Key Components:
- Summarize the characteristics of computing systems from the first to the fourth generation.
- Vacuum Tubes – first gen
- Transistors – second gen
- Integrated Circuits – third gen
- Microprocessors – fourth gen
- Artificial Intelligence – fifth gen (future) (also Quantum Computing and Nanotechnology)
- Identify the difference between scripting and programming languages.
- Differentiate between input, output, and storage.
- Define system.
- Identify components of computer hardware.
- Differentiate between motherboard components, their purposes, and their properties.
- Describe the role of a central processing unit (CPU) in a computing environment.
- Classify peripherals by their role (input, output, temporary memory, storage).
- Identify computer peripherals.
- Identify the categories of computers according to their components and capabilities.
- Identify storage and input/output (I/O) systems including different media and file systems.
Computer Hardware and History
The Abacus
- The abacus is a device that stores values represented by the position of the beads on the rods. The human operator carries out mathematical operations by moving the beads.
The Leibniz Machine
- More sophisticated computing machines emerged between the Middle Ages and the Modern Era when a few inventors began to experiment with the technology of gears. These machines represented data through gear positioning. The data was initially entered by mechanically positioning the gears in a specific gear position. The final gear position represents the output of the calculations.
The ENIAC
- (Electronic Numerical Integrator and Calculator)
- The idea of communicating instructions with punched cards originated in 1801 in a system specifying the steps of the weaving process. Different patterns of holes resulted in different woven designs.
The central processing unit (CPU) is the electronic circuit responsible for executing computer program instructions. The CPU consists of three parts:
- the arithmetic logic unit (ALU), which contains circuitry that performs operations on data (such as addition and subtraction);
- the control unit, which contains the circuitry coordinating the machine’s activities; and
- the processor register, which contains data storage cells called registers.
CPU
The central processing unit (CPU) is the electronic circuit responsible for executing computer program instructions. The CPU consists of three parts:
- the arithmetic logic unit (ALU), which contains circuitry that performs operations on data (such as addition and subtraction);
- the control unit, which contains the circuitry coordinating the machine’s activities; and
- the processor register, which contains data storage cells called registers.
Registers are high-speed storage areas in the CPU. All data must be stored in a register before it can be processed. They serve as temporary holding places for data being manipulated by the CPU. Registers hold the inputs to the ALU and store the results. To perform an operation on data stored in the main memory, the control unit
- transfers the data from the main memory into the registers,
- informs the ALU which registers hold the data,
- activates the ALU, and
- tells the ALU which register should receive the result.
Figure. Example of a CPU.
| Memory address register (MAR) | Holds the memory location of data that needs to be accessed |
| Memory data register (MDR) | Holds data that is being transferred to or from memory |
| Accumulator (AC) | Holds the ALU results |
| Program counter (PC) | Holds the address of the next program instruction to be executed |
| Current instruction register (CIR) | Holds the current instruction during processing |
RAM
Memory/Mass Storage
The memory unit consists of random-access memory (RAM), sometimes referred to as primary or main memory. Unlike a hard drive (permanent memory, secondary memory), this memory is fast and directly accessible by the CPU. Loading data from secondary to primary memory allows the CPU to operate faster. However, RAM is ephemeral, meaning data stored in RAM is lost when the computer is powered off.
RAM is split into partitions. Each partition consists of an address and its contents, all in binary form. The address uniquely identifies every location in the memory.
In addition to RAM, read-only memory (ROM) is another component that stores instructions for crucial system activities, including booting up the system and initializing different computer components.
Peripheral Devices
Various units that support the input and output functions are collectively called peripheral devices and comprise the I/O unit. Input devices, such as keyboards, mouses, and sensors, are used to move data into computers. Output devices, such as printers and monitors, are used to move information out of computers.
Buses or bus lines are the wires that serve as electrical roadways, transmitting information between the CPU and other components. The size of the bus is related to the amount of data that can be transmitted at once. Instructions are sent through the bus lines to the CPU and include how to process the data and which component to use. These instructions are split and sent through three different types of buses: address buses, data buses, and control buses.
Buses Diagram
Figure. Buses as data paths of a computer system.
| Address bus | Carries the destination address of where the data is assigned to be processed |
| Data bus | Carries data between the processor, the memory unit, and the input/output devices |
| Control bus | Carries control signals (commands) from the CPU (and status signals from devices); controls and coordinates all activities within the computer system |
The System Unit
The system unit, also known as a tower or chassis, encases various components already mentioned: the motherboard, CPU, RAM, power supply, and any other internally installed components. The term system unit is often used to differentiate between the computer and its peripheral devices.
Components of the System Unit
The Motherboard
Again, the motherboard is the main circuit board for the computer containing both soldered components that cannot be removed and sockets or slots for components that can be removed. The motherboard holds the CPU, RAM, and ROM chips, as well as other hardware components. RAM stores instructions and data while they are being used. This storage is volatile, which means when the system is turned off, the contents in RAM are lost. Unlike RAM, ROM chips are nonvolatile memory, keeping their content whether the system is on or off, and generally contain instructions for starting up the computer.
Computer Processing Unit (CPU)
You have already learned that the CPU is the brain of the computer. It executes instructions and tells other components what to do.
The System Clock
The system clock sends out a pulse of electricity at regular intervals. The electronic components of the computer need these electric pulses in order to operate. The more pulses sent out by the system clock, the faster the computer. One instruction gets processed per pulse. Multiple processing units and a higher clock speed increase the processing speed of the computer system. The system speed commonly is measured in two primary measurements:
- megahertz (MHz), which converts to millions of pulses per second
- gigahertz (GHz), which converts to billions of pulses per second
Expansion Slots
Expansion slots are sockets on the motherboard where expansion cards can be installed. Common types of expansion cards include graphics, sound, and network cards.
