Multiprocessor

A multiprocessor is a computer system with two or more processors coupled together. These processors can access uniform memory space. The unit which performs computation is known as processing element. Scientific and business community extensively uses multiprocessor embedded systems. These systems offer real time performance, low power consumption and are highly economical. Most of the battery powered devices are based on multiprocessors which give high performance at very low energy rates. An accelerator is attached to CPU buses in an embedded multiprocessor. This accelerator helps to achieve quick execution of certain key functions. They can also provide superlative performance with computational kernels that spend a great deal of time in a small section of code. Accelerators can also be used for speeding up of low latency input/output functions. The communication between CPU and accelerator is through data and control registers. Control registers allow the CPU to fine monitor the accelerator’s operation and to give the accelerator commands. Communication between CPU and accelerator is also possible via shared memory.

Multimedia

Multimedia technology is growing faster in all fields. Multimedia effectively deals the computer-controlled integration of text, graphics, drawings, still and video images, animation and audio information. For creating a text file, word processing software like Microsoft Word is used. These text files are then imported to multimedia tools to integrate with other multimedia elements. Graphic is a generic term used often to describe the pictorial representation of data. Keyboard, mouse and trackball are graphic input devices. Graphic images can be modified by using software like Adobe Photoshop, Freehand and Corel Draw. The five methods of graphics are background, 2D graphics, 3D graphics, flowcharts and charts and graphs. Vibration of air molecules which can be sensed by human ear is audio. Transmission of mechanical vibration by an elastic medium is included in audio. Video comprises of moving picture accompanied by sound.  Animation is the process of sequencing still images in rapid succession to the effect of live motion.

Bus Interface Unit (BIU)

Microprocessors are now extensively used in many applications. A microprocessor consists of a central processing unit (CPU), memory, input devices and output devices. For the interconnection of these components, buses are used. A bus is a group of parallel lines which carries digital information between digital devices in a system. There exist three varieties here – address bus, data bus and control bus. Control bus is composed of various control lines. Data bus is used for sending information between microprocessor and memory or input/output devices (bidirectional). Address bus is used for sending information from microprocessor to memory or input/output devices (unidirectional).  Memory can be either RAM or ROM. Different input/output devices used here are keyboard, mouse, modem, ADC, DAC, monitor, printer etc. Bus interface unit (BIU) handles all bus operations. BIU generally contains first in first out registers of size 6 bytes in length called queue. BIU performs prefetching of instructions from memory and then stores these instructions in the queue. This process is termed as pipelining which increases the speed of microprocessors.

Synchronous sequential circuit

Sequential and combinational logic elements are basic components of a digital system. During designing of a circuit, first step is to convert word description to algorithmic state machine chart. After this, state synthesis table is prepared. In flip-flop based circuits, these tables are used to generate design equations through Karnaugh Map. These design equations helps to develop the final circuit diagram. State machine design model is of two types- Moore model and Mealy model. If secondary outputs or memory values generates primary outputs, then the model is termed as Moore model. In Mealy model, primary inputs combine with memory elements to generate circuit output. A sequential logic circuit is a synchronous clock-triggered circuit. This can be designed in two ways. In the first model, output depends only on present state and not on input (Moore model). The other model (Mealy model) output is derived from present state as well as input. Since Mealy model requires less number of states, hardware requirement is minimum. After fixing any one of these models, next step is to fix the algorithmic state machine chart. After fixing this chart, state synthesis table has to be developed. The final stage includes usage of design equations and circuit diagram and implementation using read only memory.  

Game controllers

Computer games are becoming popular choice for time passing in the field of entertainment. Not even kids, grown up men/women too nowadays almost addicted to computer games. Any computer game requires some devices to input the data and to give commands. These devices are called as game controllers.  When a user gives input using game controllers, game program accepts it, processes it effectively and then produces output in the form of graphics and sound. The most commonly used game controllers are joystick and game pad. A joystick has a lever which the user can move to control the movement of a pointer. Joystick is the preferred choice in car racing and flying games. A game pad has a set of buttons which are known as action buttons and direction buttons. Gamepad can be controlled by using both the hands. Action buttons which are bigger in shape is used to control actions like increasing speed, stopping etc. For changing the direction, direction buttons are used. A game pad is also known as joypad or control pad.

Operating systems for computers

Some common operating systems in use are Disk Operating System (DOS), Windows-NT workstation, Windows 9x, Windows 2000 professional, Windows XP, Windows Vista, UNIX and LINUX. DOS was the lone player in this segment during initial days. Till mid 1980s, this operating system was popular. The various features of this operating system are Single user usage and batch feature. Batch feature helps to store many command in a single file which can be executed one after the other. PC DOS is the first operating system designed by IBM. But later Microsoft DOS (MS-DOS) become popular. For operation of MS-DOS, a 64K RAM is sufficient. Microsoft later released Windows-NT workstation which supports networking of computers but requires very high configuration machines. For high-end machine applications, Microsoft designed windows-95, windows-97 and windows-98. In the year 2000, Microsoft developed windows 2000 professional operating system. To work with 64-bit CPUs and to support digital media, advanced mobile computation, advanced networking and communications, Microsoft developed Windows XP and Windows Vista. UNIX and LINUX are available free of cost with multitasking features and multi-user environment.

Network topologies

A network topology is a layout of the cables, computers and other peripheral devices that are connected in a computer network. A fine classification divides network topologies into four different categories. They are star topology, ring topology, bus topology and mesh topology.  In star topology, computers and network devices are connected directly to a central server computer (hub). Any device which is connected to the hub is called as a node. In a ring topology, all the computers and network devices are connected in the form of ring. In a bus topology, computers and network devices are connected to a single cable. This cable or wire is known as bus. A network topology in which computers and network devices are interconnected with one another in the form of a mesh is called mesh topology.

Bar code readers

Bar code readers are now in common use and can be seen in shops and libraries. A bar code is composed of a series of parallel adjacent vertical lines or bars of various thicknesses. The complete information about the product can be retrieved from these vertical bars. The data coded in the form of small bars are called as bar codes. The electronic device which is used to read the coded information is called bar code reader. A bar code reader is a hand held device which scans the bar code image printed on the product and converts it into ASCII code. A computer can be used to convert ASCII code. Laser beam scanning technology is used in bar code readers. The dark lines reflect less light compared to white spaces. A scanner converts the amount of light reflected into electrical pulses which is decoded into data by a decoder. This data from decoder can be sent to computer by a cable. The advantages of these devices are economical, portable and easy to use. The main limitation is difficulty in scanning images.