CompTIA A+ Core Certification: The Basics of IT Hardware Part 1 - Basic Cable Types And Their Connectors, Features, And Purposes

Understanding the physical aspects of computing is an essential requirement for a certified support technician. Although most working technicians become specialized in a few areas of hardware support, it is important to demonstrate a broad knowledge of the different components of computing on the A+ exam.

This guide covers the seven A+ 220-1101 exam objectives related to knowledge of hardware. These objectives may comprise 25 percent of the exam questions:
Core 1 (220-1101): Objective 3.1: Explain basic cable types and their connectors, features, and purposes.
Core 1 (220-1101): Objective 3.2: Given a scenario, install the appropriate RAM.
Core 1 (220-1101): Objective 3.3: Given a scenario, select and install storage devices.
Core 1 (220-1101): Objective 3.4: Given a scenario, install and configure motherboards, central processing units (CPUs), and add-on cards.
Core 1 (220-1101): Objective 3.5: Given a scenario, install or replace the appropriate power supply.
Core 1 (220-1101): Objective 3.6: Given a scenario, deploy and configure multifunction devices/printers and settings.
Core 1 (220-1101): Objective 3.7: Given a scenario, install and replace printer consumables.

As a computer technician, you will need to know how the hardware components of a PC work together and be able to make appropriate hardware choices that best suit a client’s needs. This guide discusses the fundamental hardware topics covered on the CompTIA A+ exam.

Key topics to know:
Basic Cable Types
Network Cables
Ethernet
Fiber
Coaxial
Video Cables
VGA
HDMI
DisplayPort
DVI
Peripheral Cables
Thunderbolt
USB
Peripheral Cables: Serial
Hard Drive Cables
SATA Cables
IDE Cable
SCSI
Adapters
DVI to HDMI
USB to Ethernet
DVI-I to VGA
Connector Types
Installing RAM Types
Virtual RAM
SODIMM Memory
DDR3 SDRAM
DDR4 SDRAM
DDR5 SDRAM: The Current Standard
Single Channel
Dual Channel
Triple Channel
Quad Channel
Parity vs. Nonparity
Error Correction: ECC vs. non-ECC Memory
Installing Memory
Preparations for Installing DIMM Memory
Installing Storage Devices
Optical Drives
CD-ROM/CD-RW
DVD Recordable and Rewritable Standards
Blu-ray Disc (BD)
Drive Speed Ratings
Recording Files to Optical Discs
Hard Drives
Solid-State Drive (SSD)
Magnetic Hard Disk Drives
Speeds/Spin Rate
Form Factors
Hybrid Drives
Flash Drives/Memory Cards
Flash Card Reader
Storage Device Configurations
RAID Types
Creating a SATA RAID Array
Hot-Swappable Drives
Installing Motherboards, CPUs, and Add-on Cards
Motherboard Form Factors
ATX and mATX
ITX Family
Comparing ATX, microATX, and Mini-ITX Motherboards
Motherboard Connector Types
Peripheral Component Interconnect (PCI) Slots
PCIe (PCI Express) Slots
Power Connectors
SATA
eSATA
Headers
M.2
Motherboard Compatibility
Processor Compatibility
Central Processing Unit (CPU) Socket Types
Servers
Mobile
Basic Input/Output System (BIOS)/Unified Extensible Firmware Interface (UEFI) Settings
BIOS/UEFI Configuration
Accessing the BIOS/UEFI Setup Program
UEFI and Traditional BIOS
BIOS/UEFI Settings Overview
Boot Options: Settings and Boot Sequence
Firmware Updates
Security Features
Interface Configurations
CMOS Battery
Encryption
Trusted Platform Module (TPM)
Hardware Security Module (HSM)
CPU Architecture
x64/x86
Advanced RISC Machine (ARM)
CPU Cores: Single Core and Multicore
Multithreading
Virtualization Support
CPU Speeds
Expansion Cards
Installing Sound Cards
External USB Audio Sound Cards
Installing Video Cards
Integrated Graphics Processing Unit (GPU)
Video Capture Cards
Installing Network Cards
Cooling Mechanisms
Fans
Fanless/Passive Heat Sinks
Heat Sink
Phase-Change Material/Thermal Paste
Liquid-Based Cooling
Power Supplies
Power Supply Ratings
Input 115V vs. 220V Multivoltage Power Supplies
20-Pin-to-24-Pin Motherboard Adapter
Output 3.3V vs. 5V vs. 12V
Redundant Power Supply
Modular Power Supply
Multifunction Devices/Printers and Settings
Unboxing a Device/Setup Location Considerations
Appropriate Drivers for the Office Environment
Configuration Settings
Public/Shared Devices
Integrated Ethernet Print/Multifunction Device Sharing
Wireless Device Sharing Options
Using Public and Shared Devices
Using Apps
Maintaining Data Privacy
Network Scan Services
Scanning to Email
Scanning to an SMB Folder
Cloud and Remote Printing
Automatic Document Feeder/Flatbed Scanner
Print Technologies
Laser Printers
Toner Cartridges
Laser Imaging Process
Color Laser Printing Differences
Laser Media Types
Laser Maintenance
Inkjet Printers
Inkjet Components
Inkjet Printing Process
Inkjet Media Types
Inkjet Maintenance
Thermal Printers
Thermal Feed Assembly and Heating Element
Thermal Printer Ribbons
Thermal Print Process
Thermal Paper and Media
Thermal Maintenance
Impact Printers
Impact Components and Print Process
Impact Print Heads
Impact Printer Ribbons
Impact Printer Paper Types
Impact Printer Maintenance
3D Printers
Maintaining 3D Printers

