Motorola’s 68K chips were losing steam, and in order to keep up with IBM PC compatibles running Intel processors, Apple got together with Motorola and IBM to define a new processor architecture, the PowerPC. Collection of the Computer History Museum, 102674143.Īpple did this the very first time in the early 1990s, with the move from Motorola 68000 (a.k.a.

Boards like this were used to test the first PowerPC chips with Davidian’s 68000 emulator. The downside is that emulated software runs slower than it would on its original processor.ġ992 prototype Apple “Smurf” card. This maintains backward compatibility for your old software while allowing new computers from the company to continue to get faster with processors using the new architecture. In other words, it translates the software you already have into native machine code for the new computer you just bought. This is a program that translates, in real time, instructions written in one ISA to a different one. The solution that Apple used each time it switched from one processor to another was to use emulation. Users aren’t going to want to buy new computers from your company if you don’t give them a way to run the software they already have. This creates a problem for computer platforms that have a large installed base of software. This is one of several reasons why Macs and PCs couldn’t easily run software written for the other, or why apps written for your iPhone don’t currently run on your Mac. Software written for that particular processor takes the form of machine code, or instructions, specific to that processor’s ISA. This is because a particular processor family defines what is called an “instruction set architecture,” or ISA.

Software written for one type of processor generally doesn’t run on another. Collection of the Computer History Museum, X1307.97, 102662157, and X224.83A.Īpple is one of only a few computer companies to successfully move its entire platform away from one processor onto another. Motorola 68000 chips used in the original 1984 Macintosh, as well as the Plus, SE, Portable, and Classic.

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