CompTIA A+ (220-901 HARDWARE A): Personal Computer Components

Firmware

Firmware is specialized software stored in memory chips that stores OS-specific information whether or not power to the computer is on. It is most often written on an electronically reprogrammable chip so that it can be updated with a special program to fix any errors that might be discovered after a computer is purchased, or to support updated hardware components. Note: Updating firmware electronically is called flashing.

GUID Partition Table (GPT)

GPT is a newer standard that's gradually replacing Master Boot Record (MBR). It's associated with UEFI, which replaces the clunky old BIOS with something more modern. GPT, in turn, replaces the clunky old MBR partitioning system with something more modern. It's called GUID Partition Table because every partition on your drive has a "globally unique identifier," or GUID—a random string so long that every GPT partition on earth likely has its own unique identifier. BIOS/MBR max 4 primary partitions vs UEFI/GBT unlimited (Windows limits to 128) BIOS/MBR partitions max size 2.2 TB vs UEFI/GBT 9.4 ZB

POST Hardware Component & POST Test Criteria

Hardware Component & POST Test Criteria Power supply / Must be turned on, and must supply its power good signal. CPU / Must exit Reset status mode, and must be able to execute instructions. System firmware / Must be readable. System firmware memory Must be readable. Memory / Must be able to be read by the CPU, and the first 64 KB of memory must be able to hold the POST code. Input/output (I/O) bus or I/O controller / Must be accessible, and must be able to communicate with the video subsystem.

Where is the system BIOS stored?

ROM chip

True or False? The GPT is what enables the UEFI to support booting from very large hard disks.

TRUE

The system unit

"The system unit, also commonly referred to as the CPU, or the tower, is the main component of a computer, which houses most of the other devices that are necessary for the computer to function. Traditionally, it comprises a chassis and internal components, such as the system board, the microprocessor, memory modules, disk drives, adapter cards, the power supply, fans and other cooling systems, and ports for connecting external components such as monitors, keyboards, mice, and other devices. System units are also often referred to as boxes, main units, or base units.

Riser Card

A riser card is a board that plugs into the motherboard and provides additional expansion slots for adapter cards. Because it rises above the motherboard, it enables you to connect additional adapters to the system in an orientation that is parallel to the motherboard and thus saves space within the system case. Riser cards are commonly found within rackmount server implementations to provide additional slots for expanding the features of a server and in low rise smaller cases to fit larger expansion cards. Note: A riser card expands motherboard capabilities the way a power strip increases the capabilities of electrical outlets.

What are the minimum requirements for a functioning PC?

Input devices, System unit, and Display device

Volatile and Non-volatile Memory

Memory is considered to be either volatile or non-volatile: Volatile memory stores data temporarily and requires a constant source of electricity to keep track of the data stored in it. When the power is no longer available, the data stored in volatile memory is lost. The computer's main RAM is an example of volatile memory. The computer can both read the data stored in RAM and write different data into the same RAM. Any byte of data can be accessed without disturbing other data, so the computer has random access to the data in RAM. Non-volatile memory retains the information stored on it whether or not electrical current is available. ROM is an example of non-volatile memory.

Cooling Systems

A cooling system is a computer system component that prevents damage to other computer parts by dissipating the heat generated inside a computer chassis. The cooling system can consist of one or more fans and other components such as heat sinks or liquid cooling systems that service the entire computer as well as individual components, such as the power supply and CPU.

Daughter Boards

A daughterboard is type of circuit board that plugs in or is attached to the motherboard or similar expansion card to extend its features and services. A daughterboard is connected directly to the motherboard. Unlike expansion cards, which connect with the motherboard using bus and other serial interfaces, daughterboards are usually directly embedded through soldering. Like a motherboard, a daughterboard has sockets, pins, plugs and connectors to be attached to other boards. Typically, daughterboards are released as a post-launch update to a motherboard or expansion card.

Display devices

A display device is a personal computer component that enables users to view the text and graphical data output from a computer. Display devices commonly connect to the system unit via a cable, and they have controls to adjust the settings for the device. They vary in size and shape, as well as the technologies used.

Power Supply

A power supply is a computer system component that converts line-voltage alternating current (AC) power from an electrical outlet to the low-voltage direct current (DC) power needed by other system components. The power supply is often referred to as the power supply unit (PSU).

