Organization of a Microcomputer : Hardware Organization Part-1

A basic PC system has a number of major hardware elements. Figure 4.2 shows the simplified block diagram of a microcomputer. These elements are contained in the system unit of the microcomputer.

 Procassor :

In most PCs this is an Intel Pentium microprocessor or one of the intel compatible processors available from several companies.

Input and Output Devices :

Input devices include keyboard, mouse, scanners, CD-ROM driver, bar code, readers etc. The most common output devices are printers and display monitors. These devices are attached to the microprocessor through posts that attach to the systemunits microprocessor buses.

Memory Devices :

They are used to save programs and data.

Buses :
They connect the microprocessor to its memory and to the adapters that enable connection to other devices through their posts or expension slots. The buses inter connect the hardware components of the microcomputer. The systems buses define system performance and adapter compatibility.

Adapters :

They enable the microprocessor to communicate with and control I/O or storage devices. The adapters are a set of hardware circuitry that attach to the systems buses and contest each bus to an interface port supporting the attainent of specific I/O device. For example, a serial post adapter attaches to a bus and it has a COM post where a modem can be attached. The adapter is thus the bridge between the microcomputer bus the device that offer to be attached to the microcomputer. Adapters may be "integrated" on the motherboard or adapter boards that plug into expansion slots.

Ports :
The posts of the adapters support the attachment of I/O devices.

Expansion Slots :
They are physical connectors where adapters can attach to the buses so that the microcomputer can be configured with a variety of adapters. Expansion slots permit easy expansion or upgrading of a system with new I/O devices and memory.

Low-Speed Storage Devices :
They store data and programs for long term. This includes nonvolatile magnetic media and optical media storage such as hard drivers, CD ROM, and floppy disks.


Chronological Events of Computer Processor

Hellow, how are you ? I gonna to now chronological events of computer processor. So just see it and know knowledge.

1) 1971- First Microprocessor (Intel 4004)
2)1972- First 8 bit Microprocessor ( Intel 8008)
3) 1975- First Microcomputer ( Altair 8800)
4) 1977- Apple II Computer, Microsoft Corporation Founded by Bill Gates and Paul Allen
5) 1978- Intel 16 bit Microprocessor ( Intel 8086)
6) 1979- Motorola 16 bit Microprocessor ( M 68000)
7) 1981- IBM PC Introduced
8) 1983- IBM PC XT
9) 1984- Apple Macintosh
10) 1988- First Computer Virus
11) 1990- Microsoft Introduced Windows 3.0
12) 1992- First 64 bit RISC Microprocessor (Alpha)
13) 1993- Intel Pentium Microprocessor
14) 1994- 300 MHz, 64 bit RISC Processor
15) 1996- Intel PentiumPro Microprocessor
16) 1997- 500 MHz Alpha 2114 RISC Processor (Alpha)
17) 1998- Intel Pentium II
18) 1999- Intel Pentium III
19) 2000- Intel Pentium IV


Servers and Disk Arrays

Servers and disk arrays are the network configurations of personal computers. Networks enable multiple computers and their users to share processing power, disk storage, printers and other peripheral devices.

Most of the computers mentioned before can function as a server or as the controller for a disk array. Personal computers are evolving in such a way the differentiation between client and servers are diminishing. A server is usually a high end PC having a lot of memory and several large disks for storage and is dedicated to managing network traffic, storing common programs or data for users across the network, or directing communications via telephonne lines outside the local network.

A disk array is a special kind of server that uses a large portion of its processor power simply to manage I/O for a collection of disk drivers. A regular PC may contain one or two hard drivers with several GBs of storage, whereas a disk array may contain many times more storage space for programs and data.


PC and PC Clones

Microcomputers come in a wide variety of designs. They are known as " personal computers" and are relatively small, relatively inexpensive, and are designed primarily for use by one person at a time. However there are significant exceptions to this powerful personal computers are used as data or application servers in a networking environment or for huge data processing applications.

The term "PC" generally contrasts computers based on the hotel family of micro-processors and compatibles with Apple computers Macintosh, and other non-Intel systems. This started with IBM original Personal Computer, which was based on the Intel 8088 processor and labeled " The PC" when it reached the market in the early 1980s.

