Книга: Introduction to Microprocessors and Microcontrollers

13. The PowerPC

13. The PowerPC

Intel was producing a series of CISC microprocessors and, together with Microsoft, was in a position to dominate the market. Being increasingly squeezed out was the traditional king of computers, IBM, which, at one time, produced more computers that all other manufacturers combined. Big Blue as IBM was called, on account of their logo and the blue suits worn by their army of salesmen, laid down the standard design for the computer that now eclipses all others designs in the world.

As long ago as the mid-1970s IBM had developed a RISC microprocessor but it didn’t really make it in the market place. RISC did not ‘come of age’ until Acorn produced the ARM 2 and 3 microprocessors for their Archimedes microcomputer, but this too, failed to muscle its way into the market as it made little attempt to make it compatible with Intel code. Acorn, at that time, was introducing the Archimedes as a replacement for the much-loved BBC microcomputer. By 1990, it was apparent that the terrible twins, Microsoft and Intel, would take over the world if no one fought back.

As it happens, this was the very year in which a fledgling company called ‘AMD’ was hatched to grow over the years to become a persistent irritant to Intel. As yet, Microsoft still rules the world but there is a system called Linux that may, one day, become troublesome.

Meanwhile, an alliance was formed between IBM, Motorola and Apple Computers. To this alliance IBM brought their POWER microprocessor (Performance Optimized With Enhanced RISC). This was the successor to the earlier 801 RISC microprocessor and was chosen because it was a RISC microprocessor and already had software developed. Motorola would build the chip and Apple would bring its computer operating system, which was light years ahead of the Microsoft equivalent at that time. The new family of microprocessors was to be called the PowerPC series.

The designers took great care to make it attractive to software companies by being careful to address the problem of future development. They distinguished between the overall architectural features that will stay the same throughout the series, rather than how these features will actually be implemented. This allows the programmers to know which parts they can rely on to be consistent and which bits are likely to change. For example, they designed the system for 64-bit operation even though only 32 bits were to be used in the early devices.

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