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8. Types of Operating System

1. Interactive operating system

An interactive operating system is one that allows the user to directly interact with the operating system whilst one or more programs are running.

interactive operating system
There will be an user interface in place to allow this to happen. It could be a command line style of interface or it could be a graphical interface.
Most operating systems are of this type

2. Batch operating system

The users of a batch operating system do not interact with the computer directly. Each user prepares his job on an off-line device like punch cards and submits it to the computer operator. To speed up processing, jobs with similar needs are batched together and run as a group. The programmers leave their programs with the operator and the operator then sorts the programs with similar requirements into batches.

The problems with Batch Systems are as follows −

  • Lack of interaction between the user and the job.
  • CPU is often idle, because the speed of the mechanical I/O devices is slower than the CPU.
  • Difficult to provide the desired priority.

3. Single user operating system

Single user operating systems can be split into two types:

  • single user, single application operating systems
  • single user, multi tasking operating systems

Single user, single application

single user single app device

This type of operating system only has to deal with one person at a time, running one user application at a time.

An example of a this kind of operating system would be found on a mobile phone or an iPad. There can only be one user using the device and that person is only using one of its applications at a time.

Single user, multi-tasking

You will find this kind of operating system on a personal computer.

The operating system is designed mainly with a single user in mind, but it can deal with many applications running at the same time. For example, you might be writing an essay, while searching the internet, downloading a video file and also listening to a piece of music.

Example operating systems are

  • Windows (all versions_
  • Linux
  • Mac OS X Leopard.

The difference compared to the Single-Use, Single Application operating system is that it must now handle many different applications all running at the same time.
The memory available is also very different, for example it is quite normal to have Gigabytes of RAM available on a personal computer which is what allows so many applications to run.

4. Multi programming operating system

To overcome the problem of underutilization of CPU and main memory, the multiprogramming was introduced. The multiprogramming is interleaved execution of multiple jobs by the same computer.

In multiprogramming system, when one program is waiting for I/O transfer; there is another program ready to utilize the CPU. So it is possible for several jobs to share the time of the CPU. But it is important to note that multiprogramming is not defined to be the execution of jobs at the same instance of time. Rather it does mean that there are a number of jobs available to the CPU (placed in main memory) and a portion of one is executed then a segment of another and so on. A simple process of multiprogramming is shown in figure

Operation of Multiprogramming System

As shown in fig, at the particular situation, job’ A’ is not utilizing the CPU time because it is busy in I/ 0 operations. Hence the CPU becomes busy to execute the job ‘B’. Another job C is waiting for the CPU for getting its execution time. So in this state the CPU will never be idle and utilizes maximum of its time.

A program in execution is called a “Process”, “Job” or a “Task”. The concurrent execution of programs improves the utilization of system resources and enhances the system throughput as compared to batch and serial processing. In this system, when a process requests some I/O to allocate; meanwhile the CPU time is assigned to another ready process. So, here when a process is switched to an I/O operation, the CPU is not set idle.

Multiprogramming is a common approach to resource management. The essential components of a single-user operating system include a command processor, an input/ output control system, a file system, and a transient area. A multiprogramming operating system builds on this base, subdividing the transient area to hold several independent programs and adding resource management routines to the operating system’s basic functions.


7. Software and its function

1. Software at BIOS level or Firmware and give its examples .

In electronic systems and computing, firmware is a tangible electronic component with embedded software instructions, such as a BIOS. Typically, those software instructions are used to tell an electronic device how to operate. As of 2013, most firmware can be updated. Typical examples of devices containing firmware are embedded systems (such as traffic lights, consumer appliances, and digital watches), computers, computer peripherals, mobile phones, and digital cameras. The firmware contained in these devices provides the control program for the device.

Examples of firmware include:

2. Core of software or Kernel and its examples

I have noticed that term “Core” is mainly used for CPU cores and “Kernel” for OS kernels.

Kernel is the lowest level of the Operating System (Software). Understand that, it is a connecting Bridge between the Software part and Hardware part.