Basic Cable Types
220-1101: Objective 3.1: Explain basic cable types and their connectors, features, and purposes.
The array of cable types in computing can be overwhelming, especially because cable technology is in a constant state of evolution. You need to know not only the kinds of cable, but also different versions of some types. This section organizes cables by their purpose, which should help you keep them straight. Some cables are uncommon and rarely encountered, but you need to be familiar with all the types in this section.

Network Cables
Network cables covered here are different types of Ethernet cable. Ethernet is a term that is commonly used but not often completely understood. Briefly, Ethernet is a system of communication rules that allow computers to work together. Ethernet is considered a networking protocol (which is a bit different from an application protocol). It is concerned with physical cables and wireless standards, as well as the computer’s network interface card (NIC). Ethernet cables are designed to standards that allow the protocols to send and receive messages between devices. Ethernet is not the only communication protocol in use, but it is by far the most common.

Ethernet
Ethernet cable companies are always improving their product. Over time, higher data speeds have been achieved through better engineering of both cables and interface cards. This has created the necessity for categories defining the equipment they can be used with. Between the categories are grades of enhancement that are noted with letters (for example, Cat 5 and Cat 5e, or Cat 6 and Cat 6a).
Ethernet cables carry small voltage pulses (1 is voltage, 0 is no voltage) over a single frequency. This is known as baseband transmission. It is bidirectional, which means that hosts can send and receive data on one cable. The various capabilities are indicated in the cable categories. For example, 1000BASE-T indicates that the cable carries 1000Mb/s on a baseband signal over twisted pair (TP) cables. Cable categories and TP are explained in the sections that follow.
Cat 5, Cat 5e, Cat 6, and Cat 6a

Category 5 (Cat 5), Category 5e (Cat 5e), Category 6 (Cat 6), and Category 6a (Cat 6a) are the most common of the standard cabling grades. They are suitable for use with both standard 10BASE-T and Fast Ethernet networking, and they can also be used for Gigabit Ethernet networks if they pass compliance testing. Cat 6, Cat 6a, Category 7 (Cat 7), and Category 8 (Cat 8) are capable of supporting 10GBASE-T (10GB) Ethernet networks. Cat 8 is capable of supporting 40GBASE-T (40Gb/s Ethernet) over shorter distances, compared to Cat 6 and Cat 7. \

The table below provides the essential information about each of the TP cable types you need to know for the exam.

Categories 5 through 6a are covered on the exam; Categories 3 through 8 are included in Table 3-2 to add perspective. You should know the table well and be able to identify the bandwidth of each category.
 

Table: Categories and Uses for TP Cabling

* Some vendors sold an enhanced version of Cat 6 that they called Cat 6e before the release of Cat 6a. Cat 6e is not an official standard.

No matter how fast they are, all of the copper Ethernet cable categories have a distance limitation of about 100m (about 300 ft.) before the data signal weakens and needs to be boosted by a switch, a hub, or a repeater.

Plenum, PVC, and Direct Burial Cables

Two categories of TP cable exist, in terms of fire rating:
Standard: Standard cable is suitable for patch cables between a NIC and a network jack or in a patch panel. This type of cable typically has a PVC jacket, which can create a lot of smoke when burned.
Plenum: Plenum cable is designed for use in plenum space (that is, space used for HVAC air exchanges), such as in ventilator shafts, under floors, or between suspended ceilings and the permanent ceiling. Plenum cable produces less smoke when burned, produces a lower level of toxic chemicals when burned, and is typically self-extinguishing. Plenum cable jackets might be made from Teflon or from a modified version of PVC that produces less smoke than standard PVC when burned.

