NoobToProLearner

CLASSIFICATION OF COMPUTER SOFTWARE Computer software is written by programmers using a programming language. The programmer writes a set of instructions (program) using a specific programming language. Such programs are known as the source code. Another computer program called a compiler is then used on the source code, to transform the instructions into a language that the computer can understand. The result is an executable computer program, which is another name for software. Examples of computer software include the following: Driver software, which allows a computer to interact with hardware devices such as printers, scanners, and video cards. Educational software, which includes programs and games that help in teaching and providing drills to help memorize facts. Educational software can be used in diverse areas, from teaching computer-related activities like typing to subjects like chemistry. Media players and media development software, which are specifically designed to play ...

Secondary Storage Devices Secondary storage (also known as external memory or auxiliary storage) differs from main memory in that it is not directly accessible by the CPU. The secondary storage devices hold data even when the computer is switched off. An example of such a device is the hard disk. The computer usually uses its input/output channels to access data from the secondary storage devices to transfer the data to an intermediate area in the main memory. Secondary storage devices are non-volatile in nature, cheaper than the primary memory, and thus can be used to store huge amounts of data. While the CPU can read the data stored in the main memory in nanoseconds, the data from the secondary storage devices can be accessed in milliseconds. The secondary storage devices are basically formatted according to a file system that organizes the data into files and directories. The file system also provides additional information to describe the owner of a certain file, the access time, t...

Electrically erasable programmable read-only memory (EEPROM )  Electrically erasable programmable read-only memory (EEPROM) allows its entire or selected contents to be electrically erased, then rewritten electrically. The process of writing an EEPROM is also known as flashing.

Erasable programmable read-only memory (EPROM)  Erasable programmable read-only memory (EPROM) is a type of ROM that can be erased and re-programmed. The EPROM can be erased by exposing the chip to strong ultraviolet light typically for 10 minutes or longer and then rewritten with a process that again needs higher than usual voltage applied.

Programmable read-only memory (PROM) Programmable read-only memory (PROM) also called one-time programmable ROM can be written to or programmed using a special device called a PROM programmer. The working of a PROM is similar to that of a CD-ROM recorder which enables the users to write programs just once but the recorded data can be read multiple times. Programming a PROM is also called burning.

Read Only Memory (ROM) ROM refers to computer memory chips containing permanent data. Unlike RAM, ROM is non-volatile, that is, the data is retained in it even when the computer is turned Off. Refer Table 1.2 to understand the key differences between RAM and ROM. Differences between RAM and ROM RAM Data can be read as well as written. Data is stored temporarily. Data is stored while the computer is being used by users to hold their data. It is required while the computer is being used by users to run their applications. ROM Data can only be read. Data is stored permanently. Data is stored during the time of fabrication. It is required for starting the computer, and storing Most computers contain a small amount of ROM that stores critical programs which are used to start the computer when it is turned On. Originally, ROM was actually read only. So, in order to update the programs stored in ROM, the ROM chip had to be removed and physically replaced by the ROM chip that has a new version...

Differences between RAM and ROM RAM Data can be read as well as written. Data is stored temporarily. Data is stored while the computer is being used by users to hold their data. It is required while the computer is being used by users to run their applications. ROM Data can only be read. Data is stored permanently. Data is stored during the time of fabrication. It is required for starting the computer, and storing

Dynamic RAM  Dynamic RAM This is the most common type of memory used in personal computers, workstations, and servers today. A DRAM chip contains millions of tiny memory cells. Each cell is made up of a transistor and a capacitor, and can contain 1 bit of information-0 or 1. To store a bit of information in a DRAM chip, a tiny amount of power is put into the cell to charge the capacitor. Hence, while reading a bit, the transistor checks for a charge in the capacitor. If a charge is present, then the reading is 1; if not, the reading is 0. However, the problem with DRAM is that the capacitor leaks energy very quickly and can hold the charge for only a fraction of a second. Therefore, a refresh process is required to maintain the charge in the capacitor so that it can retain the information. This refreshing process is carried out multiple times in a second and requires that all cells be accessed, even if the information is not needed. However, the advantage of DRAM over SRAM is that ...

Static RAM Static RAM This is a type of RAM that holds data without an external refresh as long as it is powered. This is in striking contrast with the DRAM which must be refreshed multiple times in a second to hold its data contents. SRAM is made of D flip-flops in which the memory cells flip-flop between 0 and 1 without the use of capacitors. Therefore, there is no need for an external refresh process to be carried out. The limitation of SRAM is that it occupies more space and is more expensive than DRAM. While each transistor on a DRAM chip can store one bit of information, the SRAM chip, on the other hand, requires four to six transistors to store a bit. This means that a DRAM chip can hold at least four times as much data as an SRAM chip of the same size, thereby making SRAM much more expensive. However, SRAM is faster, more reliable than DRAM, and is often used as cache memory. SRAM chips are also used in cars, household appliances, and handheld electronic devices.

Random Access Memory (RAM) RAM is a volatile (stores data only when the power is On) storage area within the computer typically used to store data temporarily so that it can be accessed by the CPU. The information stored in RAM is loaded from the computer's hard disk, and includes data related to the operating system and applications that are currently being executed by the processor. RAM is considered as random access because any memory cell can be directly accessed if its address is known. When the RAM gets full, the computer system operates at a slow speed. When multiple applications are being executed simultaneously and the RAM gets fully occupied by the application's data, it is searched to identify memory portions that have not been utilized. The contents of those locations are then copied onto the hard drive. This action frees up RAM space and enables the system to load other pieces of required data. These days, the applications' and operating system's demand for...

