CACHE MEMORY

 

Unit 01 Overview of Computer System

Computer System

A computer system is a combination of hardware and software components that work together to perform tasks. It includes the physical parts of a computer (hardware) and the programs and instructions that tell it what to do (software).

Key components of a computer system:

·       Hardware:

This refers to the physical components of a computer, such as the central processing unit (CPU), memory (RAM and storage), input/output devices (keyboard, mouse, monitor), and other physical components. 

·       Software:

This encompasses the programs and instructions that tell the hardware what to do. Examples include operating systems (like Windows or macOS), applications (like word processors or web browsers), and other software. 

·       User:

The user is the person who interacts with the computer system to perform tasks. 

·       Data:

The information that the computer system processes, stores, and outputs. 

 

Characteristics

A computer system is characterized by several key features including speed, accuracy, diligence, reliability, versatility, storage capacity, automation, and connectivity. These characteristics enable computers to perform complex tasks with efficiency and precision. 

Here's a breakdown of these characteristics:

·       Speed:

Computers can process data at extremely high speeds, performing millions of operations per second. 

·           Accuracy:

Computers are designed to produce accurate results, minimizing errors in calculations and data processing. 

 

 

·       Diligence:

Unlike humans, computers can work tirelessly for extended periods without losing accuracy or performance. 

·       Reliability:

Computer systems are designed to be dependable and consistent in their operation. 

·           Versatility:

Computers can be used for a wide range of tasks, from simple calculations to complex simulations. 

·           Storage Capacity:

Computers can store large amounts of data for later use. 

·           Automation:

Once programmed, computers can automate tasks, reducing the need for manual intervention. 

·           Connectivity:

Modern computers can connect to networks and other devices, enabling communication and data sharing. 

 

Examples

Include personal computers, desktops, laptops, tablets, hand-held computers, servers, workstations, mainframes, wearable computers and supercomputers

HARDWARE

INPUT HARDWARE

a) Keyboard Based Input

Keyboard-based input refers to the method of entering data, commands, or text into a computer or other electronic device using a physical or virtual keyboard. It is a primary way users interact with computers to input characters, perform actions through shortcuts, and execute system commands.

Keyboard

A computer keyboard is a built-in or peripheral input device modeled after the typewriter keyboard which uses an arrangement of buttons or keys to act as electronic switches. Replacing early punched cards and paper tape technology, interaction via tele printer-style keyboards have been the main input method for computers since the 1970s, supplemented by the computer mouse since the 1980s, and the touchscreen since the 2000s.

Character keys on a keyboard are the keys used to type letters, numbers, punctuation marks, and symbols. These keys are the primary means of inputting text and data into a computer. They include the alphabet keys (A-Z), number keys (0-9), and various punctuation and symbol keys. 

Types of Character Keys:

·         Alphabet keys: These are the letters A through Z, used to type words and text. 

·         Number keys: These are the keys 0-9, used for typing numerical values and in combination with other keys for symbols. 

·         Punctuation and symbol keys: These include keys for common symbols like commas, periods, question marks, quotation marks, and more. 

·         Spacebar: Used to create spaces between words and characters. 

Additional character keys and symbols:

·         Shift keys: Used in combination with other keys to produce uppercase letters or symbols located on the upper part of a key. 

·         Alt key: Used with other keys to produce special characters or perform specific actions, depending on the software. 

·         Control keys (Ctrl): Used in combination with other keys for various functions, often program-specific. 

·         Function keys (F1-F12): Perform specific actions or commands depending on the program or operating system. 

·         Navigation keys: Include arrow keys, Home, End, Page Up, and Page Down, which are used to move the cursor. 

·         Enter/Return key: Used to complete commands or move to the next line when typing. 

·         Backspace/Delete keys: Used to delete characters. 

Keyboards typically have a very similar layout to typewriters, with keys arranged in rows and columns. The specific layout and number of keys can vary slightly between different keyboard models and languages. 

Terminals

A "terminal" can refer to several things, including a physical location (like a bus or train station), a device for interacting with a computer, or a point in an electrical circuit. It can also describe something that marks the end or extremity of something, or something that is related to the end of life. 

Dumb Terminal

A dumb terminal is a device used for interacting with a computer, typically a mainframe or server, that has limited or no processing capabilities of its own. It relies on a host computer to process data and commands, essentially acting as an input/output device. Think of it as a screen and keyboard connected to a powerful central system. 

