAM.  It incorporated a Classic-specific “Memory Expansion Card” consisting of a 1 MB daughter card with two open slots,  into which 30 pin 120ns SIMMs could be installed in equal pairs.  A total of 4MB ram could be addressed.


The Macintosh Classic shipped with either a 1.44 MB disk drive or a 1.44 MB disk drive and a 40 MB SCSI hard drive (Model M0435LL/A).  Although the hard drive could be technically upgraded, it required dis-assembly of the case and exposure of the high voltage circuitry that drove the internal CRT tube.

Video & Graphics:

The Mac Classic incorporated  a 9″ monochrome (1 Bit) display. Driven by on-board VRAM, the display offered a resolution of 512×342.  The video could not be upgraded.

Supported OS:

The system was supplied with Macintosh System 6.0.7 and could be user-upgraded to 7.5.5.


Apple Mac Classic PortsThe Mac Classic included somewhat different ports to the Mac 512k and Macintosh 128k. Consisting of ADB (Apple Desktop Bus), Floppy Drive port, SCSI Port (DB 25), Printer (8 pin mini din) and Modem port (again 8 pin mini din).  A sound port was also included consisting of a 3.5mm mono jack port.

Built in Controls:

The Mac classic did away with the brightness knob for the screen and instead integrated it into the system software via the brightness control panel.  The Classic is the only mac to have the ability to boot from ROM Disk by holding down command-option-x-o at startup.

ROM Disk:

The ROM Disk, named “Boot Disk”  is 357 KB in size and contains Finder 6.1.x and System 6.0.3, a combination specifically designed for the Mac Classic. The ROM’s OS includes General, Brightness, Startup Disk, MacsBug and AppleShare Prep.  However, these last two system programs load into 294 KB of the Classic’s RAM. Because this is in ROM, there is no way to add anything to the ROM Disk.

Model Variations:

Apple offered 2 different variations, each with unique order numbers:

  • M0421LL/A, configured with 1 MB of RAM and a 1.44 MB floppy disk.
  • M0435LL/A, configured  with 2 MB of RAM and a 40 MB hard drive was assigned order number .

More Specs:

Introduction Date: October 15, 1990 Discontinued Date: September 14, 1992
Processor Speed: 8 MHz Processor Type: 68000
Processor Upgrade: 3rd Party only FPU: N/A
Details: Third party CPU upogrades included:

  • MicroMac Multispeed (16, 25, or 32 MHz 68030), optional 32 MHz 68882 FPU
  • MicroMac Performer (16 MHz 68030), optional 25 MHz 68882 FPU
  • MicroMac Performer Pro (32 MHz 68030), 64 KB cache, optional 32 MHz 68882 FPU
System Bus Speed: 8 MHz Cache Bus Speed: N/A
Details: N/A
ROM/Firmware Type: Macintosh ROM ROM/Firmware Size: 512k
Details: N/A
L1 Cache: None L2 Cache: N/A
Details: N/A
RAM Type: 30-pin SIMM Min. RAM Speed: 120 ns
Details: N/A
Standard RAM: 1 MB, 2 MB Maximum RAM: 4 MB
Motherboard RAM: 1 MB RAM Slots: 2
Video Card: Integrated VRAM Type: Built-in
Details: N/A
Standard VRAM: N/A Maximum VRAM: N/A
Details: N/A
Built-in Display: 9″ Monochrome Native Resolution: 512×342
Details: N/A
Standard Hard Drive: None, 40 MB Int. HD Interface: SCSI
Standard Optical: None Standard Disk: 1.44 MB (Auto)
Details: N/A
Standard Modem: None Standard Ethernet: None
Details: N/A
Expansion Slots: None Expansion Bays: None*
Details: *If configured without an internal hard drive, one internal 3.5″ bay is available.
Case Type: All-in-One Form Factor: Macintosh Classic
Details: N/A
Apple Order No: M0421LL/A* Apple Subfamily: Macintosh Classic
Apple Model No: M0420, M1420 Gestalt ID: 17
Details: N/A
Battery Type: 3.6V Lithium Battery Life: N/A
Details: N/A
Original Mac OS: 6.0.7 Supported Mac OS: 6.0.7-7.5.1, 7.5.3-7.5.5