Kernel establishes a connection between the Hardware and Software of your mobile or any device. They cannot connect each other directly. Kernel is just above the hardware. Other software run above it.

A Kernel is the central part of an operating system. It manages the operations of the computer and the hardware, most notably memory and CPU time.

There are five types of kernels:

  • A micro kernel, which only contains basic functionality;
  • A monolithic kernel, which contains many device drivers.
  • Hybrid Kernel
  • Exo Kernel
  • Nano Kernel

A computer user never interacts directly with the kernel. It runs behind the scenes and cannot be seen, except for the text logs that it prints.

3. Operating System Software and its examples

An operating system is a powerful, and usually large, program that controls and manages the hardware and other software on a computer.

Most software applications are designed to work with just one company’s operating system, like just Windows (Microsoft) or just macOS (Apple).

Examples of Operating Systems

Laptops, tablets, and desktop computers all run operating systems that you’ve probably heard of. Some examples include versions of Microsoft Windows (like Windows 10, Windows 8, Windows 7, Windows Vista, and Windows XP), Apple’s macOS (formerly OS X), Chrome OS, BlackBerry Tablet OS, and flavors of the open source operating system Linux.

Screenshot of the Windows 10 desktop

All computers and computer-like devices require operating systems, including your laptop, tablet, desktop, smartphone, smartwatch, and router.

4. Device Driver Software and its axamples

A device driver is a particular form of software application that is designed to enable interaction with hardware devices. Without the required device driver, the corresponding hardware device fails to work.

A device driver usually communicates with the hardware by means of the communications subsystem or computer bus to which the hardware is connected. Device drivers are operating system-specific and hardware-dependent. A device driver acts as a translator between the hardware device and the programs or operating systems that use it.A device driver may also be called a software driver.

SafeBytes Software

5. Utility Software Utility , its fucntion and give examples

This is a program used frequently by the computer to carry out routine jobs Utility software is used to manage computer files, diagnose and repair computer problems and assist in helping the computer to run more efficiently.

Examples :
– Text editors
– Sort utility
– Language translators
– Merge utility
– Loaders:Help in transferring an application from a secondary storage to a primary storage when running the application.
– Copy utility
– Linkers: Linkers enable several programs (modules) to subroutines to be connected when running
– Dump utility
– Diagnostic tools
– Database management system
-Debuggers:Help in tracing and removing errors from a program.

6. Programming Language Software and examples

Programming languages are the instructions that a computer can understand. A computer is basically a collection of circuits that use current as a means to do certain tasks. How could one talk to a computer and tell it what to do? Well, the only language that the computers will understand is the language of electric currents. Thus we need a machine language to communicate with a computer.

Following are some examples of the most common or famous programming languages:

  1. FORTRAN: It stands for Formula Translation. Used for mathematical calculations.
  2. CORAL: It stands for Computer Online Real-time Applications Language.
  3. HTML: It stands for Hyper Text Markup Language.
  4. COBOL: It stands for Common Business Oriented Language.

Other examples include LISP, ALGOL, Pascal, C, C ++, C #, Python, R etc. are all examples of some programming languages.

7. Database Software and its examples

Database software is designed to create databases and to store, manage, change, search, and extract the information contained within them. A comprehensive database software program is sometimes called a database management system.

Mainly, database software exists to protect the information in the database and ensure that it’s both accurate and consistent. Database software functions include:

  • data storage
  • data backup and recovery
  • data presentation and reporting
  • multi-user access control
  • data security management
  • database communication

    What are examples of database software programs?

    Some of the most well-known database software programs include:

    • ADABAS
    • IBM DB2
    • Microsoft Access
    • Microsoft Excel
    • Microsoft SQL Server
    • MySQL
    • Oracle RDBMS
    • Quick Base
    • SAP Sybase ASE
    • Teradata

8. Application Software and its examples

Application software is a type of computer program that performs a specific personal, educational, and business function. Each program is designed to assist the user with a particular process, which may be related to productivity, creativity, and/or communication.

