The Macintosh 512K is a

personal computer A personal computer, commonly referred to as PC or computer, is a computer designed for individual use. It is typically used for tasks such as Word processor, word processing, web browser, internet browsing, email, multimedia playback, and PC ...

that was designed, manufactured and sold by

Apple Computer Apple Inc. is an American multinational corporation and technology company headquartered in Cupertino, California, in Silicon Valley. It is best known for its consumer electronics, software, and services. Founded in 1976 as Apple Computer Co ...

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

Macintosh 128K The Macintosh, later rebranded as the Macintosh 128K, is the original Mac (computer), Macintosh personal computer from Apple Inc., Apple. It is the first successful mass-market All-in-one computer, all-in-one desktop personal computer with a gr ...

. It was virtually identical to the previous

Macintosh Mac is a brand of personal computers designed and marketed by Apple Inc., Apple since 1984. The name is short for Macintosh (its official name until 1999), a reference to the McIntosh (apple), McIntosh apple. The current product lineup inclu ...

, differing primarily in the amount of built-in

random-access memory Random-access memory (RAM; ) is a form of Computer memory, electronic computer memory that can be read and changed in any order, typically used to store working Data (computing), data and machine code. A random-access memory device allows ...

. 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 Mac operating systems were developed by Apple Inc. in a succession of two major series. 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 ...

up to System 4.1. It was replaced by the Macintosh 512Ke 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 Dram, DRAM, or drams may refer to: Technology and engineering * Dram (unit), a unit of mass and volume, and an informal name for a small amount of liquor, especially whisky or whiskey * Dynamic random-access memory, a type of electronic semicondu ...

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 ...

data bus. 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 * ...

chip boosts the effective memory to 576 KB, but this is offset by the display's 22 KB

framebuffer A framebuffer (frame buffer, or sometimes framestore) is a portion of random-access memory (RAM) containing a bitmap that drives a video display. It is a memory buffer containing data representing all the pixels in a complete video frame. Mode ...

, 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 were still bundled with the Mac. Soon after this model was released, several other applications became available, including MacDraw, MacProject, Macintosh Pascal and others. In particular,

Microsoft Excel Microsoft Excel is a spreadsheet editor developed by Microsoft for Microsoft Windows, Windows, macOS, Android (operating system), Android, iOS and iPadOS. It features calculation or computation capabilities, graphing tools, pivot tables, and a ...

, 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 A switcher locomotive (American English), shunter locomotive (British English), station pilot (British English), or shifter locomotive (Pennsylvania Railroad terminology) is a locomotive used for maneuvering railway vehicles over short distanc ...

, allowing

cooperative multitasking Cooperative multitasking, also known as non-preemptive multitasking, is a computer multitasking technique in which the operating system never initiates a context switch from a running Process (computing), process to another process. Instead, in o ...

among (necessarily few) applications.

New uses

The

LaserWriter The LaserWriter is a laser printer with built-in PostScript interpreter sold by Apple, Inc. from 1985 to 1988. It was one of the first laser printers available to the mass market. In combination with WYSIWYG publishing software like PageMaker ...

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 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 Bus (computing)#Address bus, data bus multiplexed with a 20 ...

-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 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 Small Computer System Interface (SCSI, ) is a set of standards for physically connecting and transferring data between computers and peripheral devices, best known for its use with storage devices such as hard disk drives. SCSI was introduced ...

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 Products and services discontinued in 1986