Improving the CPU quality is closely related to electronic technology improvement. According to industry research, there will be new type of CPU or PC launch to market every 3 to 4 years time. Here are a few methods they have used to improve the CPU performance

1. CPU internal Clock speed.
2. Data Bus width
3. L1 Cache memory
4. L2 Cache memory
5. MMX technology
6. 3Dnow! Technology
7. Others

1. CPU internal Clock Speed

This is very obvious and everybody know that faster CPU internal Clock speed (or) CPU speed make better CPU performance. The Clock Speed is increased from 8Mz ( Intel 8086 CPU) to 500Mhz (Intel Pentium-III CPU) gradually whenever electronic technology is available to do so.

 

2. Data Bus width

Data Bus width (internal & external data bus width) is one of the important factor to improve the CPU performance. Basically, smaller Data Bus width takes more time to read/transfer data from one place to another. The external Data Bus width of very first CPU (Intel 8086 CPU) was only 8-bits. Then next model (Intel 80386 CPU) used 16-bits external Data Bus width. After some time later newer Intel 80386 CPU and Intel 80486 CPU used 32-bits Data Bus size. Latest Pentium/Pentium-II series CPUs are using 64-bits external Data Bus size which performance is obviously better than old CPUs.

 

3. L1 Cache memory

The purpose of cache memory is to enable the processor to run in a constant state of flux. Whenever the processor is made to wait on data or instructions will slowdown the overall computation. Memory caching is effective because most programs access the same data or instructions over and over. By keeping as much of this information as possible in cache, the computer avoids accessing the slower system memory. When data is read from, or written to, main memory a copy is also saved in the cache, along with the associated main memory address. The cache monitors addresses of subsequent reads to see if the required data is already in the cache. If it is (a cache hit) then it is returned immediately and the main memory read is aborted (or not started). If the data is not cached (a cache miss) then it is fetched from main memory (main memory is the RAM memory on motherboard) and also saved in the cache. The cache is built from faster memory chips than main memory, so a cache hit takes much less time to complete than a normal memory access.

Level 1 Cache is typically 8K to 64K in size. It is built directly into the CPU and is extremely effective because it operates at the same speed as the processor. Due to this speed and the highly-integrated design, large L1 caches produce very large performance gains. Level l cache uses very fast type SRAM memory, which are built into the architecture of microprocessors. Such internal caches are expensive and often called Primary Cache memory (or) L1 caches.

The Intel 80486 microprocessor, for example, contains an 8K memory cache, and the Pentium and Pentium-Pro has a 16K L1 Cache. Pentium-MMX, Pentium-II, Celeron and Pentium-III contains 32K L1 Cache memory.

AMD K5 CPU has 24K and AMD K6 CPU has 64K L1 cache.

Cyrix 6x86/ 6x86MX CPU contain 16K and CyrixM-II CPU has 64K L1 cache.

 

4. L2 Cache memory

Level 2 Cache is located externally to the CPU. It is generally 256K to 1024K in size. "Conventional" L2 caches generally run at speeds which are substantially slower than the CPUs they service, yet they are significantly faster than the computer's main System Memory. L2 cache improves system-level performance by improving the CPU’s memory read and write performance, as well as decreasing the system bus utilization. A larger, more efficient L2 cache will result in less processor read requirements to main memory which is implemented in slower DRAM thus reducing the number of times the processor needs to access the bus.

Start from Pentium-Pro CPU, Intel coupled 256K/512K L2 Cache memory together with CPU and let them run at full speed of processor. All Intel Pentium-II CPU has 512K L2 cache memory except Celeron with 128K only.

AMD and Cyrix CPUs do not contain L2 cache within CPU module. These CPUs look for L2 on motherboard and size is usually 256K or 512K depend on motherboard manufacturer.

 

5. MMX Technology

1. 57 new microprocessor instructions have been added that are designed to handle video, audio, and graphical data more efficiently.
2. A new process, Single Instruction Multiple Data (SIMD), makes it possible for one instruction to perform the same operation on multiple data items.
3. The memory cache on the microprocessor has increased to 32 thousand bytes, meaning fewer accesses to memory that is off the microprocessor.

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