Shielded Twisted-Pair (STP) vs. Unshielded Twisted-Pair (UTP)
Twisted-pair (TP) cabling is the most common of the major cabling types. The name refers to its physical construction: four twisted pairs of wire surrounded by a flexible jacket (>unshielded twisted pair, or UTP) or various types of metal foil or braid (>shielded twisted pair, or STP). STP uses the same RJ-45 connector as UTP but includes a metal shield for electrical insulation between the wire pairs and the outer jacket. STP is stiffer and more durable, but also more expensive and harder to loop through tight spaces than UTP. STP is used where electromagnetic interference (EMI) prevents the use of UTP cable.

Figure compares the construction of STP and UTP cables.



An STP Cable (Left) Includes a Metal Shield and a Ground Wire for Protection Against Interference, While a UTP Cable (Right) Does Not

TP and STP cable can be purchased in prebuilt assemblies or can be built using bulk cable and connectors.
Direct burial cables are versions of UTP and STP cables designed with enough protection on the outer jacket (commonly known as a CMX jacket) to withstand weather, ground moisture, and even placement directly in water. The cable can be made to withstand the elements in a few ways. Some are double jacketed, some are filled with a waterproofing gel, and some have a waterproofing tape encasing the twisted pairs. If possible, it is better to run cable through electric conduit, for the most protection. These cables are for normal Ethernet use outdoors with IoT devices or security systems.

T568B (EIA-568B) and T568A (EIA-568A) Standards
The de facto wire pair standard for all types of Ethernet UTP cables is known as >T568B, or EIA-568B. This is the wire order, from left to right when looking at the top of the connector:
Pin 1—Orange/white stripe
Pin 2—Orange
Pin 3—Green/white stripe
Pin 4—Blue
Pin 5—Blue/white stripe
Pin 6—Green
Pin 7—Brown/white stripe
Pin 8—Brown

The T568A (EIA-568A) standard swaps the positions of the orange and green wires used in T568B. This is the wire order, from left to right when looking at the top of the connector:
Pin 1—Green/white stripe
Pin 2—Green
Pin 3—Orange/white stripe
Pin 6—Orange

Figure illustrates cable pairings for a T568B cable, a T568B cable with a vconnector, and a T568A cable.



T568B (Left) and T568A (Right) Wire Pairs and an Assembled T568B Cable

You can create a crossover cable by building one end to the T568B standard and the other end to the T568A standard.

Fiber
Fiber-optic cabling transmits signals with light instead of with electrical signals, which makes it immune to electrical interference. Fiber is more expensive than copper and requires more experience to install, but it offers the benefit of longer distances for large amounts of data and can be used in areas where electrical interference makes copper cable problematic. Because of the expense, fiber is used primarily as a backbone between networks.

Fiber-optic cable comes in two major types:
Single-mode fiber: Has a thin core (between 8 and 10 microns) and is designed to carry a single light ray long distances (60km or farther). Single-mode cable uses a laser diode as a light source. It is typically used by cable TV and telephone companies.
Multimode fiber: Has a thicker core (62.5 microns) than single-mode fiber and carries multiple light rays for short distances (up to 10km). Multimode cable uses an LED light source. It is typically used in local area networks (LANs) and metropolitan area networks (MANs).
An important point to remember about the two fiber types is that single-mode fiber, with its smaller core, carries less data up to 60km (36 miles) before the signal needs to be boosted. Multimode fiber carries much more data, but only for about 10km (6 miles).
Fiber-optic cabling can be purchased prebuilt, but if you need a custom length, it should be built and installed by experienced cable installers because of the expense and risk of damage. Some network adapters built for servers are designed to use fiber-optic cable. Otherwise, media converters are used to interconnect fiber-optic cable to conventional cables on networks.

Fiber-optic devices and cables use one of several connector types. The following are the most common:
Subscriber connector (SC): Uses square connectors
Lucent connector (LC): Uses square connectors
Straight tip (ST): Uses round connectors

These connectors can be used singly or in pairs, depending on the implementation.

Figure illustrates duplex (paired) SC, LC, and ST multimode cables.



SC, LC, and ST Fiber-Optic Cable Connectors Compared

If you need to interconnect devices that use two different connector types, use adapter cables that are designed to match the connector types and other characteristics of the cable and device.

Coaxial
Coaxial cabling is the oldest type of network cabling; its data wires are surrounded by a wire mesh for insulation. Coaxial cables, which resemble cable TV connections, are not popular for network use today because they must be run from one station directly to another station instead of to or from a hub/switch. However, coaxial cabling is used for most cable TV, cable Internet, and satellite TV installations, as well as CCTV cameras used for security.

