computer introduction

                                     computer  introduction

what is computer? Explain characteristics of computer and draw block diagram of computer?

The term computer comes from Greek word “Compute” means calculate. A computer is a programmable device made to collect input, carry out logical and mathematical operations automatically and sequentially, and produce the intended output, or information, after processing.

Hardware and software make up the two main categories of computer parts. Hardware includes the machine itself as well as any attached components, such as a monitor, keyboard, or mouse. Software is a collection of programmes that employ hardware to carry out specific tasks.

                                    Block diagram of computer 

      block diagram of a computer   gives you the pictorial representation of a computer

that how it word inside

In the above diagram, both control (control unit or CU) and arithmetic & logic unit (ALU) combine called as Central Processing Unit (CPU).

 The processor Unit(CPU)

All important calculation and comparisons are made inside the CPU and it is also responsible for activation and directing the operation of other unit.

This unit consists of two major components, that are arithmetic logic unit (ALU) and control unit (CU) (CU).

Arithmetic Logic unit(ALU)

All arithmetic operations, including addition, subtraction, multiplication, and division, are carried out here by the arithmetic logic unit. Additionally, it compares using logic operations.

Control unit(CU)

Additionally, a CPU's control unit manages all aspects of computer operation. Additionally, it manages all hardware connected to the CPU, including memory and input/output devices.

Input/output unit

The data entered through the input unit is placed in the computer's memory for processing, and the finished product can be recorded or displayed on the output medium once it has been saved in memory.

Memory unit

A digital computer's memory unit is a crucial part. It is the location where all data is kept, both final and interim.

The information is transported to the computer's memory, where it can be processed after being read from the main storage or an input device.

 Characteristics of computer

Speed:- In general, no human being can match a computer's speed at solving a difficult computation.

Accuracy:- Since a computer is programmed, any input we provide will produce an accurate result.

Storage:- A computer is capable of bulk data storage in the right format.

Diligence:- A computer can work nonstop for hours without stopping or making mistakes.

Versatility:- We can use computers to execute a variety of tasks simultaneously.

Power of remembering :- It can save information for us.

No IQ:- Without instructions, a computer cannot function.

No feeling:- Computers lack feelings, knowledge, experience, and emotions. 

 Functional Unit

A. Input Unit:- 

This unit is used for entering data and programmes into the computer system by the user for processing

B. Storage Unit:-

The storage unit is used for storing data and instructions before and after processing.

C. Output unit:-The result that the computer produces as output after processing is stored in the output unit.

D. processing:-

Processing is the process of carrying out operations such as arithmetic and logical processes. Based on the instructions given and the kind of data provided, the Central Processor Unit (CPU) uses the data and instructions from the storage unit to perform a variety of calculations. Afterwards it is returned to the storage space. Arithmetic logic unit (ALU) and control unit are components of the CPU (CU).

 

Memory

What is memory?

The term "memory" refers to the space where programme instructions and data are stored for processing. Like the human brain, computers also need a place to store data and instructions for processing, hence this space is referred to as memory.

The CPU lacks the capability to permanently store vast amounts of data or applications. It only includes the bare minimum of computer operation instructions. Memory is therefore needed.

   Types of Computer Memory

Memories primarily is of two types as given here:

•      Internal Memory

        •       Random Access Memory (RAM)

                    •       Static RAM (SRAM)

                    •       Dynamic RAM (DRAM)

          •       Read Only Memory (ROM)

                    •       Programmable Read Only Memory (PROM)

                    •       Erasable and Programmable Read Only Memory (EPROM)

                    •       Electrically Erasable and Programmable Read Only Memory (EEPROM)

             •       Cache Memory

•       External Memory

•       External Hard Drives

•       USB Flash Drive

  Random Access Memory (REM):-

                                                       The internal memory of the CPU is made up of a RAM, which is used to store data, programmes, and programme results. The memory is read-write. The term "it" is "Random Access Memory" (RAM).

Data saved in RAM is volatile, meaning information is lost when we turn off the computer, switch it off, or if there is a power outage.

Types of REM

REM is of two types:

. Static  REM (SREM) 

. Dynamic Ram (DRAM)

As long as power is applied, the memory will continue to hold its contents, as indicated by the phrase "static." Unfortunately, because to its volatile nature, data is lost when the power goes off. Static RAM chips have no capacitors and a grid of six transistors. Since transistors don't need power to stop leakage, static RAM doesn't need to be refreshed frequently.