Functions of Application Software

Application software programs are created to facilitate a variety of functions, including but not limited to:

  • managing information
  • manipulating data
  • constructing visuals
  • coordinating resources
  • calculating figures

Examples of Application Software

The most common application software programs are used by millions every day and include:

  • Microsoft suite of products (Office, Excel, Word, PowerPoint, Outlook, etc.)
  • Internet browsers like Firefox, Safari, and Chrome
  • mobile pieces of software such as Pandora (for music appreciation), Skype (for real-time online communication), and Slack (for team collaboration)


6. External storage

1. Floppy Disk

A floppy disk is a magnetic storage medium for computer systems. The floppy disk is composed of a thin, flexible magnetic disk sealed in a square plastic carrier. In order to read and write data from a floppy disk, a computer system must have a floppy disk drive (FDD). A floppy disk is also referred to simply as a floppy. Since the early days of personal computing, floppy disks were widely used to distribute software, transfer files, and create back-up copies of data. When hard drives were still very expensive, floppy disks were also used to store the operating system of a computer.
A number of different types of floppy disks have been developed. The size of the floppy got smaller, and the storage capacity increased. However, in the 1990s, other media, including hard disk drives, ZIP drives, optical drives, and USB flash drives, started to replace floppy disks as the primary storage medium.

Floppy Disks

Types of Floppy Disks

The first floppy disks that came on the market were 8 inches (200 mm) in diameter. The disk was protected by a flexible plastic jacket. An 8-inch disk back in the late 1970s could store about 1 MB of data. This was quickly followed by a smaller version of the same design, the 5.25-inch (133 mm) floppy, which could store about the same amount of information using higher-density media and recording techniques.

In the early 1980s, the 3.5-inch (90 mm) floppy, or micro floppy, came on the market, and this type became the dominant storage medium for personal computers for many years. Each of these floppy disks required a different type of floppy disk drive. These were typically built into the computer case itself.

Floppy disks were quite vulnerable. The disk medium was very sensitive to dust, moisture, and heat. The flexible plastic carrier was also not very sturdy. The hard plastic case of the 3.5-inch floppy presented a substantial improvement in this respect. The most common format of this floppy became the double-sided, high-density 1.44 MB disk drive.

2. Reel Tape

Reel Tape is the oldest form of magnetic tape in the form of audio recording where magnetic recording media is held on a reel ,. This tool has a width of 0.5 inches and reaches 2400 feet in length. usually also has a density or a density level of up to 6250 bits per inch. Each magnetic tape reel has two areas that are not used to record data called a leader.

How it Works Reel Tape : 
The performance of the reel tape is greatly influenced by the width of the track used to record the signal, and the speed of the tape. The wider and faster the better, but of course this uses more recording. Reel tape can hold multiple parallel tracks, so it’s not only stereo recording, but multi-track recording too. This gives the final edit manufacturer greater flexibility, which allows performance to be remixed long after the initial performance is recorded. a tool for recording and reading data on a magnetic tape is a tape drive.

Advantages of Reel Tape
Performance to be recorded without a 30 minute time limit from a black disc.
Performance is recorded so that it can be edited.
The recording can be edited by cutting and pasting the tape.

Lack of Reel Tape
The shape is still complicated.
Must cut and paste the ribbon to edit it.
Using a ribbon that is still very simple and thin

3. Tape cartridge


A tape cartridge is a storage device that contains a spool of magnetic tape used to store different kinds of data, from corporate data to audio and video files. Each cartridge is designed to fit into a compatible audio/video recorder system or computer system. In the context of computing, however, a tape cartridge is the magnetic tape storage cartridge used in tape library units to store digital data on magnetic tape, which is packaged in cassettes and cartridges.Tape cartridges are also known as data cartridges.