Legacy 10Mb/s Ethernet Coaxial Cable Standards
Coaxial cabling creates a bus topology. With an Ethernet bus topology, all network members are added to the same physical coaxial cable line to communicate with each other. Each end of the cable must be terminated so that signals are contained. A big disadvantage of the bus is that if any part of the bus fails, the entire network fails.
The oldest Ethernet standard, 10BASE5, uses a very thick coaxial cable (RG-8) attached to a NIC through an AUI transceiver that uses a “vampire tap” to connect the transceiver to the cable. This type of coaxial cable is also referred to as Thick Ethernet, or Thicknet.
 

Thin Ethernet, also referred to as Thinnet, Cheapernet, and 10BASE2 Ethernet, was used for low-cost Ethernet networks before the advent of UTP cable. The coaxial cable used with 10BASE2 is referred to as RG-58. This type of coaxial cable connects to network cards through a T connector that bayonet-mounts to the rear of the network card using a BNC connector. The arms of the T are used to connect two cables, each running to another computer in the network.
If the workstation is at the end of a network, a terminating resistor is connected to one arm of the T to indicate the end of the network. If a resistor is removed, the network fails; if a station on the network fails, the network fails.

Figure shows both of these connection types. Note that some 10Mb/s Ethernet cards are combo cards that might feature both legacy connector types and, on some models, an RJ-45 jack.



Combo UTP/BNC/AUI Ethernet Network Cards (Left and Right), Compared with a UTP/STP-Only Ethernet Card (Center) and Cables

RG-59 and RG-6 Coaxial Cable
Two other types of coaxial cable are common in cable Internet, satellite Internet, and fixed wireless Internet installations:
RG-59: This cable is used in older cable TV and satellite TV installations, as well as in CCTV security installations; it uses 75-ohm resistance. RG-59 uses a 22-gauge (AWG) center conductor and a single outer shield. It is designed for signals up to 50MHz.
RG-6: This cable uses the same connectors as RG-59 but has a larger diameter with dual shielding. It is used in cable TV/Internet, satellite TV/Internet, fixed wireless Internet/TV service, and closed-circuit (security) TV; it uses 75-ohm resistance. RG-6 uses an 18-gauge (AWG) center conductor, which can carry a signal farther than RG-59. RG-6 is also available in quad-shielded versions. RG-6 can carry signals up to 1.5GHz, making it much better for HDTV signals.
 

BNC connectors are used for CCTV cameras and for some types of video projectors. BNC connectors are crimped to the coaxial cable and use a positive-locking bayonet mount.
 

F type connectors are used for cable, satellite, and fixed wireless Internet and TV service. F type connectors can be crimped or attached via compression to the coaxial cable. High-quality cables use a threaded connector. However, some F type connector cables use a push-on connector, which is not as secure and can lead to a poor-quality connection.

Figure compares BNC and F type connectors on an RG-6 coaxial cable.



F Type Connector and BNC Connector on RG-6 Cables

A two-way splitter such as the one shown in Figure 3-6 reduces signal strength by 50 percent (3.5dB) on each connection. Splitting the signal only once usually does not cause issues with your TV or Internet signal. However, if you need to split your signal, contact your TV or Internet provider for a splitter, or ask what type of booster is recommended for your installation.



A Two-Way Coaxial Splitter

Many antennas used for over-the-air digital TV now include a small inline booster that is powered by a 500mA USB connection or a small AC adapter. The booster helps improve range and bring in more stations.

Video Cables
When selecting a monitor or projector for use with a particular video card or integrated video port, it is helpful to understand the physical and feature differences between different video connector types, such as VGA, DVI, HDMI, DisplayPort component/RGB, BNC, S-video, and composite. 
 

Table: Video Connector Types Overview

† HDMI 2.1 or higher
§ DVI-D is digital only; DVI-I supports analog and digital signals; DVI-A is analog only
Single-link
†† Dual-link
‡‡ S-video splits luma and chroma signals for a better picture than composite; composite combines these signals
 

VGA
Video Graphics Array (VGA) is an analog display standard. It is largely a legacy technology, but you might still encounter it on older systems. By varying the levels of red, green, or blue per dot (pixel) onscreen, a VGA port and monitor can display an unlimited number of colors. However, practical color limits are based on the video card’s memory and the desired screen resolution.
The base resolution (horizontal × vertical dots) of VGA is 640×480. An enhanced version of VGA is Super VGA (SVGA), which typically refers to 800×600 VGA resolution.
A VGA card made for use with a standard analog monitor uses a DB15F 15-pin female connector, which plugs into the DB15M male connector used by the VGA cable from the monitor.

