Parts of a Computer

All general-purpose computers has the following main hardware components.

• Memory: Memory enables the computers to store, at least temporarily, data and programs.
• Mass storage device: Allows a computer to permanently retain large amounts of data. Common classic mass storage devices include disk drives and tape drives. The latest being the Hard Disks and USB mass storage devices.
• Input device: The most usual input devices are a keyboard and mouse. They are used to put in data and instructions to computer.
• Output device: The most usual output devices are display screens such as Monitor which are of several types now a days and a printer, or other device that lets us see what the computer has accomplished.
• Central processing unit (CPU): This can be called brain of the computer which actually executes the instructions.

Central Processing Unit

A general purpose computer has four main sections: the arithmetic and logic unit (ALU), the control unit, the memory, and the input and output devices (collectively termed I/O). These parts are interconnected by busses, often made of groups of wires. The control unit, ALU, registers, and basic I/O (and often other hardware closely linked with these) is collectively known as a Central Processing Unit (CPU).

Primitive CPUs were comprised of many separate components but since the mid-1970s CPUs have typically been constructed on a single integrated circuit called a microprocessor. CPU plays a role analogous to the brain in the computer.

The CPU can be a single chip or a series of chips that perform arithmetic and logical calculations and that time and control the operations of the other elements of the system. It was the contribution of the miniaturization and integration techniques that made possible the development of the microprocessor. A Microprocessor is a CPU chip that incorporates additional circuitry and memory. Typical CPU chips and microprocessors are composed of four functional sections:

• Arithmetic/logic unit (ALU): gives the chip its calculating ability and permits arithmetical and logical operations
• Registers: The registers are temporary storage areas that hold data, keep track of instructions and hold the location and results of these operations.
• Control section: The control section times and regulates the operations of the entire computer system; its instruction decoder reads the patterns of data in a designated register and translates the pattern into an activity, such as adding or comparing; and its interrupt unit indicates the order in which individual operations use the CPU and regulates the amount of CPU time that each operation may consume.
• An internal bus: It’s a network of communication lines that connect the internal elements of the processor and also leads to external connectors that link the processor to the other elements of the computer system.

CPU Cache

A CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access memory. The cache is a smaller, faster memory which stores copies of the data from the most frequently used main memory locations.

Motherboard

The motherboard is the main circuit board of the computer and as such acts as the “circulation system” of the computer. All signals used by the computer are processed by the motherboard. Memory chips, the central processor, expansion boards and cables to disk drives all attach to the motherboard. Thus, a motherboard is the data and power infrastructure for the entire computer.

Port

A hardware computer port is a physical interface between a computer and other computers or devices. A software computer port is a virtual data connection between computer programs possibly through a computer network.

USB

USB stands for universal serial Bus and is a common component on new computers. The port looks like a flat slot and there are usually two of them together. These are also called Plug-and-play ports. They are such that once they are in used; the connected devices start handshaking automatically.

BIOS

BIO refers to basic input/output system (BIOS). BIOS software is built into the PC, and is the first code run by a PC when powered on, and that is why it is called boot firmware.  In computing, firmware is software that is embedded in a hardware device. Thus, primary function of the BIOS is to set up the hardware and load and start an operating system.

A computer or laptop keeps track of time even when it is switched off. Why?

A desktop PC has a lithium cell or battery (the same is used in digital diaries) called a BIOS cell inside the CPU, and attached to the motherboard, which keeps track of time even after the computer is powered down, whereas in laptops, the battery of the laptop itself is used to keep track of time. This battery also saves the settings required during a boot operation.

What is difference between Cold Boot and Warm Boot? 

We actually perform a Cold Boot every time we turn on the power switch of our computer. To “boot’’ the computer means to start it up and reset the memory and BIOS. Sometimes, the programme running hangs and we press the ctrl-alt-delete keys simultaneously. This is called Warm Boot. So, when a computer stops responding because of memory problems or the “blue screen of death’’ appears, we need to do a warm boot. The latest operating system Windows 7 responds with task manager when we press the ctrl-alt-delete keys simultaneously. We can choose the not responding programmes to close and continue. However, if the warm boot fails to restart the computer, we need to resort to a cold boot by shutting off the power switch, waiting few seconds and then turning it back on.

CMOS

CMOS is an abbreviation for Complementary Metal Oxide Semiconductor. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits. CMOS uses a complimentary arrangement of NMOS and PMOS, Negative and Positive Metal Oxide Transmitter Circuits. CMOS setup is part of the BIOS program.

Bits and Bytes

A bit refers to binary digit. It is the smallest unit of data in computer, which consists of base 2 digits (i.e. there are only 2 possible values; 0 or 1). There are several units of information which are defined as multiples of bits, such as byte (8 bits), kilobyte, megabyte, gigabyte and terabyte.