A magnetic tape cartridge is an essential component of a robust backup system, which makes use of tape libraries for long-term backup storage. The tape cartridge is the actual piece of hardware that data is saved to; through an autoloader or a robot, the cartridge is inserted into one of many tape drives within a tape library unit for reading and writing.

Because of the nature of the tape cartridge, only sequential writing and reading are possible, so if a specific file needs to be located, the tape drive must read the tape cartridge from the beginning of the spool until it reaches the specific file location. This can take time and is the biggest drawback of a storage system using magnetic tape cartridges. However, tape is cheaper per gigabyte compared to hard drives and solid-state drives, making it ideal for long-term storage archiving.

4. Flash Disk

A storage module made of flash memory chips. Flash disks have no mechanical platters or access arms, but the term “disk” is used because the data are accessed as if they were on a hard drive. The disk storage structure is emulated.
The first flash disks were housed in Type II PC Cards for expanding laptop storage. Subsequently, flash memory disks have arrived in a variety of formats, including entire hard drive replacements (see SSD), memory cards for digital cameras (see flash memory) and modules that fit on a keychain (see USB drive).

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Early Flash Disks
The 40MB and 175MB modules are Type II PC Cards. Not even one gigabyte, their capacity is utterly minuscule by today’s standards. Nevertheless, they provided extra storage for the first laptops. The 15MB module is an earlier CompactFlash camera card.

5. SSD

(Solid State Drive) An SSD is an all-electronic non-volatile storage device that is an alternative to, and is increasingly replacing, hard disks. Employed in myriad products, including mobile devices, iPods, cameras, laptops and desktop computers, SSDs are faster than hard disks because there is zero latency (no read/write head to move). They are also more rugged and reliable and offer greater protection in hostile environments. In addition, SSDs use less power and are not affected by magnets.
In time, there will only be solid state storage, and spinning disk platters will be as obsolete as the punch card (see future memory chips). See disk on module and garbage collection.
Mostly Flash Memory
SSDs are made of flash memory chips 99% of the time. However, for the absolute fastest storage speed obtainable, there are SSDs that use volatile RAM chips backed up by non-volatile storage in case of power failure (see nvSRAMand BBSRAM).
Hybrid Drive (SSD and Disk)
Hybrid drives, such as the Fusion Drive in Macs, combine an SSD with a hard disk (see solid state hybrid drive and Fusion Drive).

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Hard Drive Replacement Kits
This Kingston kit includes everything necessary to replace a desktop computer’s hard drive with an SSD. Laptop kits include an external case for holding the old drive while it is cloned to the SSD.

6. Hard-disk

When you save data or install programs on your computer, the information is typically written to your hard disk. The hard disk is a spindle of magnetic disks, called platters, that record and store information. Because the data is stored magnetically, information recorded to the hard disk remains intact after you turn your computer off. This is an important distinction between the hard disk and RAM, or memory, which is reset when the computer’s power is turned off.

The hard disk is housed inside the hard drive, which reads and writes data to the disk. The hard drive also transmits data back and forth between the CPU and the disk. When you save data on your hard disk, the hard drive has to write thousands, if not millions, of ones and zeros to the hard disk. It is an amazing process to think about, but may also be a good incentive to keep a backup of your data.


(Redundant Array of Independent Disks) A disk or solid state drive (SSD) subsystem that increases performance or provides fault tolerance or both. RAID uses two or more physical drives and a RAID controller, which is plugged into motherboards that do not have RAID circuits. Today, most motherboards have built-in RAID but not necessarily every RAID configuration (see below). In the past, RAID was also accomplished by software only but was much slower. In the late 1980s, the “I” in RAID stood for “inexpensive” but was later changed to “independent.”

In large storage area networks (SANs), floor-standing RAID units are common with terabytes of storage and huge amounts of cache memory. RAID is also used in desktop computers by gamers for speed and by business users for reliability. Following are the various RAID configurations. See NAS and SAN.
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RAID 0 – Striping for Performance (Popular)
Widely used for gaming, striping interleaves data across multiple drives for performance. However, there are no safeguards against failure. See RAID 0.