Figure below compares these connectors.



DB15M (Cable) and DB15F (Port) Connectors Used for VGA Video Signals

Most video cards with DVI ports use the DVI-I dual-link version, which provides both digital and analog output and supports the use of a VGA/DVI-I adapter for use with analog displays.
The less common DVI-A version supports analog signals only. The maximum length for DVI cables is 5m.

HDMI
Video cards and systems with integrated video that are designed for home theater use support a standard known as High-Definition Multimedia Interface (HDMI). HDMI has the capability to support both digital audio and video through a single cable. HDMI ports are found on HDTVs, as well as home theater hardware such as amplifiers and Blu-ray and DVD players, and many recent laptop and desktop PCs running Windows or Linux. All versions of HDMI support HDCP and digital rights management (DRM) for copyright protection.
The most recent HDMI standard, version 2.1a, supports video resolutions and refresh rates including 8K60 and 4K120, as well as resolutions up to 10K. The most common HDMI port is Type A, which has 19 pins. It is used to achieve high-definition resolutions such as 1920×1080 (known as 1080p or 1080i). For more about HDMI specifications, visit www.hdmi.org.

Mini-HDMI
The HDMI 1.3 and later specifications also define a mini-HDMI connector (Type C). It is smaller than the Type A plug but has the same 19-pin configuration. The HDMI 1.4 specification defines a micro-HDMI connector (Type D), which uses the same 19-pin configuration, but in a connector the size of a micro USB plug.
Regardless of the version in use, HDMI hardware uses connectors similar to the ones shown in Figure and the ports shown in Figure below. Typical cable lengths range up to 40 feet, but higher-quality copper cables can be longer.



HDMI Cable Connectors Compared to DVI and DisplayPort Cable Connectors




HDMI, DVI, and VGA Ports on the Rear of Two Typical PCIe Video Cards


DisplayPort
DisplayPort was designed by the Video Electronics Standards Association (VESA) as a royalty-free digital interface to replace DVI and VGA. It offers similar performance to the HDMI standard.
Unlike HDMI or DVI, which can connect only one display per port, DisplayPort enables multiple displays to be connected via a single DisplayPort connector.
DisplayPort utilizes packet transmission, similar to Ethernet and USB. Each packet transmitted has the clock embedded (whereas DVI and HDMI use a separate clocking signal).
DisplayPort connectors are not compatible with USB, DVI, or HDMI; however, devices that support dual-mode DisplayPort (DisplayPort++) technology are capable of sending HDMI or DVI signals with the use of the appropriate adapter. DisplayPort offers a maximum transmission distance of 3m over passive cable and, in theory, up to 33m over active cable. A DisplayPort connector has 20 pins, with pins 19 and 20 being used for 3.3V, 500mA power on active cables.

The mini-DisplayPort cable shown in the Figure below also uses a 20-pin connector.
DisplayPort cables can be up to 15m long, but quality decreases with length.
shows a high-performance video card with a DisplayPort connector.



DisplayPort, HDMI Port, and DVI Ports

DisplayPort is available in the following versions:
DisplayPort 1.1: Maximum data transfer rate of 8.64Gb/s.
DisplayPort 1.2: Maximum data transfer rate of 17.28Gb/s. Introduces mini-DisplayPort connector and support for 3D.
DisplayPort 1.3: Maximum data transfer rate of 32.4Gb/s, with support for 4K, 5K, and 8K UHD displays.
DisplayPort 1.4: Maximum data transfer rate of 32.4Gb/s. Introduces Display Stream Compression (DSC) 1.2 support.
DisplayPort 2.0: Maximum data transfer rate of 80Gb/s. Introduces support for resolutions beyond 8K, improved configurations for multiple displays, and 4K and beyond for VR.

The Thunderbolt digital I/O interface is backward compatible with mini-DisplayPort, so you can connect mini-DisplayPort displays to either a Thunderbolt or mini-DisplayPort connector. Figure 3-10 depicts various display ports. Thunderbolt is explained further in the upcoming section “Thunderbolt.”

DVI
The Digital Visual Interface (DVI) port is a digital video port that is used by many LED and LCD displays with a 25-inch or smaller diagonal measurement. The DVI-D supports only digital signals and is found on digital LCD displays. Most of these displays also support analog video signals through separate VGA ports.

Figure below depicts DVI-I digital and DVI-D analog cable.



DVI-I Video Port and DVI-D Video Cable

DVI single-link omits some of the connectors in the DVI interface, limiting the maximum resolution. DVI dual-link uses all the connectors, enabling higher resolutions than are possible with DVI single-link.