1 Byte = 8 Bit
1 Kilobyte = 1,024 Bytes
1 Megabyte = 1,048,576 Bytes
1 Gigabyte = 1,073,741,824 Bytes
1 Terabyte = 1,099,511,627,776 Bytes

What is difference between Bytes, Octets and Nibble? 

The term byte initially meant the smallest addressable unit of memory. In the past, 5-,6-,7-,8-, and 9-bit bytes have all been individual bits (bit-addressed machine) or that could only address 16-or 32-bit quantities (bit-addressed machine). The term byte was usually not used at all in connection with bit- and word-addressed machines. However, term octet always refers to an 8-bit quantity. Today, it mostly used in the field of computer networking, where computers with different bytes widths might have to communicate.

A nibble is a four-bit aggregation, or half an octet. As a nibble contains 4 bits, there are sixteen (24) possible values, so a nibble corresponds to a single hexadecimal digit (thus, it is often referred to as a “hex digit” or “hexit”

Memory

Memory refers to the temporary internal storage areas within a computer. The term memory is usually used as shorthand for ‘physical memory’, which refers to the actual chips capable of holding data. Some computers also use ‘virtual memory’, which expands physical memory onto a hard drive.

RAM

The main type of memory and the most familiar to users is random access memory (RAM).  RAM is the same as main memory.  A computer can both write data into RAM and read data from RAM.

Every time we turn on a computer, a set of operating instructions is copied from the hard disk into RAM. These instructions, which help control basic computer functions, remain in RAM until the computer is turned off. Most RAM is volatile, which means that it requires a steady flow of electricity to maintain its contents.

ROM (read only memory)

Unlike RAM, ROM is non-volatile and only permits the user to read data. Computers almost always contain a small amount of read-only memory that holds instructions for starting up the computer.

PROM (programmable read-only memory)

A PROM is a memory chip on which you can store a program.  Once the PROM has been used, you cannot wipe it clean and use it to store something else.  Like ROMs, PROMs are non-volatile.

EPROM (erasable programmable read-only memory)

An EPROM is a special type of PROM that can be erased by exposing it to ultraviolet light.  EEPROM (electrically erasable programmable read-only memory): an EEPROM is a special type of PROM that can be erased by exposing it to an electrical charge.

PROM, FPROM and ROM

A programmable read-only memory (PROM) or field programmable read-only memory (FPROM) is a form of digital memory where the setting of each bit is locked by a fuse or antifuse. Such PROMs are used to store programs permanently. Read-only memory means that, unlike the case with conventional memory, the programming cannot be changed (at least not by the end user).

Why some data such as picture / videos take more time to copy?

All kinds of data are stored internally as binary digits (bits). Procedure for a copying a file is that the computer first copies the file content as bits from the main memory to its RAM buffer and then to the new location in the main memory. In this procedure there is a criterion that only certain amount of bits can be transferred from main memory to RAM at a time which is mentioned by the block size. Ex: 16-bit, 32-bit, 64-bit computers.

Data files are characters or numbers and thus each require just one byte (8 bits) or two bytes (16 bits) respectively, whereas, image files are stored pixel by pixel (smallest unit in the screen) and thus require more number of bits to store them. Thus during copying as more number of bits must be transferred between the main memory and RAM, the time taken for copying pictures is more than simple data files. Also the time taken for copying the same picture varies from computer to computer depending on the block size.

SRAM v/s DRAM v/s VRAM

Dynamic Random Access Memory (DRAM) is a type of random access memory that stores each bit of data in a separate capacitor within an integrated circuit. Its advantage over SRAM is its structural simplicity; only one transistor and a capacitor are required per bit, compared to six transistors in SRAM. VRAM is a dual-ported version of DRAM formerly used in graphics adaptors. It is now almost obsolete, having been superseded by SDRAM and SGRAM. VRAM has two paths (or ports) to its memory array that can be used simultaneously.

Flash Memory

Flash memory is a form of non-volatile computer memory that can be electrically erased and reprogrammed. Flash memory applications include digital audio players, digital cameras and mobile phones. Flash memory is also used is USB flash drives (Thumb drives, handy drive), which are used for general storage and transfer of data between computers. It has also gained some popularity in the gaming market, where it is often of EEPROM or battery-powered SRAM for game save data.

Keyboard

The standard microcomputer keyboard consists of 104 keys arranged in the standard typewriter or QWERTY layout. A separate numeric keypad is at the right side of the keyboard and can be toggled on or off by pressing the “num lock’’ key. This numeric keypad may not be found in small size laptops and keywords.