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RAID 1 – Mirroring for Fault Tolerance (Popular)
Widely used, RAID 1 writes two drives at the same time. It provides the highest reliability but doubles the number of drives needed.
RAID 10 combines RAID 1 mirroring with RAID 0 striping for both safety and performance. See RAID 1 and RAID 10.

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RAID 3 – Speed and Fault Tolerance
Data are striped across three or more drives for performance, and parity is computed for safety. Similar to RAID 3, RAID 4 uses block level striping but is not as popular. See RAID 3 and RAID parity.

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RAID 5 – Speed and Fault Tolerance (Popular)
Data are striped across three or more drives for performance, and parity is computed for safety. RAID 5 is similar to RAID 3, except that the parity is distributed to all drives. RAID 6 offers more reliability than RAID 5 by performing more parity computations. For more details, see RAID 5.

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EMC has been a leader in high-end RAID systems for years with systems storing multiple terabytes of data. (Image courtesy of EMC Corporation.)
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Little RAID
Arco was first to provide RAID 1 on IDE disk drives rather than SCSI. This two-drive unit connected to the motherboard with one cable like a single drive. (Image courtesy of Arco Computer Products, Inc.,


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Early RAID
This RAID prototype was built by University of Berkeley graduate students in 1992. Housing 36 320MB disk drives, total storage was 11GB.


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Super Talent’s USB 3.0 RAID drives provide RAID 0 storage that is faster than an internal hard drive.


5. Internal Memory

1. Register

A register is a temporary storage area built into a CPU. Some registers are used internally and cannot be accessed outside the processor, while others are user-accessible. Most modern CPU architectures include both types of registers.

Internal registers include the instruction register (IR), memory buffer register (MBR), memory data register (MDR), and memory address register (MAR). The instruction register fetches instructions from the program counter (PC) and holds each instruction as it is executed by the processor. The memory registers are used to pass data from memory to the processor. The storage time of internal registers is extremely temporary, as they often hold data for less than a millisecond.

User-accessible registers are larger than internal registers and typically hold data for a longer time. For example, a data register may store individual values referenced being by a currently running program. An address register contains memory addresses, which reference different blocks of memory within the system RAM. Many CPUs now have general purpose registers (GPRs), which may contain both data and memory addresses.

Registers vary in both number and size, depending on the CPU architecture. Some processors have 8 registers while others have 16, 32, or more. For many years, registers were 32-bit, but now many are 64-bit in size. A 64-bit register is necessary for a 64-bit processor, since it enables the CPU to access 64-bit memory addresses. A 64-bit register can also store 64-bit instructions, which cannot be loaded into a 32-bit register. Therefore, most programs written for 32-bit processors can run on 64-bit computers, while 64-bit programs are not backwards compatible with 32-bit machines.

2. Cache

Cache is generally divided into several types, such as L1 cache, L2 cache and L3 cache. Cache built into the CPU itself is referred to as Level 1 (L1) cache. Cache is in a separate chip next to the CPU is called Level 2 (L2) cache. Some CPUs have both, L1 and L2 cache built-in and assign a separate chip as cache Level 3 (L3) cache. Cache built in CPU faster than separate cache. However, a separate cache is still about twice as fast from Random Access Memory (RAM). Cache is more expensive than RAM, but the motherboard with built-in cache very well in order to maximize system performance. 

 Types Of Internal Memory
Advantage of Cache:
Cache serves as a temporary storage for data or instructions needed by the processor. In addition, the cache function to speed up data access on the computer because the cache stores data / information has been accessed by a buffer, to ease the work processor.
Another benefit of cache memory is that the CPU does not have to use the bus system motherboard for data transfer. Each time the data must pass through the system bus, the data transfer rate slow the ability motherboard. CPU can process data much faster by avoiding obstacles created by the system bus..

3. ROM

Sometimes can be erased for reprogramming, but might have odd requirements such as UV light or erasure only at the block level
Sometimes require special device to program, i.e., processor can only read, not write.

