Question

Why have multicore chips suddenly appeared? Are there technological factors that have paved the way? Does Moore’s law play a role here?

2. A 64-bit computer with a 400-MHz bus requires four cycles to read a 64-bit word. How much bus bandwidth does the CPU consume in the worst case, that is, assuming back-to-back reads or writes all the time?

3. Modern CPU chips have one, two, or even three levels of cache on chip. Why are multiple levels of cache needed?

Answer 1

Answer:----------------

1.
Multicore chips are integrated circuits that can contain more gates and switches to transfer more data than a single circuit. “The most common DIP [Dual Inline Packages] have 14, 16, 18, 20, 22, 24, 28, 40, 64, or 68 pins .” The greater number of pins is what makes the higher transfer rate possible. There are absolutely factors that paved the way for the advancement of multicore chips. “The Core i7 is a direct descendent of the 8088 CPU used in the original IBMPC .” This is just one example of the current technology building on and enhancing old technology, which is essentially Moore’s law. “Today, Moore’s law is often expressed as the doubling of the number of transistor’s every 18 months. Note that this is equivalent to about a 60 percent increase in transistor count per year .” As technology has grown, the need for faster computing and less battery use have increased, which has resulted in smaller chips (with smaller lines) that confirm Moore’s law.

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3.
Through caching, you can store data quickly and in a more accessibly way. The primary reasons there isn’t 1 huge cache but instead a multiple level hierarchy is due to constraints in design. When CPUs are being designed, caches are added to improve speed, but only so many caches can be added before there is overload of some sort. Cost is another factor - takes more money to add faster caches near the CPU, so instead the several cache levels will even out the cost but still improve speed and performance.