APPLICATION OF COMPUTER FOR DATA ANALYSIS

Computer are widely used for data analysis.There is a special software called spreadsheet program for data analysis.Data are entered into rows and columns.Using spreadsheet program one can tabulate results,calculate number of students in first class,second class,failed student,percentage of students in different classes,list of failure students,average marks etc.

One can prepare product sales,profit,investment computation for an organization using spreadsheet programs. Year wise numbers of unit sold,price per unit,production cost,selling cost etc.are entered into the spreadsheet.Revenue are calculated from the units sold and per unit price.Total expenditure is the sum of production cost and the selling cost.Profit is equal to production cost minus total expenditure.

Similarly,any kind of computation for data entered in the tabulated form can be made using computers with spreadsheet program.

Computers are widely used for statistical data analysis.Statistical packages are available for such purposes.They can accept data from other files and sort,merge and manipulated data as needed.

Spreadsheet template are available for various kinds of data analysis.The user has only to enter data and get the desired results.

The spreadsheet programs are also used for accounts,sale analysis,inventory control,financial aspect of business,preparation of budgets etc. 

OPTICRAM Cameras

An OPTICRAM camera contain a 64 KB dynamic RAM.The cover of the dynamic RAM is made of glass instead of metal or plastic.An image of an object is directly focused onto the glass surface of dynamic RAM by the lens on the front of the camera.The dynamic RAM contains 65,536(64 KB) memory cells.These cells are divided into two sections.Each section is a matrix of 128 X 256 cells.Each cell functions as a pixel.

In a dynamic RAM 0 and 1 are stored as charge on tiny capacitors.As the charge gradually change due to leakage,a dynamic RAM has to be be refreshed periodically.If light falls on a dynamic RAM cell,the stored charge on the tiny capacitor changes at a faster rate as compared to the usual condition when there is no light falling on the memory cells.A dynamic RAM can be used as an image sensor.For this purpose all memory cells,are first charged to logic 1 level.After certain predetermined interval of time the logic level has changed from 1 to 0 represents a light spot.The logic level of an OPTICRAM can be read and stored directly in the microcomputer memory for processing.The light sensitivity of the camera can be adjusted.It is done by adjusting the time interval between charging up all the cells and reading out the logic levels on the cells.foe example for brighter light a shorter time interval is used.

A Micron Eye camera employing an OPTICRAM has been developed by Micron Technology.It contains a printed circuit board with suitable interfacing circuit board with suitable interfacing circuitry so that it can be interfaced to a microcomputer.With this type of sensors bit pattern of images are stored in the computer memory.

An OPTICRAM camera is relatively inexpensive.It can easily be interfaced to a microcomputer.It has enough resolution to be applied to robots and other similar applications.a

RAM

The read and write memory (R/W memory)of a computer is called RAM.The users can write information into RAM  and read information from it.It is accessible to users.The user enters his program and data into RAM.It possesses random access property.In a random access memory any memory location can be accessed in a random manner without going through any other memory location.The accessed in a random manner without going through any other memory location.The access time is same for each memory location. RAM is a voltatile memory.The information written into it is retained in it as long as the power supply is on.As soon as the power supply goes off (or interrupted)its stored information is lost.The programmer has to reload his program and the data into the RAM when  the power supply is resumed.

RAM is not the correct name of R/W memory because both RAM and ROM possess random access property.But R/W memory has been called RAM since long and in practice it has become an established name.Thus R/W memory is commonly called RAM.

There are two important types of RAMs: static RAM and dynamic RAM. Static RAMs retain stored information only as long as the power supply is on.But a dynamic RAM loses its stored information in a very short time( a few milliseconds) even through the power supply is on.In a dynamic RAM a binary state is stored on the gate to source stray capacitor of a transistor of the MOS memory circuit.The presence of charge on the stray capacitor represents 1,and the absence of charge on the stray capacitor represents 0.The charge on these capacitors leak away as a results of normal leakage in a few milliseconds.Therefore,dynamic RAMs have to be refreshed periodically,generally every 2  milliseconds.The dynamic RAMs are cheaper and have high packing density and moderate speed. They consume less power.They are used where large capacity of memory is needed.Static RAMs are costlier and consume more power.They do not need refreshing circuitry.They have higher speed than dynamic RAMs.Static RAM dynamic RAM are also written as SRAM and DRAM respectively.