  • Data are written into a ROM when it is manufactured.
  • ROM is mask programmed by the manufacturer in the factory with the contents ordered by the customers.
  • The contents are fixed by metal masks used during chip fabrication.
  • Once programmed, the contents cannot be erased.
  • Even a single bit wrongly programmed the ROM chip is useless

 Types Of Internal Memory

  • Used to store control programs such as micro program.
  • Character generation, code conversion
  • Permanent storage – nonvolatile
  • Microprogramming
  • Library subroutines
  • Systems programs (BIOS)
  • Function tables
  • Embedded system code

Types of ROM

  • PROM (Programmable Read Only Memory)
  • EPROM (Erasable Programmable Read Only Memory )
  • EEPROM (Electrically Erasable Programable Read Only Memory)

If the content is determined by the vendor ROM, PROM sold empty and can then be filled with a program by the user. Having completed the program, fill PROM cannot be removed.

PROM (Programmable Read Only Memory)
  • PROM is a field programmable device.
  • The customer buy a blank PROM and store desired data using PROM programmer(burner).
  • Programmability achieved by inserting a fuse at point P.
  • Before programmed, the memory contains all 0s
  • The user can insert 1 by burning out the fuse in the particular cell using high current pulse.
  • The PROM chip can be programmed only once and its contents cannot be erased.
  • PROM are flexible, faster and less expensive because they can be programmed directly by the user.
EPROM (Erasable Programmable Read Only Memory )
  • A rewritable chip that holds its contents without power. Previous data can be erased and new data can be inserted
  • EPROM chips are written on an external programming device before being placed on the circuit board. Capable of retaining stored information for a long time.
  • Eraser contd., requires breakup the charges trapped in the transistors of memory cell.[this is done by break the chip to ultraviolet light].
  • This reason EPROM packaged with transparent window.
  • Disadvantages: Entire EPROM is erased as a whole and selective erasing is not possible.
  • Should be removed from the chip for reprogramming.
  • Unlike the PROM, EPROM contents can be deleted after being programmed. Elimination is done by using ultraviolet light.
EEPROM (Electrically Erasable Programable Read Only Memory)
EEPROM can store data permanently, but its contents can still be erased electrically through the program. One type EEPROM is Flash Memory. Flash Memory commonly used in digital cameras, video game consoles, and the BIOS chip.
  • It can be both programmed and erased electrically ( flashed back to Zero).
  • They do not need to removed when the chip content erasure.
  • Also, erase selected content in the chip.
  • Erasing and programming dynamically without removing the EEPROM from the circuit.


  • Different voltages are required for erasing, reading and writing the data.

4. RAM

Random access memory, or RAM, is memory storage on a computer that holds data while the computer is running so that it can be accessed quickly by the processor. RAM holds the operating system, application programs and data that is currently being used.

RAM data is much faster to read than data stored on the hard disk. RAM is stored in microchips and contains much less data than the hard disk. RAM can never run out of memory, but the processor must overwrite old data if the RAM is filled, which results in slower computer function. Any file stored in RAM can be accessed directly if the user knows the row and column where the data is stored.

  • Random access memory is used to store temporary but necessary information on a computer for quick access by open programs or applications.
  • RAM, is a volatile yet fast type of memory used in computers. RAM is more expensive to incorporate.
  • RAM allows reading and writing (electrically) of data at the byte level
  • RAM is the Volatile memory.

Types of RAM

  • Static RAM
  • Dynamic RAM
Static RAM stores a bit of information in a flip-flop. Static RAM is usually used for applications that do not require large capacity RAM memory.Static(RAM) is a memory technology based on flip-flops. SRAM has an access time of 2 – 10 nanoseconds. All of main memory can be viewed as fabricated from SRAM, although such a memory would be unrealistically expensive.
Dynamic RAM data store one bit of information as a payload. Dynamic RAM using a substrate capacitance gate MOS transistors as memory cells shut. To keep dynamic RAM stored data remains intact, the data should be refreshed again by reading and re-write the data into memory. Dynamic RAM is used for applications that require large RAM capacity, for example in a personal computer (PC)
  • EDO (Extended Data-output) and SD (Synchronous Dynamic Random Access Memory) are type of Dynamic RAM.
  • Dynamic RAM (DRAM) is a memory technology based on capacitors
  • Dynamic RAM is cheaper than static RAM and can be packed more densely on a computer chip
  • DRAM has an access time in the order of 60 – 100 nanoseconds, slower than SRAM.

