Apple  Macintosh 512K
Previous System
apl_mac_512
Next System

Macintosh 512K

The Macintosh 512K was the successor of the Macintosh 128K (or simply Macintosh) and introduced by Apple Computer in 1984. The machine was nicknamed "fat Mac" because of it's larger memory, 512KByte. The machine was however technically different from the original Macintosh. It had a completely redesigned logic board to easily accomodate both 128KByte and 512KByte RAM during manufacturing. The new design allowed for easier upgrades of the Macintosh 128K.

The increased memory allowed for more powerful applications, such as the popular Microsoft Multiplan spreadsheet application. The other specifications were similar to the original Macintosh

Motorola 68000 CPU Family

The Motorola 68000 is a 16/32-bit microprocessor that was first released in 1979. It was widely used in computers and other electronic devices during the 1980s and early 1990s. The 68000 was known for its advanced architecture, which included a 32-bit internal bus and a 24-bit address bus, allowing it to access up to 16 megabytes of memory. This made it more powerful than many other processors of its time, such as the Intel 8086 and Zilog Z80. It was also designed to be highly modular and expandable, with a large number of on-chip and off-chip peripherals.

Some of the most famous and successful computers that used the 68000 was the Commodore Amiga and the Atari ST, both of which were popular in the home and personal computer markets. Additionally, it was also used in workstations, such as the Sun 3 and Apollo DN3000, and in a wide variety of embedded systems and industrial control systems. The 68000 was also used in the Macintosh, the first model of the Macintosh was powered by a Motorola 68000 CPU. The processor was eventually succeeded by the 68020 and 68030, which offered improved performance and additional features.

The 68000 has a 32-bit instruction set, with 32-bit registers and a 16-bit internal data bus. The address bus is 24-bit and does not use memory segmentation, making it easier to address memory. There are three ALU's (Arithmetic Logic Unit), two for calculating addresses, and one for data, and the chip has a 16-bit external address bus.

The 68000 architecture was expanded with 32-bit ALUs, and caches. Here is a list with some 680x0 versions and their major improvements:

  • 68010 - Virtual memory support
  • 68020 - 32-bit ALU & Instruction Cache
  • 68030 - On-Chip MMU, 2x 256 byte cache
  • 68040 - 2x 4K Cache, 6 stage pipeline, FPU
  • 68LC040 - No Floating Point Unit (FPU)
  • 68060 - 2x 8K Cache, 10 stage pipelinet

Technical Details
Released 1984 Brand Apple Type Apple Macintosh Name Macintosh 512K CPU Class 68000 CPU Motorola 68000 @7.8336MHz Memory RAM: 512kB Sound Chip TTL Logic for PWM Sound 8-bit Pulse-width modulation Display Chip none Display 512x342 Mono Best Color monochrome Best Graphics 512x342 monochrome Sprites none System OS MacOS Storage Internal 3.5" 400K Single Sided Disk Drive
Related Systems
 
Apple Series I
 
Apple Series II
 
Apple Series III
 
Apple Macintosh
» 
Macintosh  512K (1984)
 
Apple Macintosh II
 
Apple Macintosh LC & Quadra
 
Apple Newton
Related Media
 
Apple Macintosh
Books about the Apple Macintosh, the first mass-market personal computer with a graphical user interface.
 
68' Micro Journal
Magazine devoted to the 68xx user
 
InCider and A+
InCider Magazine for Apple Computers, later fused with A+
 
Peeker Magazine
Peeker, a German language magazine for Apple Computer users.
World Wide Web Links
 
Wikipedia: Motorola 68000 CPU Family
WikiPedia page on the Motorola 68000 series of processors