Ports
Ports are sockets that allow cables to be plugged in without opening the system unit. Some examples are serial, parallel, and Universal Serial Bus (USB) ports, which are recognizable by their distinct shapes.
Secondary Storage
Secondary storage devices hold data and information permanently. Secondary storage devices store data and instructions while they are not being used; the saved content remains on the secondary storage unit even when the computer is powered down. There is a variety of secondary storage types, including floppy and hard drives, flash drives, magnetic tape, and optical discs, such as CDs and DVDs.
A bit is the smallest unit of storage that is set to 0 or to 1. Bits need to be combined to create a useful representation of data or information; a group of eight bits forms a byte. A byte contains enough information to store a single character, such as the letter “M.”
| Activity Write your name in binary using the ASCII code via this text-to-binary tool: https://www.rapidtables.com/convert/number/ascii-to-binary.html |
Computer Storage and Memory
Computer storage and memory are often measured in megabytes (MB), gigabytes (GB), and terabytes (TB). A medium-sized novel contains about 1 MB of information. 1 MB is 1,024 kilobytes, or 1,048,576 (1024×1024) bytes, not one million bytes. However, you may find documents that estimate each MB to 1,000 KB. When planning storage requirements, be sure to verify the accuracy of the documented storage capacity. Similarly, 1 gigabyte (GB) is 1,024 MB, 1 terabyte (TB) is 1,024 GB, and 1 petabyte (PB) is 1,024 TB. For another point of reference, 1 TB is roughly equivalent to 1,500 CDs worth of data, and 1 PB of data would create over 1.5 million CDs, a stack a mile high.
| Unit | Equivalent in Bytes |
| 1 kilobyte (KB) | 2^10 or 1,024 bytes |
| 1 megabytes (MB) | 2^20 or 1,048,576 bytes |
| 1 gigabytes (GB) | 2^30 or 1,073,741,824 bytes |
| 1 terabyte (TB) | 2^40 or 1,099,511,627,776 bytes |
| 1 petabyte (PB) | 2^50 or 1,125,899,906,842,624 bytes |
Input Output Devices
Input devices translate data into a form that the computer can understand, and output devices translate information into a form that humans can understand.
The keyboard is the most common input device. Direct input devices such as pointing devices (mouse and trackball) and scanning devices (bar code readers) are much faster and have less room for error compared to the keyboard. Styluses, cameras, and microphones are input devices more commonly used in smartphones.
Monitors and printers are the most common output devices. Monitors present the output on a screen, and printers produce hard copies on paper. Other examples of output devices include speakers, 3D printers, and projectors.
Identify the I/O devices attached to the system unit of the machine you are using. Consider how each device supports your communication with the computer system.
Communication Devices
Communication devices allow a computer to send and receive data to and from other computers. Modems send information over a phone line or coaxial cable, whereas a network card sends information over dedicated network cables. Satellite, wireless, and Bluetooth technologies enable data to be transmitted without the need for physical wires. Satellite communication uses radio signals and orbiting satellites to receive and send data from one system to another. Bluetooth adapters facilitate wireless communication between electronic devices. Common devices that use Bluetooth include hands-free earpieces, wireless keyboards, mouses, and microphones.
Types of computers
Input devices translate data into a form that the computer can understand, and output devices translate information into a form that humans can understand.
The keyboard is the most common input device. Direct input devices such as pointing devices (mouse and trackball) and scanning devices (bar code readers) are much faster and have less room for error compared to the keyboard. Styluses, cameras, and microphones are input devices more commonly used in smartphones.
Monitors and printers are the most common output devices. Monitors present the output on a screen, and printers produce hard copies on paper. Other examples of output devices include speakers, 3D printers, and projectors.
Identify the I/O devices attached to the system unit of the machine you are using. Consider how each device supports your communication with the computer system.
Communication Devices
Communication devices allow a computer to send and receive data to and from other computers. Modems send information over a phone line or coaxial cable, whereas a network card sends information over dedicated network cables. Satellite, wireless, and Bluetooth technologies enable data to be transmitted without the need for physical wires. Satellite communication uses radio signals and orbiting satellites to receive and send data from one system to another. Bluetooth adapters facilitate wireless communication between electronic devices. Common devices that use Bluetooth include hands-free earpieces, wireless keyboards, mouses, and microphones.
Types of Computers
Computers are categorized based on their size and processing speed.
Supercomputers are the biggest and fastest computers, designed to process huge amounts of data. They are built as a system of thousands of interconnected processors. Supercomputers are particularly useful in scientific and engineering applications such as weather forecasting, scientific simulations, and nuclear energy research.
Mainframe computers are designed to support hundreds or thousands of users simultaneously. They also support multiple programs at the same time, making them useful to big organizations that manage and process high volumes of data.
A workstation is a single-user computer designed for technical or scientific applications. It has a faster microprocessor, a large amount of RAM, and high-speed graphics cards. It generally performs a specific job with great expertise. Graphics, music, and engineering design departments often use this type of system.
A microcomputer is more commonly known as a personal computer. It is a general-purpose computer for individual use. It has a memory, storage, input and output units, and a microprocessor as a central processing unit. Desktops, laptops, and handheld or mobile devices are all microcomputers.
Device Types
Click to read more about components and their definitions.