 Types Of Internal Memory

5. SWAP memory

A swap file (or swap space or, in Windows NT, a pagefile) is a space on a hard disk used as the virtual memory extension of a computer’s real memory (RAM). Having a swap file allows your computer’s operating system to pretend that you have more RAM than you actually do. The least recently used files in RAM can be “swapped out” to your hard disk until they are needed later so that new files can be “swapped in” to RAM. In larger operating systems (such as IBM’s OS/390), the units that are moved are called pages and the swapping is called paging.

In general, Windows and UNIX-based operating systems provide a default swap file of a certain size that the user or a system administrator can usually change.

6. Virtual memory

The virtual memory functions enable a process to manipulate or determine the status of pages in its virtual address space. They can perform the following operations:

  • Reserve a range of a process’s virtual address space. Reserving address space does not allocate any physical storage, but it prevents other allocation operations from using the specified range. It does not affect the virtual address spaces of other processes. Reserving pages prevents needless consumption of physical storage, while enabling a process to reserve a range of its address space into which a dynamic data structure can grow. The process can allocate physical storage for this space, as needed.
  • Commit a range of reserved pages in a process’s virtual address space so that physical storage (either in RAM or on disk) is accessible only to the allocating process.
  • Specify read/write, read-only, or no access for a range of committed pages. This differs from the standard allocation functions that always allocate pages with read/write access.
  • Free a range of reserved pages, making the range of virtual addresses available for subsequent allocation operations by the calling process.
  • Decommit a range of committed pages, releasing their physical storage and making it available for subsequent allocation by any process.
  • Lock one or more pages of committed memory into physical memory (RAM) so that the system cannot swap the pages out to the paging file.
  • Obtain information about a range of pages in the virtual address space of the calling process or a specified process.
  • Change the access protection for a specified range of committed pages in the virtual address space of the calling process or a specified process.


The functions of computer

a. Computer as data processing :

Data processing is the conversion of data into usable and desired form. This conversion or “processing” is carried out using a predefined sequence of operations either manually or automatically. Most of the data processing is done by using computers and thus done automatically. The output or “processed” data can be obtained in different forms like image, graph, table, vector file, audio, charts or any other desired format depending on the software or method of data processing used. When done itself it is referred to as automatic data processing.

Data Processing - Understanding Data

Fundamentals of data processing & how data is processed

Data processing is undertaken by any activity which requires a collection of data. This data collected needs to be stored, sorted, processed,analyzed and presented , This complete process can be divided into 6 simple primary stages which are:

  1. Data collection
  2. Storage of data
  3. Sorting of data
  4. Processing of data
  5. Data analysis
  6. Data presentation and conclusions

    Methods of data processing

    1. Manual data processing: In this method data is processed manually without the use of a machine, tool or electronic device.  Data is processed manually, and all the calculations and logical operations are performed manually on the data.
    2. Mechanical data processing – Data processing is done by use of a mechanical device or very simple electronic devices like calculator and typewriters. When the need for processing is simple, this method can be adopted.
    3. Electronic data processing – This is the modern technique to process data. Electronic data processing is the fastest and best available method with the highest reliability and accuracy. The technology used is latest as this method used computers and employed in most of the agencies. The use of software forms the part of this type of data processing. The data is processed through a computer; Data and set of instructions are given to the computer as input, and the computer automatically processes the data according to the given set of instructions. The computer is also known as electronic data processing machine.Sorting & Filtering of data

      Types of Data processing on the basis of process/steps performed

      1. Batch Processing
      2. Real-time processing
      3. Online Processing
      4. Multiprocessing
      5. Time-sharing

b. Computer as data storage :

Computers use a variety of data storage devices that are classified in two ways: one is whether they retain the data if there is no electricity and the other is how close they are to the processor (CPU). Both types of storage are needed in all computers. In a personal computer, memory does not retain data when the electricity is off, but while it is on, it enables quick access to open files. A storage drive, however, allows you to permanently store data, so it’s available each time you turn on the computer.

