Laboratory work № 4 The architecture of modern computers.
Any PC should be considered as some hardware-software complex, providing realization of some class of algorithms of processing of the information. During the process
all its components cooperate with each other to special way. Thus ways of interaction can be divided into following levels:
1. The lowest level: at level of electric signals.
2. The highest level: at program level – interaction of PC knots at Program modules level.
3. Functional level of each separate knot: function and its realization by software -hardware (this concept also is known as the term "Architecture").
The architecture is known as set of properties and characteristics of a computer (system) that is considered by user.
At the heart of any COMPUTER two fundamental concepts of computer facilities lie:
1. Concept of algorithm.
2. A programmed control principle.
Algorithm – some unequivocally certain sequence of actions, consisting of formally determined operations over the initial data and leading to the solution for final number of steps.
Properties of algorithms:
1. Step-type behavior of algorithm (action is carried out on steps, and the information is discrete).
2. Determinacy (how many time the same algorithm wouldn't be realized for the same data on same computer the result will be same).
3. Mass character – algorithm «solves a problem» for the various data from the admissible sets and always gives a correct result).
A program is an algorithm description in any language.
The programmed control principle (PCP) has been formulated by the Hungarian mathematician and physicists John Fon Neumann, with the assistance of Goltstan and Berts in 1946.
PCP includes some architecture-functional principles:
1) any algorithm is represented in the form of sequence of operating words – commands. Each separate command defines a simple (individual) step of Information transformations.
2) the conditional transition principle. Depending on the received intermediate data during calculations the automatic transition to this or that part of program is possible.
3) the stored program principle. Commands are represented to the COMPUTER in same coded form, as well as any data, and also is stored in same part of RAM. It means that if to consider contents of memory without any command it is impossible to distinguish commands and the data.
Hence, any commands can be processed essentially as the data
4) the binary coding principle.
5) the memory hierarchical principle.
Classification of computers
According to Size.
According to Technology.
According to Purpose.
According operating modes
According the structural organization
According to size
• Supercomputers
• Mainframe Computers
• Minicomputers
• Workstations
• Microcomputers, or Personal Computers
Supercomputers : are widely used in scientific applications such as aerodynamic design simulation, processing of geological data.
• Supercomputers are the most powerful computers. They are used for problems requiring complex calculations.
• Because of their size and expense, supercomputers are relatively rare.
• Supercomputers are used by universities, government agencies, and large businesses.
Mainframe Computers: are usually slower, less powerful and less expensive than supercomputers. A technique that allows many people at terminals, to access the same computer at one time is called time sharing. Mainframes are used by banks and many business to update inventory etc.
• Mainframe computers can support hundreds or thousands of users, handling massive amounts of input, output, and storage.
• Mainframe computers are used in large organizations where many users need access to shared data and programs.
• Mainframes are also used as e-commerce servers, handling transactions over the Internet.
Minicomputers: are smaller than mainframe, general purpose computers, and give computing power without adding the prohibitive expenses associated with larger systems. It is generally easier to use.
• Minicomputers usually have multiple terminals.
• Minicomputers may be used as network servers and Internet servers.
Workstations
• Workstations are powerful single-user computers.
• Workstations are used for tasks that require a great deal of number-crunching power, such as product design and computer animation.
• Workstations are often used as network and Internet servers.
Microcomputers, or Personal Computers : is the smallest, least expensive of all the computers. Micro computers have smallest memory and less power, are physically smaller and permit fewer peripherals to be attached.
• Microcomputers are more commonly known as personal computers. The term “PC” is applied to IBM-PCs or compatible computers.
• Desktop computers are the most common type of PC.
• Notebook (laptop) computers are used by people who need the power of a desktop system, but also portability.
• Handheld PCs (such as PDAs) lack the power of a desktop or notebook PC, but offer features for users who need limited functions and small size.
Personal Computers(PC)
Desk Top
Lap Top
Palm Top
PDA
According to Technology
• Analog Computers
• Digital Computers
• Hydride Computers
Analog Computers:- These computers recognize data as a continuous measurement of a physical property ( voltage, pressure, speed and temperature).
Example: Automobile speedometer
Digital Computers:- These are high speed programmable electronic devices that perform mathematical calculations, compare values and store results. They recognize data by counting discrete signal representing either a high or low voltage state of electricity.
Hybrid Computers:-A computer that processes both analog and digital data.
According to Purpose
General purpose Computers
Special Computers
General purpose Computers
A ‘General Purpose Computer’ is a machine that is capable of carrying out some general data processing under program control.
Refers to computers that follow instructions, thus virtually all computers from micro to mainframe are general purpose. Even computers in toys, games and single-function devices follow instructions in their built-in program.
Special purpose Computers
A computer that is designed to operate on a restricted class of problems.
According operating modes
– One-program COMPUTERS;
– Multiprogram COMPUTERS (these COMPUTERS should have the large RAM, time-control facilities, input-output tools, tools that allows to exclude influence of programs to each other).
– The COMPUTER for construction of machine and multiprocessing computing systems (in addition to multiprogram COMPUTERS should realize functions of exchange data between the COMPUTER).
– The COMPUTER for work in real-time systems, for example, for technical process management (process of glassmaking) or object management (Autopilot). Here high demands are made to possibility of fast processing of the large size of data files from the various external sources.
According the structural organization
– Uniprocessor;
– Multiprocessor (the main destination to take high efficiency).
The four classifications defined by Flynn are based upon the number of concurrent instruction (or control) and data streams available in the architecture:
Single Instruction, Single Data stream (SISD)
A sequential computer which exploits no parallelism in either the instruction or data streams. Examples of SISD architecture are the traditional uniprocessor machines like a PC(currently manufactured PC's have multiple processors) or old mainframes.
Single Instruction, Multiple Data streams (SIMD)
A computer which exploits multiple data streams against a single instruction stream to perform operations which may be naturally parallelized. For example, an array processor orGPU.
Multiple Instruction, Single Data stream (MISD)
Multiple instructions operate on a single data stream. Uncommon architecture which is generally used for fault tolerance. Heterogeneous systems operate on the same data stream and must agree on the result. Examples include the Space Shuttle flight control computer.
Multiple Instruction, Multiple Data streams (MIMD)
Multiple autonomous processors simultaneously executing different instructions on different data. Distributed systems are generally recognized to be MIMD architectures; either exploiting a single shared memory space or a distributed memory space.