 

 

 

Here's a breakdown:

·         Function:

A dumb terminal provides a way for users to send commands and receive output from a remote computer. It doesn't perform any calculations or processing locally. 

·         Components:

Typically, a dumb terminal consists of a monitor (screen) and a keyboard. 

·         Historical Context:

Dumb terminals were prevalent in the days of mainframes and minicomputers, where computing power was centralized. 

·         Modern Relevance:

While less common today due to the rise of personal computers and powerful workstations, the concept of relying on a central server for processing is still relevant in technologies like thin clients and virtual desktops. 

·         Example:

In the past, users might have used a dumb terminal to access a database on a central mainframe, with the terminal displaying the results of queries.

 

Intelligent Terminal

 

An intelligent terminal is a computer terminal that can process data locally, unlike a dumb terminal which relies entirely on a central computer. It combines a display and keyboard with at least one built-in microprocessor, enabling features like editing and prompts. Modern intelligent terminals are often based on personal computer technology and are used in various applications, including banking, retail, and industrial data collection. 

Key Characteristics:

·         Processing Capabilities:

Intelligent terminals can perform some data processing tasks on their own, rather than just relaying information to a central system. 

 

 

·         Local Storage (Often):

They may include some local storage, such as a disk drive, for storing data or programs. 

·         Interaction with a Central System:

They can also communicate with and send/receive data from a central processor or larger system. 

·         Examples:

Modern point-of-sale (POS) systems, industrial data collection devices, and some specialized terminals in banking are examples. 

 

b) Non Keyboard Based Input

Non-keyboard based input refers to methods of interacting with a computer or device that don't rely on a traditional keyboard. These methods utilize other input devices to translate user actions into commands or data. Examples include mice, touchscreens, styluses, joysticks, and voice recognition software. 

some common non-keyboard input methods:

·         Mouse:

A pointing device that controls a cursor on the screen, allowing for selection, dragging, and other actions. 

·         Touchscreen:

Allows direct interaction with the screen using fingers or styluses, enabling actions like tapping, swiping, and pinching. 

·         Joystick:

A lever that controls movement in games or other applications, often used for directional input. 

·         Trackball:

A stationary device that uses a rotating ball to control the cursor, offering an alternative to a mouse. 

 

 

·         Tablet and Pen:

A pressure-sensitive surface (tablet) and a stylus that allow for drawing, writing, and other creative input. 

·         Microphone:

Enables voice input for dictation, commands, and other speech-based interactions. 

·         Webcam:

Can be used for gesture recognition, facial recognition, and video input. 

·         Scanner:

Converts physical documents or images into digital data. 

·         Game controller:

A device with buttons, triggers, and analog sticks used for gaming and other interactive applications. 

·         On-screen keyboard:

A virtual keyboard displayed on the screen that can be used with a mouse, touchscreen, or other pointing devices. 

·           Barcode Reader

a printed series of parallel bars or lines of varying width that is used for entering data into a computer system. The bars are typically black on a white background, and their width and quantity vary according to application.

There are majorly 7 different technologies that are used as barcode reader:

Pen Type Barcode Reader - This technology uses a LED Light and a Photodiode at the tip of a pen-like instrument to scan a barcode. The LED light at the tip of the pen illuminates the black and white bars and the light reflected from them is captured by the photodiode that later converts into digital information.

Laser Barcode Reader - This technology also uses LED light and Photodiode, like the pen-type barcode reader. However, the size of the instrument is bigger than the pen type barcode reader. In this technology, a laser beam is shot at the mirror installed on the tip of the instrument. This mirror then moves so that the laser sweeps across the barcode in a straight line. The photodiode then converts the information into digital information.

CCD Readers - Also commonly referred to as LED Scanners, this technology hundreds of LED lights to read and transmit information. This technology reads a barcode in only one go and can work on barcodes of length equivalent to the size of the open end of the device only.

Camera-Based Readers - This technology does not use light to decode information stored in a barcode. It works by taking an image of the barcode that is then used to decode the information through the use of digital decoding techniques. Two major advantages of this technology are that it can be used to read barcode from a distance and it can read a barcode in any manner you keep it.

Cell-Phone Camera - Cell-phone camera with autofocus are ideal for reading barcodes and QR codes. These are commonly used as access control readers where a user can easily scan a barcode or QR code to validate his/her entry to a specific area.

Smartphone - Smartphones nowadays have a camera that supports barcode or QR code scanning. The different operating system also offers unique applications that can be used for the same purpose. Such smartphones are now commonly used at offices and retail stores.