Peripheral Cables
Cables are highly engineered for the specific tasks they are intended to perform, but the growing number of cable types can become a burden. Designing cables that perform more than one function, such as combining the capability to charge batteries and transfer data, is an option that technology users appreciate.

Thunderbolt
Thunderbolt is a high-speed interface capable of supporting hard disk drives, SSDs, HDTVs up to 4K resolution, and other types of I/O devices. Thunderbolt includes PCIe and DisplayPort digital signals into a compact interface that runs from 2x to 8x faster than USB 3.0, and 2x to 4x faster than USB 3.1 Gen 2. Intel introduced Thunderbolt in 2011. Thunderbolt was initially adopted by Apple, which uses it in the recent and current MacBook product lines. Thunderbolt is also available on some high-end desktop motherboards that use Intel chipsets.
Thunderbolt is available in three versions that use two different port types: Thunderbolt 1 and Thunderbolt 2 use the same physical port as mini-DisplayPort. The newest version, Thunderbolt 3, uses the same physical connector as USB Type C.

All three versions support up to six Thunderbolt devices per port and use daisy chaining to connect devices to each other.
 

Table: Thunderbolt Interface Overview

* Using copper cable. Some vendors are now shipping optical cable in lengths up to 30m.

The figure below compares a Thunderbolt 2 cable with a USB Type C cable (the cable used by Thunderbolt 3) and a mini-DisplayPort cable, which uses the same physical connector as a Thunderbolt cable. USB is explained in greater detail in the next section.



Mini-DisplayPort, Thunderbolt 1/Thunderbolt 2, and USB Type-C/Thunderbolt 3 Cables

Because of Thunderbolt’s high bandwidth, it can be connected to docks that feature multiple port types.

Figure below shows a typical Thunderbolt 2 dock that also provides USB 3.0 ports, an HDMI video port, a Gigabit Ethernet port, and audio headphone and microphone jacks.



A Typical Thunderbolt 2 Dock


USB
Universal Serial Bus (USB) ports have long since replaced PS/2 (mini-DIN) mouse and keyboard ports on recent systems. They can be used for printers, mass storage, and other external I/O devices. Some form of USB port is also used by most mobile devices, game consoles, many network devices, cars and trucks, smart TVs, and other electronics, making USB truly universal.
Most recent desktop systems have at least 8 USB ports, and many systems support as many as 10 or more front- and rear-mounted USB ports. Laptops typically have three or four USB ports, and Windows and Android generally have at least one USB or USB-On-the-Go port.
USB ports send and receive data digitally.

USB-C
The traditional USB Type A (USB-A) has been the standard USB connector for years, but USB Type C (USB-C) is now the industry standard for transmitting power and data. Hundreds of technology companies came together to develop the initial USB-A connector; the same group, known as USB Implementers Forum (USB-IF), has moved forward with >USB-C, a connector that is easier to connect (reversible, with no up or down side to the plug); the appropriate adapter allows backward compatibility to USB 2.0. (USB-C connectors are shown previously in Figures 3-12 and 3-13, and are shown again in Figures 3-15 and 3-16 in the following sections.)
The USB-C standard refers to the connector type on the cable, not the data transfer rate of the cable. USB-C can handle any data rate, from USB-2 to USB-3.2.
USB 2.0, USB 3.0, USB 3.1, USB 3.2, and USB4
 

The following USB ports are included on the A+ certification exam:
USB 2.0 (Hi-Speed)
USB 3.0 (SuperSpeed), also known as USB 3.1 Generation 1
USB 3.1 (SuperSpeed+), also known as 3.1 Generation 2
USB 3.2 Gen 2x2 (SuperSpeed+), rated at 20Gb/s

There are four versions of USB in common use. The industry uses the term Hi-Speed USB for USB 2.0, SuperSpeed USB for USB 3.0, and SuperSpeed+ USB for USB 3.1 Gen 2. USB 1.0 is legacy and is not on the A+ exam.
With any version of USB, a single USB port on an add-on card or motherboard is designed to handle up to 127 devices through the use of multiport hubs and daisy-chaining hubs. USB devices are Plug and Play (PnP) devices that are hot swappable (which means they can be connected and disconnected without turning off the system).