READ ONLY MEMORY(ROM)

ROM stands for "Read only memory".It is nonvolatile memory,i.e.the information stored in it is not lost even if the power supply goes off.It is used for permanent storage of information.It also possesses random access property. ROMs are much cheaper compared to RAMs  when produced in larger volumes.The stored information can only be read from ROMs at the time of operation.Information can not be written into a ROM by the users/programmers.In other words ROMs are not accessible to users.The contents of ROMs are decided by the manufacture.From programming mode point of view the ROMs  are placed in broad categories:masked-programmed and user-programmed. ROMs in which contents are written at the time IC manufacture are called mask-programmed ROMs. PROM,EPROM,E^2PROM  or any other kind of PROM are userprogrammable ROMs. If we supply write or say ROMs are are called PROM,EPROM,EEPROM etc.

ROMs store information which is not subject to change.They store fixed programs.In microprocessor-based systems which are used for industrial controls,ROMs store monitor,assembler,debugging package,function tables such as sine,cosine,logrithm,square root,exponential and code conversion tables,etc. 

CD-ROM

It is an optical  ROM.Prerecorded data can be read out.The manufactures writes data on CD-ROMs. The disk is made up of a resin.such as poly carbonate. It is coated with a material which will change when a high intensity laser beam is focused on it.The coating material is highly reflective,usually aluminium.The high intensity laser beam forms a tiny pit along a track to represent 1. For reading the data laser beam of less intensity is employed. A laser systems needs 25mW for writing whereas only 5 mW for reading.In some cases separated laser beams are employed:one for writing and the other for reading.the reflected laser is sensed by photodiode to read data.The intensity of the reflected light of laser changes as it encounter pit. A pit spreads the light so that the photodiode receives little reflected light.But surface without pit reflect sufficient light to the photodiode. Thus the change in reflected light is sensed and converted into electrical signals for data reading purpose.

If the coating of the special material on the optical disk is thin film,a hole is formed when the laser beam falls on it.If the layer is a thick film a pit is formed.In some process of thick film,a bubble is formed instead of a pit.The unaltered areas between the pits are known as lands. 

First of all,a master disk is prepared.By molding a special plastic to the master disk.CD-ROMs are produced on mass scale.The plastic copy of the data is then covered with a clear plastic layer and backed with a reflecting coating. 

DIRECT ACCESS STORAGE DEVICES(DASDs)

The outline secondary storage which is always available to a processor is called direct access storage devices (DASD).The commonly used DASDs are magnetic disks.The optical disks,RAM disks and bubble memory,if incorporated in a system are also DASDs.This term DASD is in the context of permanents type directly accessible long term storage device(i.e.directly accessible secondary storage). As far as the term direct access is connected all semiconductor memories RAMs,ROMs,PROMs are directly accessible and have random access property.Out of these RAMs are for users and they have been categorized as primary memory.In the literature DASDs  are also called ramdom access memory.

MEMORY MANAGEMENT UNIT (MMU)

The function of a memory management unit is to convert logical memory address into actual physical (real) memory address and provide protection.The MMU is a hardware component placed in between the processor and the main memory.some modern CPUs contain on-chip MMU such as 80286,80386,68030 etc. The CPU which does not contain on-chip MMU uses external MMU. The MMU is used in a mutliprogramming or multiuser system.The tasks which are performed by MMU can be performed by the operating system.Then the operating system.Then the operating system will not get sufficient time for program execution and its other tasks. The MMU reduces the burden of the operating system.the memory addresses used in a program are logical addresses.They indicate the logical position of instructions and data in the program. A logical address is the logical position of instructions and data in the program.A logical address is the location of an instruction or data relative to the program.A logical address is the location of an instruction or data relative to the beginning of the program.

when a  program is compiled each logical address is represented by a memory pointer consisting of two components.In a segment oriented system the two components are:segment selector and offset.In a page oriented system the two components are:page address and page offset.In a page oriented system the two components are:page address and page offset.In other words a logical address is represented by a page number and a page offset.