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PowerPC 601
First model of the PowerPC line as part of the AIM alliance between Apple, IBM and Motorola.
The first Macintosh models to use the PowerPC include the Power Macintosh 6100, Power Macintosh 7100 and Power Macintosh 8100.
General Information
The principal features of the PowerPC 601 microprocessor include
- full RISC processing architecture
- parallel processing units: one integer unit and one floating-point unit
- a branch manager that can usually implement branches by reloading the incoming instruction queue without using any processing time
- an internal memory management unit (MMU)
- a single built-in 32 KB cache for data and instructions
It is 132 square millimeters, or 40 percent larger than the Intel 486 chip, but it contains approximately 2.8 million transistors on four layers of metal—nearly twice the number of transistors as the 486. Yet, the 601 also contains a 32K cache, whereas the Intel 486 chip only has room for an 8K on- chip cache. In order to manufacture such a tightly packed chip, IBM used an advanced technology that was able to etch one-half micron (0.5-millionth of a meter) electrical-current pathway (called a trace width) into the silicon wafer. With such small trace widths, IBM was able to pack many more transistors on to a single chip. In addition, because the chips could be small, IBM could cut many more 601 chips without flaws from its 8-inch wafers, thus lowering the price of the chip.
The 601 processor contains a 32K on-chip cache. Instructions and data are stored on the same cache, called a unified cache scheme. Later RISC processors use a split-cache scheme that increases the CPU performance by splitting the data from the instructions into two separate 16K cache.
IBM released the 601 chips at five clock speeds: 60, 66, 80, 100, and 110 MHz. These speeds are achieved with a very low power consumption of 7 watts, further lowering the price of the chip. The 601 chip is currently used in Power Macintosh models 6100, 7100, 8100, and 7200.