![]() At the time, a key concept in minis was the concept of an orthogonal instruction set, in which every operation was allowed to work on any sort of data. The new system was influenced by the PDP-11, the most popular minicomputer design of the era. The team decided to abandon an attempt at backward compatibility with the 6800, as they felt the 8-bit designs were too limited to be the basis for new designs. They wanted the design to not only win back microcomputer vendors like Apple Computer and Tandy, but also minicomputer companies like NCR and AT&T. The performance goal was set at 1 million instructions per second (MIPS). Gunter began forming his team in January 1977. MACSS Ĭrook formed the Motorola Advanced Computer System on Silicon (MACSS) project to build the design and hired Tom Gunter to be its principal architect. Crook had decided on this approach by the end of 1976. Another 16-bit would not do, their design would have to be bigger, and that meant having some 32-bit features. Crook decided that they would attack the high-end of the market with the most powerful processor on the market. In order to compete, they set themselves the goal of being two times as powerful at the same cost, or one-half the cost with the same performance. Motorola knew that if they launched a product similar to the 8086, within 10% of its capabilities, Intel would kill them in the market. These would use new design techniques that would eliminate the problems seen in earlier 16-bit systems. They were aware that Intel was working on a 16-bit extension of their 8080 series, which would emerge as the Intel 8086, and had heard rumors of a 16-bit Zilog Z80, which became the Z8000. With the sales prospects for the 6800 dimming, but still cash-flush from the engine control sales, in late 1976 Colin Crook, Operations Manager, began considering how to successfully win future sales. Based on the semiconductor manufacturing processes of the era, these were often multi-chip solutions like the National Semiconductor IMP-16, or the single-chip PACE that had issues with speed. These were generally modeled on minicomputer platforms like the Data General Nova or PDP-8. Moving to 16-bit īy the time the 6800 was introduced a small number of 16-bit designs had come to market. By late 1976, the sales book was flat and the division was only saved by a project for General Motors that turned into a huge product line for engine control and other tasks. Although a capable design, it was eclipsed by more powerful designs, such as the Zilog Z80, and less expensive designs, such as the MOS Technology 6502. The company set itself the goal of selling 25,000 units by September 1976, a goal they did meet. Motorola's first widely produced microprocessor was the 6800, introduced in early 1974 and available in quantity late that year. The original 68k is generally software forward-compatible with the rest of the line despite being limited to a 16-bit wide external bus. Later processors in the Motorola 68000 series, beginning with the Motorola 68020, use full 32-bit ALUs and have full 32-bit address and data buses, speeding up 32-bit operations and allowing full 32-bit addressing rather than the 24-bit addressing of the 68000 and Motorola 68010 or the 31-bit addressing of the Motorola 68012. The 1988 Sega Genesis/Mega Drive console is powered by a 68000. It was widely used in a new generation of personal computers with graphical user interfaces, including the Macintosh 128K, Amiga, Atari ST, and X68000. For this reason, Motorola termed it a 16/32-bit processor.Īs one of the first widely available processors with a 32-bit instruction set, large unsegmented address space, and relatively high speed for the era, the 68k was a popular design through the 1980s. Internally, it uses a 16-bit data arithmetic logic unit (ALU) and two more 16-bit ALUs used mostly for addresses, and has a 16-bit external data bus. The address bus is 24 bits and does not use memory segmentation, which made it easier to program for. ![]() ![]() The design implements a 32-bit instruction set, with 32-bit registers and a 16-bit internal data bus. ![]() 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.
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