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IT Tools and Business System - 2. Computer Organization
2. Computer Organization
Central Processing Unit - Processor Speed, Cache, Memory- RAM, ROM, Booting, Memory – Secondary Storage Devices: Floppy and Hard Disks, Optical Disks CD-ROM, DVD, Mass Storage Devices: USB thumb drive. Managing disk Partitions, File System, Input Devices - Keyboard, Mouse, joystick, Scanner, web cam, Output Devices- Monitors, Printers – Dot matrix, inkjet, laser, Multimedia- What is Multimedia, Text, Graphics, Animation, Audio, Images, Video, Names of common multimedia file formats, Computer Software- Relationship between Hardware and Software; System Software, Application Software, Compiler, names of some high level languages, free domain software.
Central Processing Unit
A central processing unit (CPU) is the electronic circuitry within a computer that carries out the instructions of a computer program by performing the basic arithmetic, logical, control and input/output operations specified by the instructions. Principal components of a CPU include the arithmetic logic unit (ALU), which performs arithmetic and logical operations, and the control unit (CU), which fetches instructions from memory and decodes and executes them, calling on the services of the ALU when necessary. Fetch, decode and execute is the most basic function of the CPU which means getting input, processing it and then executing the program (output). There are mainly two different types of CPUs used in modern desktop systems: 32-bit CPUs and 64-bit CPUs. The instructions in a 32-bit CPU are good at handling data that is 32 bits in size (most instructions "think" in 32 bits in a 32-bit CPU). Likewise, a 64-bit CPU is good at handling data that is 64 bits in size (and is often good at handling 32-bit data too). The size of data that a CPU handles best is often called the word size of the CPU. Many older CPUs from the 70s, 80s and early 90s (and some modern small CPUs) have an 8-bit or 16-bit word size. Intel atom, Pentium, Xeon, Core I series, AMD, ARM etc are the examples of CPU.
A computer's processor speed describes the maximum number of calculations per second the processor can perform, and is given in megahertz (MHz) or gigahertz (GHz). Generally, the larger the number, the faster and more powerful the processor.
Cache
Cache is a component that transparently stores data so that future requests for that data can be served faster. The data that is stored within a cache might be values that have been computed earlier or duplicates of original values that are stored elsewhere. If requested data is contained in the cache (cache hit), this request can be served by simply reading the cache, which is comparatively faster. Otherwise (cache miss), the data has to be recomputed or fetched from its original storage location, which is comparatively slower. Hence, the greater the number of requests that can be served from the cache, the faster the overall system performance becomes. L1, L2, L3 are different standards of cache.
Memory
Memory refers to the physical devices used to store programs (sequences of instructions) or data (e.g. program state information) on a temporary or permanent basis for use in a computer or other digital electronic device.
Primary memory – Primary memory is the memory that can be directly accessed by the processor. Primary memory holds only those data and instructions on which computer is currently working. It has limited capacity and data is lost when power is switched off. It is generally made up of semiconductor device. These memories are not as fast as registers. The data and instruction required to be processed reside in main memory. It is divided into two subcategories RAM and ROM.
RAM – Acronym for Random Access Memory or sometimes spoken as ‘memory’ is a vital part of a computer system. Whenever the program is executed, RAM works as the shelter. Since it is volatile, the data is lost after power failure or shutdown. To save the data, data must be transferred to secondary storage or memory. DRAM and SRAM are the types of RAM.
Read-only memory (ROM) - ~ is a class of storage medium used in computers and other electronic devices. Data stored in ROM can only be modified slowly, with difficulty, or not at all, so it is mainly used to distribute firmware (software that is very closely tied to specific hardware, and unlikely to need frequent updates). Data stored in ROM are non-volatile. PROM, EPROM, EEPROM are the examples of different ROMs.
Secondary memory/storage - Primary memory is the memory that cannot be directly accessed by the processor. This type of memory is also known as external memory or non-volatile. It is slower than main memory. These are used for storing data/Information permanently. CPU directly does not access these memories instead they are accessed via input-output routines. Contents of secondary memories are first transferred to main memory, and then CPU can access it. For example : Floppy and Hard Disks, Opt