Transistor Density
As processors become newer and more advanced, the number and density of the transistors inside increases. The chip needs to perform millions of calculations and synchronize between the transistors. As new speed and more complex processing techniques come to processors, more processors are needed. And as the number of transistors increase, the size and density of each transitor needs to reduce in order keep the processor not only of a human size, but also capable of being powered. Transistors have become VERY small and are also increasingly tightly packed together. Older chips had 1 micron between transistors. Although this isn’t much, it is a lot in the world of CPU’s. Today’s modern chips have distances of about 0.18 to 0.13 micron between transistors. The Pentium IV, for example, contains 55 million transistors in its core.
Instruction Sets
An insturction set is simply a set of instructions that a processor is capable of understanding and executing. All processors have their basic instruction set for executing day-to-day code. But, worthy of mention here is the more proprietary instruction sets that have been added to processors in order to increase their capability in certain areas, increase speed, and generally be used as a marketing gimmick.
Multimedia Extension (MMX) Technology is an instruction set built in to the later Pentiums and virtually all later chips. MMX is an extension off the regular x86 instruction set that allows bytes of data, or instructions, to be packed together into a single register and operated on as one set of data, therefore reducing the amount of work that the chip has to do and allowing it to do more. MMX is thought to be mainly an improvement in multimedia performance, but this is not necessarily true. Its just that these types of applications stand to benefit most from this type of data handling. Such applications need to be specially designed to take advantage of MMX, and many vendors are releasing MMX enhanced software.
How it Works (The following information is provided by Intel) :
The Pentium processor with MMX technology has three primary architectural design enhancements.
- New Instructions Intel engineers have added 57 powerful new instructions specifically designed to manipulate and process video, audio and graphical data efficiently. These instructions are oriented to the highly parallel, repetitive sequences often found in multimedia operations.
- SIMD Today’s multimedia and communication applications often use repetitive loops that, while occupying 10 percent or less of the overall application code, can account for up to 90 percent of the execution time. A process called Single Instruction Multiple Data (SIMD) enables one instruction to perform the same function on multiple pieces of data. It allows the chip to reduce compute-intensive loops common with video, audio, graphics and animation. As an analogy, consider a drill sergeant telling an entire platoon, “About face,” rather than commanding each individual soldier one at a time.
- More Cache Intel has doubled on-chip cache size to 32 KB on the Intel Pentium processor with MMX technology. Now, more instructions and data can be stored on the chip, reducing the number of times the processor has to access slower, off-chip memory areas for information.
Intel, with the release of the Pentium III, introduced the SSE instruction set. Also called MMX2, it was basically an extension off the original MMX set, adding 70 new instructions to the set designed to increase performance in 3D apps.
3DNow! is another instruction set designed by AMD that was originally set to compete with Intel’s MMX. Now a standard like MMX, the instruction set started out with 21 new instructions designed to help with integer calculations and floating point operations.
Conclusion
Hopefully this has given you some useful information. Processors are constantly evolving, so things are always changing. But, the field of processor design is a fascinating one.
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