Macintosh 512K
 |
|
| Also known as | M0001W |
|---|---|
| Release date | September 10, 1984 |
| Introductory price | US$2,795 (equivalent to $6,443 in 2016) |
| Discontinued | April 14, 1986 |
| Operating system | 1.0, 1.1, 2.0, 2.1, 3.0, 3.2,3.3, 3.4, 4.0, 4.1 |
| CPU | Motorola 68000 @ 7.8338 MHz (Effectively 6 MHz) |
| Memory | 512 kB RAM (built-in) |
| Predecessor | Macintosh 128K |
| Successor |
Macintosh 512Ke Macintosh Plus |
The Macintosh 512K Personal Computer is the second of a long line of Apple Macintosh computers, and was the first update to the original Macintosh 128K. It was virtually identical to the previous Mac, differing primarily in the amount of built-in memory (RAM).
Soon after Apple introduced the Macintosh 128K they realized that the Macintosh would need more internal memory. Eight months later, on September 10, 1984, Apple introduced the Macintosh 512K. With quadrupled RAM, the Macintosh was able to become a more business-capable computer and gained the ability to run more software. The Mac 512K originally shipped with Macintosh System 1.1 but was able to run Macintosh System 1.0 all the way up to System 4.1. When the Macintosh Plus was introduced in 1986, the Macintosh 512K was discontinued on April 14, 1986. All support for the Mac 512K was discontinued on September 1, 1998.
Like the 128K Macintosh before it, the 512K contained a Motorola 68000 connected to a 512 kB DRAM by a 16-bit data bus. Though the memory had been quadrupled, it could not be upgraded. This large increase earned it the nickname Fat Mac. A 64 kB ROM 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 re-badged Macintosh 128K (previously just called the Macintosh), which streamlined manufacturing. The resolution of the display was the same, at 512x342.
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, 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 among (necessarily few) applications.
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