The Macintosh 512K is a personal computer that was designed, manufactured and sold by

Apple Computer Apple Inc. is an American multinational technology company headquartered in Cupertino, California, United States. Apple is the largest technology company by revenue (totaling in 2021) and, as of June 2022, is the world's biggest company b ...

from September 1984 to April 1986. It is the first update to the original

Macintosh 128K The Apple Macintosh—later rebranded as the Macintosh 128K—is the original Apple Macintosh personal computer. It played a pivotal role in establishing desktop publishing as a general office function. The motherboard, a CRT monitor, and a fl ...

. It was virtually identical to the previous Macintosh, differing primarily in the amount of built-in random-access memory. The increased memory turned the Macintosh into a more business-capable computer and gained the ability to run more software. It is the earliest Macintosh model that can be used as an AppleShare server and, with a bridge Mac, communicate with modern devices. The Mac 512K originally shipped with Macintosh System 1.1 but was able to run all versions of

Mac OS Two major famlies of Mac operating systems were developed by Apple Inc. In 1984, Apple debuted the operating system that is now known as the "Classic" Mac OS with its release of the original Macintosh System Software. The system, rebranded "M ...

up to System 4.1. It was replaced by the

Macintosh 512Ke The Macintosh 512K ''enhanced'' (512Ke) was introduced in April 1986 as a cheaper alternative to the top-of-the-line Macintosh Plus, which had debuted three months previously. It is the same as the Macintosh 512K but with the 800K disk drive an ...

and the Macintosh Plus. All support for the Mac 512K was discontinued on September 1, 1998.

Features

Processor and memory

Like the Macintosh 128K before it, the 512K contained a

Motorola 68000 The Motorola 68000 (sometimes shortened to Motorola 68k or m68k and usually pronounced "sixty-eight-thousand") is a 16/32-bit complex instruction set computer (CISC) microprocessor, introduced in 1979 by Motorola Semiconductor Products Sector ...

connected to 512 KB of

DRAM Dynamic random-access memory (dynamic RAM or DRAM) is a type of random-access semiconductor memory that stores each bit of data in a memory cell, usually consisting of a tiny capacitor and a transistor, both typically based on metal-oxi ...

by a

16-bit 16-bit microcomputers are microcomputers that use 16-bit microprocessors. A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two mos ...

data bus In computer architecture, a bus (shortened form of the Latin '' omnibus'', and historically also called data highway or databus) is a communication system that transfers data between components inside a computer, or between computers. This ...

. Though the memory had been quadrupled, it could not be upgraded. The large increase earned it the nickname Fat Mac. A 64 KB

ROM Rom, or ROM may refer to: Biomechanics and medicine * Risk of mortality, a medical classification to estimate the likelihood of death for a patient * Rupture of membranes, a term used during pregnancy to describe a rupture of the amniotic sac * R ...

chip boosts the effective memory to 576 KB, but this is offset by the display's 22 KB framebuffer, which is shared with the DMA video controller. This shared arrangement reduces CPU performance by up to 35%. It shared a revised logic board with the rebadged Macintosh 128K (previously just called the Macintosh), which streamlined manufacturing. The resolution of the display was the same, at 512 × 342. Apple sold a memory upgrade for the Macintosh 128K for $995 initially, and reduced the price when 256 kb DRAM prices fell months later.

Software

The applications MacPaint and

MacWrite MacWrite is a WYSIWYG word processor application released along with the first Apple Macintosh systems in 1984. Together with MacPaint, it was one of the two original "killer applications" that propelled the adoption and popularity of the GUI ...

were still bundled with the Mac. Soon after this model was released, several other applications became available, including

MacDraw MacDraw is a discontinued vector graphics drawing application released along with the first Apple Macintosh systems in 1984. MacDraw was one of the first WYSIWYG drawing programs that could be used in collaboration with MacWrite. It was event ...

MacProject MacProject was a project management and scheduling business application released along with the first Apple Macintosh systems in 1984. MacProject was one of the first major business tools for the Macintosh which enabled users to calculate the ...

, Macintosh

Pascal Pascal, Pascal's or PASCAL may refer to: People and fictional characters * Pascal (given name), including a list of people with the name * Pascal (surname), including a list of people and fictional characters with the name ** Blaise Pascal, Frenc ...

and others. In particular, Microsoft Excel, which was written specifically for the Macintosh, required a minimum of 512 KB of RAM, but solidified the Macintosh as a serious business computer. Models with the ''enhanced'' ROM also supported Apple's Switcher, allowing

cooperative multitasking Cooperative multitasking, also known as non-preemptive multitasking, is a style of computer multitasking in which the operating system never initiates a context switch from a running process to another process. Instead, in order to run multiple a ...

among (necessarily few) applications.

New uses

The LaserWriter printer became available shortly after the 512K's introduction, as well as the number pad, mic, tablet, keyboard, mouse, basic mouse, and much more. It utilized Apple's built-in networking scheme

LocalTalk LocalTalk is a particular implementation of the physical layer of the AppleTalk networking system from Apple Computer. LocalTalk specifies a system of shielded twisted pair cabling, plugged into self-terminating transceivers, running at a rate ...

which allows sharing of devices among several users. The 512K was the oldest Macintosh capable of supporting Apple's AppleShare built-in file sharing network, when introduced in 1987. The expanded memory in the 512K allowed it to better handle large word-processing documents and make better use of the graphical user interface and generally increased speed over the 128K model. Color Systems Technology used an army of 512K units connected to a custom

Intel 80186 The Intel 80186, also known as the iAPX 186, or just 186, is a microprocessor and microcontroller introduced in 1982. It was based on the Intel 8086 and, like it, had a 16-bit external data bus multiplexed with a 20-bit address bus. The 80188 ...

-based machine to colorize numerous black-and-white films in the mid-1980s.

System software

The original 512K could accept Macintosh system software up to version 4.1; System Software 5 was possible if used with the Hard Disk 20.

Upgrades

An updated version replaced the Macintosh 512K and debuted as the Macintosh 512K ''enhanced'' in April 1986. It differed from the original 512K in that it had an 800 KB floppy disk drive and the same improved

as the Macintosh Plus. With the exception of the new model number (M0001E), they were otherwise cosmetically identical. The stock 512K could also use an 800 KB floppy disk drive as well as the

Hard Disk 20 The Macintosh Hard Disk 20 was the first hard drive developed by Apple Computer specifically for use with the Macintosh 512K. Introduced on September 17, 1985, it was part of Apple's long-awaited solution toward completing the Macintosh Office ( ...

, the first hard disk manufactured by Apple exclusively for use with the 512K, but required a special system file (not required by the 512K''e'') that loaded the improved ROM code into RAM, thus reducing the RAM available for other uses. Apple offered an upgrade kit which replaced the floppy disk drive and ROMs, essentially turning it into a 512K''e''. One further OEM upgrade replaced the logic board and the rear case entirely with that of the Macintosh Plus. The Macintosh Plus Logic Board Kit Mac512k-side

As with the original Macintosh, the 512K was designed with no slots for upgrade boards and had no hard-disk controller, so the few internal upgrades that were available for the 512K, such as General Computer's US$2,795 Hyperdrive hard drive, had to plug directly into the 68000 processor socket. Other such upgrades included "snap-on" SCSI cards and RAM upgrades of 2 MB or more.

Timeline

References

External links

Macintosh 512K technical specifications
at apple.com
Inside the Macintosh 512K
{{DEFAULTSORT:Macintosh 512k 512k 512k Computer-related introductions in 1984