●【 SYSTEM UNIT 】
The system unit, also known as the system chassis, is a container that ho most of the electronic components that make up a computer system, At one time all system units were in a separate case. Advances in miniaturization of electronic components, however, have led to smaller smaller computers with system units that share containers with other parts the computer system.
As we have previously discussed, a personal computer is the most widely used It is the most affordable and designed to be operated directly by an end user. The five most common types of computers are desktop, laptop, tablet, smartphone and wearable computers. Each has a unique type of system unit.
◆ DESKTOPS
This is the most powerful type of personal computer.Most desktops have their system unit in a separate case. This case contains the system's electronic components and selected secondary storage devices, Input and output devices, such as a mouse, keyboard, and monitor, are located outside the system unit. This type of system unit is designed to be placed either horizontally or vertically. Desktop system units that are placed vertically are sometimes referred to as a tower unit or tower computer.Some desktop computers' manufacturer, like HP. Lenovo and Dell have their monitor and system unit housed together in the same case. These computers are known as an all-in-one.
◆ LAPTOPS
Although typically not as powerful as desktops, laptops are portable and much smaller. Their system units are housed with selected secondary storage devices and input devices (keyboard and pointing device). Located outside the system unit, the monitor is attached by hinges, There are several specialized laptops with features that make them unique. Some of them are:
● Two-in-one laptops, which include a touch screen and the ability to fold flat like a tablet computer. These laptops offer the advantages of a laptop with the convenience of a tablet.
● Gaming laptops, which include high-end graphics hardware and very fast processors. At one time, most gamers preferred desktop computers. As laptops have become more powerful, gaming laptops have become the favourite primarily due to their portability.
● Ultrabook, also known as ultraportables or mini notebooks, which are lighter and thinner th longer battery life than most laptops. They accomplish these advantages by leaving out components such as optical drives and using energy-efficient microprocessors.
◆ TABLETS
Tablets, also known as tablet computers, are the newest and one of the most popular types of computer. They are effectively a thin iab that is almost all monitor with the system unit located behind the monitor Tablets are smaller, lighter, and generally less powerful than laptop computers, Like a laptop, tablets have a flat screen but typically do not have a standard keyboard. Instead, most tablets use a virtual keyboard that appears on the screen and is touch-sensitive. While tablets are very convenient for watching videos or surfing the web, inputting information can be difficult using their virtual keyboard. Some ways to overcome this limitation are with:
● Keyboard attachments. Several manufacturers are offering keyboard options.
For example, HP, Dell and Logitech offer wireless keyboards for tablets.
● Digital pens. These devices assist in selecting options and entering handwritten notes. For example, both Microsoft and Samsung offer tablets with digital pens.
● Speech recognition. This advance feature allows direct verbal communication. For example, both Apple and Google feature excellent speech recognition features built into iOS and Chrome OS.
● Mini tablets are a type of tablet with a smaller screen. While mini tablets operate like a traditional tablet, they typically do not have all the functionality of the bigger tablets. Their most significant advantage is that they are easier to transport in pockets and purses.
◆ SMARTPHONES
Smartphones are by far the most popular mobile device. Designed to comfortably fit into the palm of one hand, smartphones have become the indispensable handheld computer. They greatly extend the capabilities of a cell phone by providing computing power. In addition to capturing and sending audio and video, smartphones run apps, connect to the Internet, and more. Their system unit is located behind the display screen.
◆ WEARABLE COMPUTERS
Wearable computers, also known as wearable devices, are one of the first evolutionary steps to the IoT. These devices contain an embedded computer on a chip that is typically much smaller and less powerful than a smartphones. The most common wearable computers are Smartwatches and activity trackers.
● Smartwatches like Google with android wear. This device acts as a watch, fitness monitor, and communication device. For example, Intex iRist is a smart Watch Phone with Camera. It has space for a SIM and SD card. One can make calls, send messages and download apps.
● Activity trackers like Fitbit Flex. This device monitor daily exercise and sleep patterns. It also connects wirelessly to desktops, laptops, and smartphones to record and share data.
◆ COMPONENT
Personal computers come in a variety of different sizes, shapes, and capabilities. While they look different and each has its own unique features, they share surprisingly similar components, including system boards, microprocessors, and memory.
【 SYSTEM BOARD 】
The system board is also known as the mainboard or motherboard. The system board controls communications for the entire computer system. All devices and components connect to the system board, including external devices like keyboards and monitors and internal components like hard-disk drives and microprocessors. The system board acts as a data path and traffic monitor, allowing various components to communicate efficiently with one another.
