A computer is an electronic device that processes data, performing calculations and executing instructions to accomplish various tasks. It typically includes hardware (physical components) and software (programs and operating systems). A computer system refers to the combination of a computer and its associated peripherals, such as monitors, printers, and storage devices, working together as a cohesive unit to input, process, output, and store information efficiently. In simple words we can say that all these components function together as a single unit to deliver the desired output. A computer system can take different shapes and sizes, ranging from a powerful server to a personal desktop, laptop, tablet, or smartphone.
Figure 1.1 shows a computer block diagram. The arrows indicate how data and signals flow between the components.
Fig 1.1
Central Processing Unit (CPU):
CPU is the electronic circuitry of a computer system that performs the actual processing and is often called the brain of the computer. It is also known as the processor. A CPU is typically found on one or more microchips, known as integrated circuits (IC), which are made of semiconductor materials.
The Central Processing Unit (CPU) receives data and instructions through various programs. Subsequently, the CPU retrieves both the program and data from memory, executing arithmetic and logic operations according to the provided instructions, and subsequently stores the output back into memory.
While processing, the Central Processing Unit (CPU) stores both data and instructions in its local memory, referred to as registers. Registers are integral components of the CPU chip, characterized by their limited size and quantity. Various registers are designated for the storage of data, instructions, or intermediate results.
Other than the registers, the Central Processing Unit (CPU) comprises two primary components — the Arithmetic Logic Unit (ALU) and the Control Unit (CU). The ALU is responsible for executing all arithmetic and logical operations as dictated by the instructions in a program. The CU oversees the sequential execution of instructions, interprets those instructions, and directs the flow of data through the computer’s memory, ALU, as well as input and output devices. The CPU is frequently referred to as a microprocessor.
Input Devices:
The devices responsible for transmitting control signals to a computer are referred to as input devices. These devices are tasked with converting input data into a digital format that is compatible with the computer system. Examples of input devices include the keyboard, mouse, scanner, and touch screen, as illustrated in Figure 1.2. Additionally, specially designed braille keyboards are available to assist individuals with visual impairments in data entry tasks. Furthermore, it is now possible to input data through voice commands; for instance, Google voice search enables users to search the web by vocalizing their search queries.
Fig 1.2
Data entered through an input device is temporarily held in the main memory (commonly referred to as RAM) of the computer system. For long-term storage and future utilization, both the data and instructions are permanently stored in supplementary storage locations known as secondary memory.
Output Devices:
An output device is a tool that receives data from a computer system for display or physical production. It turns digital information into a format that humans can understand. Common examples include monitors, projectors, headphones, speakers, and printers. Figure 1.3 shows several of these devices. A Braille display monitor is especially helpful for people with visual impairments, allowing them to read text output from computers.
Fig 1.3
A printer is a common device used to produce physical copies of documents (hardcopy). The main types of printers today are inkjet, laser, and dot matrix printers. Recently, a new type called the 3D printer has come into use, allowing for the creation of physical models from digital designs. These printers are increasingly used in manufacturing to make product prototypes and are also being explored in medicine for creating body organs.
