Personal computer input devises

A computer uses two types of storage. A main store consisting of ROM and RAM, and backing stores which can be internal, eg hard disk, or external, eg a CD or USB flash drive.

Main store (or computer memory) is divided into Read Only Memory (ROM) and Random Access Memory (RAM).

ROM is memory that cannot be changed by a program or user. ROM retains its memory even after the computer is turned off. For example, ROM stores the instructions for the computer to start up when it is turned on again.

RAM is a fast temporary type of memory in which programs, applications and data are stored. Here are some examples of what's stored in RAM:

• the operating system
• applications
• the graphical user interface (GUI)

If a computer loses power, all data stored in its RAM is lost.

The main internal backing store is a computer's hard disk.

A hard disk stores:

• the operating system
• software applications or programs
• the majority of your data files

Hard disks spin at very high speeds (around 7,200 RPM - revolutions per minute) within a sealed unit inside the computer. Hard disks store large amounts of data - 200GB to 1TB is common in desktop computers. The data stored on a hard disk is retained until deleted, but it needs to be loaded into main store RAM before it can be used.

10. Central processing unit (CPU). Types of CPU.

A central processing unit (CPU) is the electronic device inside a computer that carries out the instructions of a computer program by performing the basic arithmetic, logical, control and input/output operations.

Performance of a computer is mainly depends on how fast you CPU works and it defines by its clock speed, digit capacity, architecture and the number of cores.

Types:

· Scalar (SISD Single Instruction Single Data) handles one data item per instruction

· Vector (SIMD Single Instruction Middle Data) handles multiple data performing one operation for this data

· MISD (Middle Instruction Single Data) - several computing devices perform various operations for the same data

· MIMD (Middle Instruction Middle Data) - several computing devices perform different operations for different data

· The conveyor on the data moving through the pipeline perform various operations at each step of the conveyor

· Systolic array data is processed in the processing elements arranged in an array

11. Central processing unit (CPU). What is inside CPU?

There is Arithmetic and logic units, Control unit Cash memory, Conveyer – the core of CPU, Model Specific Registers(MSR).

12. Input/output devices, ports and buses.

Дата добавления: 2014-12-16