Volatile and non-volatile storage

The first classification of computer data storage is between volatile and non-volatile storage. An example of volatile storage is memory (RAM) that stores data only until there is no electricity powering the device. RAM allows your computer to have multiple files open and access any of them instantly. Some other examples of volatile storage devices are calculators.

A Crucial DDR4 UDIMM RAM memory module
Non-volatile storage is storage that maintains the data even when there is no electricity powering the device. An example is a hard disk drive (HDD) or solid state drive (SSD) that holds all of the data saved to your computer. There is other non-volatile storage, such as DVDs or flash drives.
Two examples of non-volatile storage including a USB flash drive and a Crucial SSD

Storage hierarchy

Computer data storage devices are also classified by their distance from the processor, or CPU. The closest storage is memory, or RAM. This is the only kind of data storage that directly accesses the CPU. Memory includes processor registers and the processor cache, but these are included on the memory module.

Memory is volatile storage, so any information that goes into memory needs to be written to the main storage device to be retained permanently. Because data flows from memory to a storage device, it’s considered secondary storage.

For most personal computers, secondary storage is the main data storage device. A hard disk drive or solid state drive holds all of the data; files, photos, programs, music, and movies, that the user wants to keep. Removable, external media storage devices such as flash drives and read/writeable CDs and DVDs are also secondary storage. A computer can’t function without a storage drive, however. The storage drive also holds all the information the computer needs to run.

Tertiary storage is computer data storage that uses removable media, such as a tape drive, and it uses a robot to retrieve the data. This is rarely used in personal applications.

c. Computer as data movement :

Data movement instructions move data from one place, called the source operand, to another place, called the destination operand. Data movement instructions can be grouped into loads, stores, moves, and immediate loads.

Load instructions move data from memory to registers.
Store instructions move data from registers to memory.
Move instructions move data from one register to another.
Immediate load instructions move constants, including addresses, to registers.

d. Computer as controlling system

A control system is a set of devices that work together to regulate an environment or achieve some set objectives.  This is achieved through a control loop.

Examples of control systems:

  • Maintaining healthy conditions in a fish tank
  • Automatic shop doors
  • Automatic street or security lighting
  • Burglar alarms
  • Automated greenhouses
  • Heating and cooling systems

How does a control system work?

To understand how a control system works, it helps to remember how a computer system is structured (see diagram below).

Computer System Diagram

  1. Input devices, usually sensors, send data readings to the microprocessor (computer) at set intervals
  2. To be understood, this data may have to be converted using an ADC (analogue to digital converter)
  3. The microprocessor compares the data readings against pre-set values that it has stored (using a control program)
  4. The microprocessor then makes a decision as to whether any action is needed (e.g. is more heat needed to maintain the pre-set value?)
  5. If needed, the microprocessor will send a signal to instruct an output device to do something (e.g. turn on heater, turn off oxygen pump etc)
  6. This may involve an actuator (e.g. a motor to open the gates or shop doors)
  7. This process repeats in a continuous loop


At no point does an input device directly communicate with an output device, or make any judgement calls.  Because of this, a statement such as the following is completely wrong:

“When it gets dark, the light sensor turns on the light bulb”

The computer system diagram above confirms this cannot happen.

Benefits of control systems

  • Computers are quick to respond to change and can process data very quickly
  • Can run all day every day, without wages or needing a break
  • Can operate in places dangerous to humans
  • Consistent and error free