QWERTY comes from the first six letters in the top row. It was invented by C L Sholes in 1872.

Mouse

A mouse is a handheld device for moving the pointer around the screen. It is a primary component of the windows GUI (Graphical User Interface) environment. The use of the mouse in windows allows the user to point at and clicks on various icons for programs and data files rather than having to type in commands to copy files, open programs, etc. as in the older DOS.

Data Storage

The area within a computer system where data can be left on a longer term basis while it is not needed for processing is called “Data storage”. The mass storage devices include the diskettes, Hard Drives, Optical Disks and Magnetic Tapes.

Hard Disk

The hard disk is an internal storage device which holds programs and data used by a computer. It consists of magnetic platters with read/write heads that float above the platters to record and play back data.

Compact Discs

Compact Disc (CD) is an optical disc made of several layers of a type of plastic usually Polycarbonates.  The outer layers are protection layers, which simply absorb scratches so that the inner layer holding data remains intact.

DVD

Digital Video Disc or Digital Versatile Disc (DVD) is also an optical storage device that looks the same as a compact disc but is able to hold about 15 times as much information and transfer it to the computer about 20 times as fast as a CDROM. The CD and DVD have the same dimensions.

Blu Ray Disc

Blu-ray, also known as Blu-ray Disc is the name of a next-generation optical disc format that has been jointly developed by the Blu-ray Disc Association (BOA). Blu Ray Disk offers more than five times the storage capacity of traditional DVDs and can hold up to 25GB on a single-layer disc and 50GB on a dual-layer disc.

Monitor

Monitor or visual display unit is the most common output device of a computer. It comprises a display device, circuitry, and an enclosure. The display device in modern monitors is typically a thin film transistor liquid crystal display (TFT-LCD) thin panel, while older monitors use a cathode ray tube about as deep as the screen size. The primitive monitors used the Cathode Ray Tubes (CRTs), until they were replaced by LCD monitors.

Cathode Ray Tube

Cathode Ray Tube (CRT) was invented by German physicist Karl Ferdinand Braun in 1897. It is the device that was long used in most computer displays, video monitors, televisions radar displays and oscilloscopes. The CRT has undergone numerous developments until the advent of plasma screens, LCD, TVs, DLP, OLED displays, and other technologies. Technically, CRT has an electronic vacuum tube employing a focused beam of electrons.

LCD TFT Display

Liquid Crystal Display television (LCD TV) is television that uses LCD technology for its visual output. The technology used is generally TFT. TFT refers to a Thin Film Transistor, which is a special kind of field effect transistor made by depositing thin films for the metallic contacts, semiconductor active layer, and dielectric layer. LCD panels are made of two layers of transparent material, which are polarized, and are “glued” together. One of the layers is coated with a special polymer that holds the individual liquid crystals. Current is then passed through individual crystals, which allow the crystals to pass or block light to create images. LCD crystals do not produce their own light, so an external light source, such as florescent bulb is needed for the image created by the LCD to become visible to the viewer. Thus, LCDs use a strong backlight as the light source and control how much of this light is allowed to reach the pixels by selectively allowing the light to reach each pixel.

Plasma Display Panel (PDP)

We have read above that LCD crystals do not produce their own light, so an external light source, such as florescent bulb is needed for the image created by the LCD to become visible to the viewer. The Plasma television technology is absolutely different from this. The Plasma Display Panel is based loosely on the fluorescent light bulb. The display itself consists of very microscopic cells and within each cell two glass panels are separated by a narrow gap in which neon-xenon gas is injected and sealed in plasma form. Gas is electrically charged at specific intervals and then strikes red, green, and blue phosphors, thus creating a television image. Each group of red, green, and blue phosphors is called a pixel (picture element). Due to presence of its own source of light, PDP suffers from the issues such as heat generation and screen-burn of static images.

EFT monitors

All types of monitors are a strain on our eyes. EFT, or Eye Fresh Technology, monitors have a vital coating on the rear that emits anions and far-infrared rays that serve to make the environment fresh and ease the strain on the eyes and relax the eyes and body.

Working of Touchscreen Monitors

In Touch screen Monitors, we can use our finger on the computer screen to navigate through the contents. This type of screens is most commonly visible in Public Information Kiosks and ATMs. The touch screen has 3 main components as follows:

1. A Touch sensor: It’s a textured coating across the glass face. This coating is sensitive to pressure and registers the location of the user’s finger when it touches the screen.
2. A controller: It is a small PC card that connects the touch sensor to the PC. It takes information from the touch sensor and translates it into information that PC can understand.
3. A Software driver: Software Driver is a software update for the PC system that allows the touchscreen and computer to work together. It tells the computer’s operating system how to interpret the touch event information that is sent from the controller.