Storage Devices

A storage device is a computer system component, such as a hard drive, that enables users to save data for reuse at a later time, even after the personal computer is shut down and restarted. Storage devices can save data magnetically, optically, or electronically, depending on their design.

Peripheral devices

Also called external devices, peripheral devices can provide alternative input or output methods or additional data storage. Common examples of peripheral devices include microphones, cameras, speakers, scanners, printers, and external drives. Of these devices, speakers and printers are output devices; microphones, cameras, and scanners are input devices; external drives are input/output devices.

Expansion Cards

An expansion card is a printed circuit board that you install into an expansion slot on the computer's system board to expand the functionality of the computer.

Input devices

An input device is a personal computer component that enables users to enter data or instructions into a computer. Common input devices include keyboards and computer mice. An input device can connect to the system unit via a cable or a wireless connection.

CPU Components

Arithmetic Logic Unit (ALU) is a component of the processor that performs arithmetic, comparison, and other operations. Control Unit (CU) is the component of the processor that directs and coordinates most of the operations in the computer. Cache Memory

System (BIOS) Basic Input/Output System

Basic Input/Output System (BIOS) is a set of instructions that is stored in ROM and that is used to start the most basic services of a computer system. Every computer has a system BIOS, which sets the computer's configuration and environment when the system is powered on. It is located in ROM chips on the system board. Computers may also include other devices that have their own BIOS to control their functions.

The System Bus

In computer communications, a bus is a group of wires or electronic pathways that connect components. The system bus is the wires, or traces, on the motherboard that provide the main communication path between the CPU and memory. The system bus enables data transfer between the CPU, memory, and the other buses in the computer, which connect other system components such as hard drives and adapter cards. It is sometimes referred to as the frontside bus or local bus.

Memory

Memory is the computer system component that provides a temporary workspace for the processor. Memory refers to modules of computer chips that store data in a digital electronic format, which is faster to read from and write to than tape or hard drives. Memory chips each contain millions of transistors etched on one sliver of a semiconductor. Transistors are nothing more than switches that can be opened or closed. When a transistor is closed, it conducts electricity, representing the binary number 1. When it is opened, it does not, representing the binary number 0.

Which hardware components are checked during the POST?

Power Supply CPU System Firmware System Firmware Memory Memory Input/Output (I/O) Bus or I/O controller

Power-On Self Test (POST)

The Power-On Self Test (POST) is a built-in diagnostic program that runs every time a personal computer starts up. The POST checks your hardware to ensure that everything is present and functioning properly, before the system BIOS begins the operating system boot process. If there is an error, then an audible beep will alert you that something is wrong.

CPU

The central processing unit (CPU) of a computer is a piece of hardware that carries out the instructions of a computer program. It performs the basic arithmetical, logical, and input/output operations of a computer system. The CPU is like the brains of the computer - every instruction, no matter how simple, has to go through the CPU

Computer Cases

The computer case is the enclosure that holds all of the components of your computer. Computer cases come in several sizes and arrangements. Full tower, which is usually used for servers or when you will be installing many drives and other components. Mid tower, which is a slightly smaller version of the full-size tower. Micro, or mini tower, which is the size that replaces the original desktop case in most modern systems. Slim line, which is a tower case that can be turned on its side to save room.

Motherboard

The motherboard is the personal computer component that acts as the backbone for the entire computer system. Sometimes called the system board, it consists of a large, flat circuit board with chips and other electrical components on it, with various connectors. Some components are soldered directly to the board, and some components connect to the board by using slots or sockets.

Types of Memory

There are two types of memory used in computer systems: Random Access Memory (RAM) and Read-Only Memory (ROM). RAM is a computer storage method that functions as a computer's main memory. This type requires a constant power source to access the data stored within the RAM. However, data stored on ROM is saved and stored without a constant power source. Once data is written to ROM, it cannot be modified easily.

Unified Extensible Firmware Interface (UEFI)

UEFI stands for Unified Extensible Firmware Interface, and it is the replacement for BIOS. When a UEFI computer is turned on, it uses what's called a boot manager to look at the current boot configuration. In other words, it checks to see which operating system to boot first. It then loads that operating system and executes the necessary code to get it started up. Much simpler. We skip the extra steps of our multi-stage boot loaders and just boot right from the firmware! BIOS/MBR max 4 primary partitions vs UEFI/GBT unlimited (Windows limits to 128) BIOS/MBR partitions max size 2.2 TB vs UEFI/GBT 9.4 ZB