In contrast to static RAM, dynamic RAM requires regular replacement in order to keep the data. By mounting the memory on a refresh circuit, which rewrites the data many hundred times per second, this is accomplished. The majority of system memory is stored in dynamic RAM due to its low cost and small size. Memory cells make up all dynamic rams. In these cells

Read Only Memory(REM):-

Read-only memory is referred to as ROM. The memory that we are only able to read from and not write to. It is non-volatile memory of this kind. During manufacturing, the data is permanently stored in such memories. When electricity is first turned on, a ROM stores the instructions needed to start a computer. This process is known as bootstrapping.

Type of  ROM

       •       Programmable Read Only Memory (PROM)

       •       Erasable and Programmable Read Only Memory (EPROM)

       •       Electrically Erasable and Programmable Read Only Memory (EEPROM)

PROM :-

                 PROM is read-only memory that a user can change only once. A blank PROM is purchased, then using a PROM programmer, the user enters the desired information. Little fuses located inside the PROM are burned open during programming. It cannot be erased and can only be programmed once.

EPROM:-

                By subjecting the EPROM to ultra-violet light for up to 40 minutes, the EPROM can be wiped. An electrical charge is held in an insulated Gate region during programming.

EEPROM:-

                  Electrical currents are used to programme and erase the EEPROM. It has a ten thousand or more reprogramming and wipe cycles. Erasing and programming both take between four and ten milliseconds. Any location in an EEPROM can be programmed or selectively erased.

Cache Memory:-

                        Cache memory is a semiconductor memory with a very fast speed that can accelerate the CPU. Between the CPU and the main memory, it serves as a buffer. It is used to store the data and programmes that the CPU uses the most frequently. Operating systems move data and programme components from disc to cache memory so that CPUs can access them.

Cache memory, often known as CPU memory, is located between the CPU and the main memory.

Advantages of cache Memory

        •       Cache memory is faster than main memory.

•       It consumes less access time as compared to main memory.

•       It is stores the program that can be executed within a short period of time.

•       It stores data for temporary use.

External Memory (Secondary memory /auxiliary memory)

Although secondary memory is slower than main memory, it is significantly greater in size. It often keeps data files, instructions, and system applications. Auxiliary memory is another name for it. It can also be used as a virtual memory or overflow in the event that the main memory's capacity has been reached.

A processor cannot directly access secondary memory. The CPU can access the data/information from the auxiliary memory once it has been transferred to the main memory.

Characteristics of Auxiliary Memory

Here are the characteristics of auxiliary:

        . Non volatile memory -Data is not lost when power is cut off

        . Reusable-The data stage is stored permanently in secondary storage as long as it is not overwritten or removed by the user.

        . Reliable-- The great physical stability of secondary storage devices ensures the security of the data stored there.

        . Convenience-- A computer programme makes it easy for authorised users to find and access the data.

         .Capacity-Large data volumes can be stored in sets of many discs in secondary storage.

          .Cost-Data storage on a disc or sellotape is significantly less expensive than in primary memory.

Types of Secondary Storage Device

    To store data for later use, a variety of secondary storage devices are available. These devices enable reading and writing to any location in memory.

Commonly used secondary storage devices are:

•       magnetic tape

•       magnetic disk

•       optical disk 

Magnetic Tape:-

 It resembles audio tape in that a plastic strip covered in magnetic material is present. Binary data storage is the name of the type of data encoding. Magnetic tape can store data in sizes ranging from 60 MB to 24 GB and has a vast storage capacity.

Magnetic Disk 

These are Direct Access storage media, which allows for substantially faster data access since no preceding data must be called in order to access a particular data.

A round diskette (round disc) made of plastic that has been coated in magnetic ink and used as a data storage medium is present in these devices.

The magnetic disk commonly of two types, that are:

•       floppy disk

•       hard disk

Optic Disk

A laser beam may read data from and write data to an optical disc. Large amounts of data can be stored on these discs in GB. They are offered as CD-ROM, erasable optical discs that support WORM (write once, read only). Data can be stored on a CD-ROM once and be read-only. These are referred to as read-only compact discs. They can hold up to 1GB of data. The data from CD-ROM is read using a specialised equipment called a CD-ROM player.

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