Additional USB ports can be added with any of the following methods:
Motherboard connectors for USB header cables
Hubs
Add-on cards

Some motherboards have USB header cable connectors, which can enable additional USB ports on the rear or front of the computer. Most recent cases also include front-mounted USB ports, which can also be connected to the motherboard. Because of vendor-specific differences in how motherboards implement header cables, the header cable might use separate connectors for each signal instead of the more common single connector for all signals.
USB generic hubs are used to connect multiple devices to the same USB port, distribute both USB signals and power via the USB hub to other devices, and increase the distance between the device and the USB port. Two types of generic hubs exist:
Bus powered: Bus-powered hubs can be built into other devices, such as monitors and keyboards, or they can be standalone devices. Different USB devices use different amounts of power, and some devices require more power than others. A bus-powered hub provides no more than 100 milliamps (mA) of power to each device connected to it. Thus, some devices fail when connected to a bus-powered hub.
Self-powered: A self-powered hub, on the other hand, has its own power source; it plugs into an AC wall outlet. A self-powered hub designed for USB 1.1 or USB 2.0 devices provides up to 500mA of power to each device connected to it, whereas a self-powered hub designed for USB 3.0/3.1/3.2 devices provides up to 900mA of power to each device. USB4 devices provide up to 5A to each device. Note that USB hubs are backward compatible with previous USB versions. A self-powered hub supports a wider range of USB devices than a bus-powered hub.
Add-on cards can be used to provide additional USB ports as an alternative to hubs. One advantage of an add-on card is its capability to provide support for more recent USB standards. For example, you can add a USB 3.0 card to a system that has only USB 1.1/2.0 ports, to permit use of USB 3.0 hard drives at full performance. Add-on cards for USB 1.1 or USB 2.0 ports connect to PCI slots on desktop computers and CardBus or ExpressCard slots on laptop computers, whereas USB 3.0 cards connect to PCIe x1 or wider slots on desktop computers and ExpressCard slots on laptop computers.

This figure illustrates a typical USB 3.0 card, a USB 2.0 self-powered hub, and a USB 2.0 port header cable.



USB 2.0 and 3.0 Hardware


Table : USB Standards Overview

To exceed recommended or maximum cable lengths, connect the cable to a USB hub or use an active USB extension cable.
3m is the recommended length, but no maximum cable length has been established for these versions of USB.
USB 3.2
 

USB 3.2 is actually two standards in one:
USB 3.2 Gen 1 is the new name for USB 3.0 and USB 3.1. Anytime you see a reference to USB 3.2, keep in mind that USB 3.1 Gen 1 and USB 3.0 is the same standard. Although USB 3.1 Gen 1 is the same standard as USB 3.0, vendors continue to use the original USB 3.0 name.
USB 3.2 Gen 2 has new USB 3.1 features. USB 3.2 Gen 2 (often referred to simply as USB 3.2) runs at speeds up to 10Gb/s (2x the speed of USB 3.0/USB 3.1 Gen 1). It is backward compatible with USB 1.1, 2.0, and 3.0/3.1 Gen 1.
Both USB 3.2 Gen 1 and Gen 2 use the same cables and connectors as USB 3.0. However, some USB 3.2 Gen 2 ports support the newer reversible connector, USB Type C, which can be used by both hubs and devices. Some systems, such as the second motherboard similar to the ones shown in Figure below, include both a Type C USB 3.1 port and a standard Type A USB 3.1 Gen 2 port. USB 3.2 Gen 2x2 is available only in the USB Type C connector.



USB 3.0 Standard-B (Left) and Micro-B (Right) Cables and Receptacles

Although USB Type C connectors also support older USB standards, it is unlikely that vendors would use it for USB 3.0, USB 2.0, or USB 1.1 ports.
Other USB standards, such as USB Power Delivery and USB Battery Charging, take advantage of other features in the USB Type C port. For more information about USB 3.2, USB Type C, USB Power Delivery, or USB Battery Charging, see the official USB website, www.usb.org.
illustrates USB 3.0 Type A and Type C cable and USB 3.1 Gen 2 ports.



USB 3.0/3.1 Type A and Type C Ports and Cables

USB4
Although USB4 is not on the A+ exam, it is important to keep up with new technologies and protocols. USB4 was introduced in 2019 and has two versions, USB4 2x2 and USB4 3x2. USB4 2x2 has a maximum data transfer speed of 20Gb/s, and USB4 3x2 has a maximum data transfer speed of 40Gb/s. Both versions are available only in USB Type C connectors.