Primary memory Primary memory (or main memory or internal memory) can be directly accessed by the CPU. The CPU continuously reads instructions stored in the primary memory and executes them. Any data that has to be operated by the CPU is also stored there. There are two types of primary memory: RAM and ROM, which are discussed as follows.

Cache Memory Cache memory is an intermediate form of storage between registers and the primary memory. It is used to store instructions and data that are repeatedly required to execute programs thereby improving the overall system speed and increase the performance of the computer. Keeping frequently accessed data and instructions in the cache avoids accessing the slower primary memory. Working of the Cache Memory When a program is being executed and the CPU wants to read data or instructions, then the following steps will be performed: CPU first checks whether the data or instruction is available in cache memory. If it is not present, the CPU reads the data or instructions from the main memory into the processor registers. The CPU also copies it into the cache memory. When the same piece of data/instruction is needed, the CPU reads it from the cache memory instead of the main memory

CPU Registers CPU registers are located inside the processor and are therefore directly accessed by the CPU. Registers are the fastest of all forms of computer data storage.

Memory Hierarchy In contemporary usage, memory usually refers to random access memory, typically DRAM (Dynamic RAM) but memory can also refer to other forms of data storage. In computer terminology, the term storage refers to storage devices that are not directly accessible by the CPU (secondary or tertiary storage). Examples of secondary storage include hard disk drives, optical disc drives, and other devices that are slower than RAM but are used to store data permanently. These days, computers use different types of memory which can be organized in a hierarchy around the CPU, as a trade-off between performance and cost. The memory at a higher level in the storage hierarchy has less capacity to store data, is more expensive, and is fastest to access .

  Computer Memory And There Difference. Computer memory is an internal storage area in the computer used to store data and programs eithers temporarily or permanently. A computer memory can be divided into two groups: primary memory, secondary memory. Primary Memory It is more expensive. It is faster and more efficient than secondary memory. Directly accessed by the CPU. It is volatile in nature. Storage capacity is limited. It has no moving parts. The memory is power dependent. The memory is integrated circuit based. It consumes less power. It stores data temporarily. Secondary Memory It is cheaper. It is slower and less efficient than secondary memory. Cannot be accessed directly by the CPU. It is non-volatile in nature. It has large storage capacity. It has moving parts. The memory is power independent. The memory is magnetic or optical based. It consumes more power. It stores data permanently.

Input and Output Devices An input device is used to feed data and instructions into the computer. In the absence of an input device, a computer would have only been a display device. Correspondingly, any device that outputs/gives information from a computer is called an output device. Refer to Figure 1.19 which shows some basic I/O devices that are generally connected with our computer system. Input device Some of the input devices that are widely used by computer users to feed data or instruction to the computer are keyboard, mouse, trackball, joystick, stylus, touch screen, barcode reader, optical character recognition (OCR) device, optical mark recognition (OMR), MICR, web and digital cameras, etc. Output device We can classify the output devices in two categories. S oft copy output devices are those output devices which produce an electronic version of an output. For example, a file which is stored on hard disk, CD, pen drive, etc. and is displayed on the computer screen (monitor)....

What is CPU (Central Processing Unit) Architecture CPU or Central Processing unit can be called the brain of the computer system because the entire processing of data is done here. It is made up of more than one microprocessors which consist of two main parts - Arithmetic and Logical Unit (ALU) and Control Unit(CU) . Arithmetic and Logical Unit The ALU performs all kinds of calculations, such as arithmetic fadd, subtract, multiply, divide, etc.), comparison (less than, greater than, or equal to), and other operations. The intermediate results of processing may be stored in the main memory, as they might be required again. When the processing completes, the final result is then transferred to the main memory. Hence, the data may move from main memory to the ALU multiple times before the processing is over. Control Unit The main function of the CU is to direct and coordinate the computer operations. It interprets the instructions (program) and initiates action to execute them. The CU...

Concept Hardware and Software The concept of hardware and software is very simple in the computer. A computer system is made of two parts- Hardware and Software. Hardware All physical parts of the computer can be said as hardware of the computer. For example, all the input and output devices from the parts of the computer. If we think of computer as a living being, then the hardware would be the body. Since the computer hardware is a part of a machine, it can only understand two basic concepts: 'ON' and 'OFF'. The 'ON' and 'OFF' concepts is called binary. Computer software was developed to tell the computer hardware what to do. Software The computer hardware cannot think and make decision on its own. The hardware needs a software to instruct what to be done. A program is a set of instruction that is arranged in a sequence to guide a computer to find a solution for the given problem. The process of writing a program is called programming .

Components And Function of a Computer  A computer is as electronic device basically perform five major operation, and there components and function of computer are as follow Accepting data or instruction. Storing data Processing data. Displaying results. Controlling and coordinating all operation inside a computer. In this section we will discus all these function and see how one components of computer interacts with another unit to perform these operations using the block diagram in the above. Input - The data and instructions can be entered into the computer system by using different input devices such as keyboard,mouse,scanner,etc. Storage Storage is the process of saving data and instructions permanently in the computer so that it can be used for processing. The computer storage space stores not only the data and programs but also the intermediate results and the final results of processing. A computer has two types of storage areas: Primary Storage Primary storage also kno...

Types of Stored Program Computers A computer with a Von Neumann architecture stores data and instructions in the sa me memory (refer Figure 1.12(a)). There is a serial machine in which data and instructions are selected one at a time. Data and instructions are transferred to and from memory through a shared data bus. Since there is a single bus to carry data and instructions, process execution becomes slower. Later Harvard University proposed a stored program concept in which there was a separate memory to store data and instructions (refer Figure 1.12(b)). Instructions are selected serially from the instruction memory and executed in the processor. When an instruction needs data, it is selected from the data memory. Since there are separate memories, execution becomes faster.