Page 3 901 Hardware Study Guide for the CompTIA® A+ exam

PC Connection Interfaces

PCs offer many different connection types, as they interact with a multitude of devices. You should be able to compare and contrast the following connections:

Physical Connections

  • USB 1.1: first widely used version; low speed of 1.5 Mbps and full speed of 12 Mbps
  • USB 2.0: speed increase to 480 Mbps; maximum cable length of 5 meters
  • USB 3.0: speed increase to 5 Gbps; known as SuperSpeed USB; maximum cable length of 3 meters
  • USB Connectors: A type connects to a computer; B type connects to a peripheral, such as a printer; mini and micro connect to smaller mobile devices such as cell phones or tablets
  • Fireware 400: IEEE 1394a standard popularized by Apple; Alpha mode; 100, 200, or 400 Mbps maximum speed
  • Fireware 800: IEEE 1394b standard; Beta mode; 800 Mbps maximum speed
  • SATA1: maximum speed of 1.5 Gbps; maximum length of 1 meter
  • SATA2: maximum speed of 3 Gbps; maximum length of 1 meter
  • SATA3: maximum speed of 6 Gbps; maximum length of 1 meter
  • eSATA: external SATA connection; same speed as SATA designation being used, with maximum length of 2 meters
  • VGA: 15-pin blue connector used for video; known as a female DB-15 connector; analog signal
  • HDMI: all digital connection capable of sending video and audio
  • DVI: capable of sending analog or digital and supports single/dual links
  • Audio: analog audio uses a TRS end; digital audio uses TOSLINK end (optical)
  • RJ-45: four-pair network cable used for ethernet applications
  • RJ-11: two-pair cable, typically used for phone lines and analog connections
  • Thunderbolt: high-speed serial connection; sends data and power on same cable

Wireless Connections

  • Bluetooth: class 1 for industrial use, with maximum distance of 100 meters; class 2 for mobile use, with max distance of 10 meters; class 3 for special usage, with a maximum distance of 1 meter
  • RF: encompassed into the 802.11 standards for wireless communications; operates at varying frequency levels
  • IR: infrared technology using up to 4 Mbps; line of sight needed; maximum distance of 3 feet
  • NFC: short-range technology; speeds of 106, 212, or 424 Kbps; distance around 10 centimeters


These are some things you need to remember when choosing connections:

  • Analog signals are typically lower frequency audio signals. Analog is prone to interference (noise) that distorts the signal.
  • Unlike analog signals, digital signals are sent using a binary signal of zeros and ones. The advantage of digital signalling over analog is the ability to eliminate noise. Digital can easily be compressed, and it uses less storage.
  • Various transmission mediums have different limitations on recommended distance. This is typically published within the standard for ethernet, fiber, wireless, etc.
  • Transfer speed deals with how much information you can send through the communication medium at a given time. It is measured typically in bytes or bits, depending on the technology. It is commonly called throughput.
  • Quality is the ability to faithfully reproduce a signal, typically an attribute of voice communication. Be aware of sample rates when dealing with analog to digital conversion.
  • Understand the various frequencies used in wireless transmission. Lower frequency devices can be easily interfered with by cordless phones, garage door openers, and baby monitors. Lower frequency transmission has the advantage of range over higher frequencies, but higher frequency has the advantage of greater bandwidth (throughput)

Power Supply

The majority of computing components require some sort of power to be able to operate. You should be familiar enough with the power specifications and connectors to install components based on specific requirements.

Connector Types/Voltages

  • SATA: 3.3V, 5V and 12V specifications; specialized
  • Molex: 5V and 12V specifications; general type
  • 4/8-pin 12V: called ATX 12V or EPS 12V; provides 12V accordingly
  • PCIe 6/8-pin: 6-pin provides 75W, and 8-pin provides 150W of 12V.
  • 20-pin: 20/24-pin is likely largest power connector; provides 3.3V, 5V, or 12V specifications
  • 24-pin: designed to be backward compatible with 20-pin; provides 3.3V, 5V, or 12V specifications


Various specifications are also important in power supply selection. Here are some of them:

  • wattage: like horsepower, the ability to do work; power rated in watts, which is the product of current times voltage (A 5-volt power source providing 10 amps of current would be delivering 50 watts of power.)
  • dual rail: has two 12V rails inside of the power supply for connections on independent circuits
  • size of power supplies: fairly standard, unless running a custom setup; check documentation from manufacturer in this case
  • number of connectors: may be permanently affixed to the power supply or they may plug in or be combination of both
  • ATX: a standard size case; should be able to handle most size power supplies
  • microATX: designed to be as small and efficient as possible; may require a specialized power supply; older power supply may not fit
  • dual voltage: able to switch between 100V and 240V, either manually or automatically

Selecting PC Components

Being able to select the proper components to fulfill a particular PC build is critical. Given a set of requirements, you should be able to design the appropriate computer to suit the customer.

Graphic/CAD/CAM Design

  • multicore processor: needed for performing calculations needed for designs and modeling
  • high-end video: needed to assist with processing the high quality graphics
  • maximum RAM: enables all of the graphics programs to run smoothly; all usage needs benefit from plenty of RAM

Audio/video Editing

  • specialized audio and video card: needed to be capable of handling the video editing on the fly
  • large fast hard drive: needed when video files are very large to see more responsive memory from a larger drive or SSD
  • dual monitors: good so that you can work simultaneously on multiple parts of the editing needed and also view changes with minimal effort


Maximum RAM and CPU cores are very beneficial, as they make the process more efficient when dealing with multiple machines and systems. Sizeable RAM and CPU cores can be dedicated to the virtual machines.


  • Multicore processor: Because games require a lot of processing, multiple cores will help increase the efficiency.
  • High-end video/specialized GPU: High-end video will ensure that you are able to support the intensive graphics requirements of modern games.
  • High-definition sound card: A great sound card will enable you to get the most out of the sound from your games, which is usually very elaborate.
  • High-end cooling: Good cooling is a necessity, as most modern games are taxing your computer resources the entire time. This will help keep everything running optimally.

Home Theater

  • Surround sound audio: For a theater PC, the surround sound experience is important, just like in a true movie theater.
  • HDMI output: Being able to support HDMI is essential for high-definition video like in a theater.
  • HTPC compact form factor: A small form factor is important to be able to store the system in a common place, like next to the TV stand.
  • TV Tuner: This will enable you to save videos that you are viewing to the local system for playback at a later date.

Standard Thick Client

  • desktop applications: uses traditional programs and applications like a standard PC
  • OS requirements: specifications to confirm the type of CPU and memory requirements recommended

Thin Client

  • basic application: Only the bare minimum applications needed for a thin client, as the primary applications are stored on another computer.
  • OS requirements: Again, only the bare minimum is needed to support the OS, as the workload is being done in another location.
  • Network connectivity: Since most of the applications will be delivered over the network, it is important to have a high-speed network connection for increased efficiency.

Home Server

  • media streaming: can be used as a place to centrally store movies or music
  • file sharing: can be used as a place to centrally store documents
  • print sharing: can be used as a place to have a central printer, accessible by everyone
  • gigabit NIC: high-speed ethernet connection supported by nearly all new systems required for video streaming
  • RAID array: ideal to set up to ensure no data is lost in the event of a hardware failure