USB Adapters
USB cable adapter kits enable a single cable with replaceable tips to be used for the following tasks:
Type A male to female, to extend a short cable
Type A female to Type B connectors, to enable a single cable with multiple adapter tips to work with various types of peripherals (see Figure)



USB 2.0 Cable Kit, Including a Type A Male/Female Cable and Several B-Type Connectors

Type A female to USB-On-the-Go, for use with tablets or smartphones (see Figure)



USB-On-the-Go to Type A Adapter, which Enables a Standard USB Cable to Work with Devices That Use the Micro-A Connector

USB to Ethernet, to enable a device without an Ethernet port to connect to a wired network (see Figure)



A Typical USB 3.0 to Gigabit Ethernet Adapter


Peripheral Cables: Serial
In years past, a device connected to a computer via a serial cable plugged into a serial port. >Serial means that the data bits flow in a line, one after the other, over the cable. Serial connections were designed for the relatively low speed of telephone modem communication but were also used for other devices, such as keyboards, mouse devices, and other peripheral devices.
Serial ports and cables were usually compared to parallel ports and cables, where multiple bits flow at once. Serial cables conformed to the RS-232 standard. Printers were the most common devices to be connected with parallel ports, but now most printers are connected with USB cables or via Ethernet cables on networks.
USB cables have replaced serial cables, but it is possible to use a USB-to-serial adapter to connect to an older machine, if necessary.

Hard Drive Cables
Hard drive cables are built to carry data to and from the motherboard. As data rates have increased, cable designs have changed to keep up with the data speeds. This section describes some of the hard drive cables technicians encounter.

SATA Cables
At one time, hard drives were connected to motherboards with Advanced Technology Attachment (ATA) cables. These cables had a ribbonlike appearance, with multiple wires carrying data between the bus and the hard drive.
Serial Advanced Technology Attachment (SATA) cables are next-generation serial cables that carry high-speed data. SATA cables are used inside computer cases and offer not only the advantage of high speed, but also the benefit of better airflow inside the box.
External SATA (eSATA) cables allow for external drives to be mounted at the same data rate. eSATA has better shielding to protect the cable and the data. To prevent the use of thinner SATA cables from being used outside the case, eSATA cables have a different connecter.

Figure below depicts SATA and eSATA cables. (Note the thicker cable and different keying between cables 3 and 4.)



SATA and eSATA Cables Compared


IDE Cable
An Integrated Drive Electronics (IDE) cable is a standard cable type for connecting devices to a motherboard inside a computer case. Older hard drives have IDE connecters, and an IDE cable is one that accommodates them. SATA and SSD storage drives are more common, but you should be able to recognize an IDE hard drive and an IDE connector on a motherboard so that you know whether you need an IDE cable to get them working.
An IDE cable typically has three: one for the motherboard that splits into two connectors. This way, you can attach two hard drives to a motherboard with only one cable.
If you need to service an older computer that has only IDE connectors, but you have a SATA drive, you can solve the problem with a SATA-to-IDE adapter.

Figure depicts a typical IDE connector.



A Typical IDE Cable (Image © Kaspri, Shutterstock)


SCSI
As with their IDE cable cousins, >Small Computer System Interface (SCSI) cables have been replaced by SATA cables inside computers. Most motherboards were designed for SATA and IDE connections, but because SCSI is less common, it requires an >expansion card to connect a hard drive.
The advantages of a SCSI drive system is that up to 7 (or sometimes 15) SCSI drives can be daisy-chained together; for comparison, an IDE connector supports only 2 drives. At one time, SCSI drives were the fastest option, but that is no longer the case: SATA and SSD are faster. On the downside, SCSI was more expensive to purchase and more complicated to configure. Of course, these advantages and disadvantages have been rendered moot by the newer technologies.

Adapters
With any advance in technology, there tends to be a period of time when the old overlaps with the new, or when competing technologies need to find a way to get along. Physical cable adapters are often the short-term (and economical) answer to technical compatibility problems during an upgrade cycle. This section briefly explains the adapters listed in the A+ objectives.

DVI to HDMI
Because HDMI uses the same video signals as DVI, DVI-to-HDMI cables or adapters are widely available. Usually only the video transmits through these adapter cables, but some newer graphics cards allow for HDMI audio over DVI, which eliminates the need for a separate sound cable connection.

USB to Ethernet
USB-to-Ethernet adapters (refer to Figure 3-19) enable a device without an Ethernet port to connect to a wired network. These common connectors are available in a wide range of prices and qualities.

DVI-I to VGA
DVI-I includes both VGA-compatible analog video and DVI digital video. The DVI-I–to–VGA adapters in Figures 3-22 and 3-23 enable VGA displays to work with DVI-I ports on video cards.



Adapters for Mini-DisplayPort and DisplayPort to Other Display Types




Single-Link and Dual-Link DVI-I–to–VGA Adapters


Connector Types
As mentioned earlier, the array of cable types in computing can be daunting. This is even more so with the connector types because many cables can use more than one connector type. To help keep them straight, this section reviews all the networking connector types listed in the A+ objectives. Some of them are legacy types—and they are identified as such—but you might encounter a lot of legacy equipment and, therefore, should be familiar with all the types listed.

Table: Network Connector Types