Most of the personal computers sold today do not come from IBM at all. Most are designed, built, and sold by a number of manufacturers who offer a wife range of PCs for business, education and home use. These machines are called "clones" because they were made to look, feel and work like an IBM PC. The name clone seems to stay with these machines, though manufacturers have moved in their own directions.


What is Computer Programs

Programs tell a computer what to do. There are two different kinds of programs: systems programs and applications programs. All programs accomplish some kind of work. Systems programs help operate the computer itself; the goods systems of a computer are controlled by systems programs. An applications program carrier out a task for the user. In fact, application programs get users work done, and systems programs help a computer manage itself.

A few of the systems programs, that a PC needs to manage its operating, are permanently built into it. These are called firmware, because they are permanently stored in read only memory. These programs do the most fundamental supervisory and support work, such as providing essential services that all the application programs use. These service programs are called the Basic Input/Output system (BIOS).

Other systems programs built on the foundation created by the BIOS provide a higher level of support services. Operating systems, such as DOS and windows are examples of there higher-level systems programs.


What is I/O Devices

In general, the I/O devices are a bridge between a user and a microcomputer. A microcomputer gets what the user types on the keyboard, the user sees what the computer writes on the printer or displays on the screen.

The disk storage is a special category of I/O that is intended for a computers own use. Information on a disk can be read and written only by the computer and it can not be read or written by users.

The microprocessor and the memory make up a closed world and the I/O devices open the world to the users. The computer communicates through I/O devices open the world to the users. The computer communicates through I/O devices. These devices include keyboard, display screen, mouse, printer, telephone line connected to the computer, and any other channels of communication into or out of the computer.


What is Computer Memory

The processor finds programs and data from memory when it does its assigned task. The memory is the place where every thing is kept. The microcomputers memory is just a temporary space like a chalkboard where the computer scribbler while work is being done. Unlike human memories, the computers memory is not a permanent repository. The computers memory simply provides a place where computing can happen.

The processor makes a vital distinction between programs and data. But to the computers memory there is no difference between programs and data. It is like a piece of paper that neither knows nor cases what one writes on it. It is the same with the microcomputers memory. Only the processor recognizes the difference between program and data.

Anything can be written on the memory, and the writing can be changed by writing over it. Unlike a chalkboard, the computers memory doesnt have to be asaped before something new can written to it, the act of writing automatically eraser what was in the memory before. Reading information from the memory is simple and straightforward as reading any thing written on paper. Both the processor and the I/O devices have the capability to read and write data from and to the main memory.


What is Processor

The processor executes or stop a program. The processor must have the capability to read and write information in the computers memory. Both the program instructions that the processor carriers not and the data on which the processor works are stored in the memory. The processor must recognize and execute a series of commands or instructions provided by programs. The processor must tell other parts of the computer what to do. So that, the processor can carry out the operations of the microcomputer.


Microcomputer Components

The five key parts of a computer are :
1) Processor
2) Memory
3) Input/Output devices
4) disk storage
5) programs Figure

4.1 shows the basic components of a microcomputer and how they fit together. Before the advent of integrated circuits, individual portions of computers were housed on separate boards or even in separate units made up of many boards. Today, the majority of the circuits of the microcomputer are housed on a single printed circuit called the system board or motherboard. The usual components on the motherboard include the main processor and its support circuits, memory, I/O interface and a cup system which enables the CPU to talk to other components that are not integrated with the motherboard. The processor is the brain of the microcomputer. It executes instructions and programs. The processor performs arithmetic and simple logical operations. In a microcomputer like PC, the main processor is a microprocessor. Memory is the microcomputer workplace.

The size of a microcomputers memory sets a practical limit on the kinds of work that can be undertaken. The variety of tools that can be used at any time is largely determined by the size of the memory of the microcomputer. Microcomputers are rated by the amount of memory they have.

The computer takes in and sends out date through input/output devices. They include what we type on the keyboard and what the computer shows on the display screen or prints on the printer. The I/O device. It is the computer reference library, filing cabinet, and toolbox all in one. The computer keeps data in the disk when they are not in use in the computers memory. The disks are the most practical and important medium for storing data.

Programs bring a computer to life, make it go, and turn it into a powerful working tool. Programs tell the computer what to do, when to do and how to do.


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