On a desktop computer, the system board is typically located at the bottom of the system unit or along one side. It is a large flat circuit board covered with a variety of different electronic components, including sockets, slots, and bus lines.
● Sockets provide a connection point for small specialized electronic parts called chips. Chips consist of tiny circuit boards etched onto squares of sand like material called silicon. These circuit boards can be smaller than the tip of your finger. A chip is also called a silicon chip, semiconductor, or integrated circuit. Chips typically are mounted onto chip carriers. These carriers plug either directly into sockets on the system board or onto cards that are then plugged into slots on the system board. Sockets are used to connect the system board to a variety of different types of chips,including microprocessor and memory chips.
● Slots provide a connection point for specialized cards or circuit boards. These cards provide expansion capability for a computer system. For example, a wireless networking card plug into a slot on the system board to provide a connection to a local area network.
● Connecting lines, called bus lines, provide pathways that support communication among the various electronic components that are either located on the system board or attached to the system board.
Generally, the system board found on a desktop is larger than that found on a laptop, and much larger than one found on a tablet, smartphone, or wearable computer. Although these system boards vary in size, they nevertheless all perform the same function of communicating between the components of the personal computer.
What is system board, and what does it do ?
What are chips ?
How are chips attached to the system board ?
【 MICROPROCESSOR 】
In most personal computer systems, the central processing unit (CPU) or processor is contained on a single chip called the microprocessor. The microprocessor is the "brain" of the computer system. It has two basic components the control unit and the arithmetic-logic unit.
● Control unit: The control unit tells the rest of the computer system how to carry out a program's instructions. It directs the movement of electronic signals between memory, which temporarily holds data, instructions, and processed information and the arithmetic-logic unit. It also directs these control signals between the CPU and input and output devices.
● Arithmetic-logic unit: The arithmetic-logic unit, usually called the ALU, perform two types of operations:arithmetic and logical. Arithmetic Operations are the fundamental math operations: addition, subtraction,multiplication, and division. Logical operations consist of comparisons such as whether one item is equal to (=), less than (<), or greater than (>) the other.
● MICROPROCESSOR CHIPS
Chip processing capacities are often expressed in word sizes, A word is the number of bits (such as 16, 32, or 64) that can be accessed at one time by the CPU. The more bits in a word, the more data a computer can process at one time. Eight bits group together to form a byte. A 32-bit-word bytes at a time. A 64-bit-word computer can access 8 bytes at a time. Therefore, can access 4 the computer designed to process 64-bit words has greater processing capacity. Other factors affect a computer's processing capability including how fast it can process data and instructions.
The processing speed of a microprocessor is typically represented by its clock speed, which is related to the number of times the CPU can fetch and process data or instructions in a second. Older personal computers typically process data and instructions in millionths of a second, or microseconds. Newer personal computers are much faster and process data and instructions in billionths of a second, or nanoseconds. Supercomputers, by contrast, operate at speeds measured in picoseconds—1,000 times as personal computers. In the near future, as fast we can expect processor speeds to be 1,000 times faster than that. operating at speeds measured in femtoseconds.Logically, the higher a microprocessor clock speed, the faster the microprocessor. However, some processors can Nanosecond Picosecond handle multiple instructions per cycle or tick of the Femtosecond clock this means that clock speed comparisons can only be made between processors that work the same way.
At one time, personal computers were limited by microprocessors that could support a single CPU that controlled operations. These computers were limited to processing one program at a time. Now, many personal computers have multicore processors that can provide two or more separate and independent CPUs. For example, a quad-core processor could have one core computing a complex Excel spreadsheet, a second core creating a report using Word, a third core locating a record using Access, and a fourth core running a multimedia presentation all at the same time. More significantly, however, is the potential for Personal computers to run very large, complex programs that previously required expensive and specialized hardware.
For multicore processors to be used effectively, computers must understand e to divide tasks into parts that can be distributed across each core-an operation called parallel processing. Operating systems such as Windows 7 and Mac OS X support parallel processing. Software developers use this technology for a wide range of applications, from scientific programs sophisticated computer games.
● SPECIALTY PROCESSORS
In addition to microprocessor chips, a variety of mon specialized processing chips have been developed.
● Coprocessors are specialty chips designed to improve specific computing operations. One of the most wide used is the graphics coprocessor, also called a GPU (graphics processing unit). These processors are designed to handle a variety of specialized tas such as displaying 3D images and encrypting data. Powerful GPUs are standard feature in gaming computers to support fast processing of virtual environments.
● Many cars have more than 70 separate specialty processors to control nearly everything from fuel efficiency to satellite entertainment and tracking systems
