CPU Processor - Central Processing Unit
A central processing unit (CPU), or sometimes simply processor, is the key component in a digital computer capable of executing a program. It interprets computer program instructions and processes data. CPUs provide the fundamental digital computer trait of programmability, and are one of the necessary components found in computers of any era, along with memory and input/output facilities. A CPU that is manufactured as a single integrated circuit is usually known as a microprocessor. Beginning in the mid-1970s, microprocessors of ever-increasing complexity and power gradually supplanted other designs, and today the term "CPU" is usually applied to some type of microprocessor.
Memory or RAM
Next most critical element of a processing hardware is RAM, often referred to as "primary storage" or "main memory". Random Access Memory (RAM) receives and temporarily stores data and program instructions from the CPU This data bank communicates with the CPU, constantly exchanging information and constantly changing as long as the computer is on
RAM is an active, electronic state. When the power is on, RAM retains data. When the computer is turned off, all data in RAM is erased unless you have saved it to some mass storage device. Each time the computer boots, the computer goes through it's startup routine and lastly loads operating system instructions into RAM. Random Access Memory (RAM) is the workhorse behind the performance of your computer. Working as a foot soldier for your processor, RAM temporarily stores information from your operating system, applications, and data in current use. This gives your processor easy access to the critical information that makes your programs run. The amount of RAM you have determines how many programs can be executed at one time and how much data can be readily available to a program. It also determines how quickly your applications perform and how many applications you can easily toggle between at one time. Simply put, the more RAM you have, the more programs you can run smoothly and simultaneously.
To determine how much RAM you need, factor in the demands of the applications you want to run simultaneously as well as the operating system (512 MB of RAM is recommended by Microsoft as minimum for operation of Windows) Then keep in mind that you'll inevitably add new applications and create new files, and add accordingly.
RAM: (Random Access Memory):
Types of RAM:
*DRAM (Dynamic RAM) This is the most common type of computer memory. DRAM needs refreshing and is refreshed hundreds of times each second in order to retain data. During recharging it cannot be accessed by the CPS
*SRAM (Static RAM) SRAM is approximately 5 times faster (and twice as expensive, as DRAM). It does not have to be constantly refreshed. Because of its lower cost and smaller size, DRAM is preferred for the main memory, while SRAM is used primarily for cache memory.
*SDRAM (synchronous dynamic RAM) is the standard memory offering in the PC industry and is faster than DRAM because it's synchronized to the system clock. . It is designed for mainstream home and business applications, email, and basic audio and video streaming. It provides single-channel memory and is available on our mainstream and value desktop system.
*DDR SDRAM (double data rate synchronous dynamic RAM) takes all the features of ordinary SDRAM and increases the frequency bandwidth to improve system performance and speed.
*RDRAM (Rambus dynamic RAM) is able to load a new stream of data before the previous stream has completed, resulting in faster access speeds. The RDRAM memory features dual-channel processing which doubles data throughput to further enhance performance. This type of memory is optimized for high-end multimedia tasks involving video and audio. Dual Channel RDRAM is shipped on our performance desktop systems powered by Pentium 4 processors
*VRAM: Memory designed for storing the image to be displayed.
*CACHE RAM is a small block of high-speed memory located between the Processor and main memory and is used to store frequently requested data and instructions. When the processor requests data, it will check in the cache first
The hierarchical arrangement of memory storage in current computer architectures is called the memory hierarchy. It is designed to take advantage of memory locality in computer programs. Each level of the hierarchy is of higher speed and lower latency, and is of smaller size, than lower levels.
The memory hierarchy in most computers is as follows:
*Processor registers – fastest possible access (usually 1 CPU cycle), only hundreds of bytes in size
*Level 1 (L1) cache – often accessed in just a few cycles, usually tens of kilobytes
*Level 2 (L2) cache – higher latency than L1 by 2× to 10×, often 512 KiB or more
*Level 3 (L3) cache – higher latency than L2, often several MB
*Main memory (DRAM) – may take hundreds of cycles, but can be multiple gigabytes. Access times may not be uniform.
