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marmont | CompTIA A+ | Module 1.7 - Compare Connection Interfaces

By: marmont | Related Course: CompTIA A+ | Published: June 14, 2016 | Modified: July 8, 2016
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NotepadAnalog vs Digital and Parallel vs Serial

There are various ways to transport data through cables, and there are two major distinctions to look at, and those would be, Analog vs Digital and Parallel vs Serial.

Analog cables transmit signals via waves whilst Digital transmits via bits (1’s or 0’s), you can find connectors for analog to analog devices or digital to digital devices because the data that travels through them is the same, but when it come to converting from one to the other it is a bit harder (no pun intended), because the data is different, therefore you must buy a converter which converts from analog to digital or from digital to analog, depending on the case.

Another distinction between cable signals is, the parallel vs serial distinction, what serial does is it send information one bit at a time in packages, so there is a start bit followed by the information, followed by a stop bit, then there is a pairity but which basically checks that the information is being transmitted and that everything is okay, the information goes from the CPU through a SATA cable straight to the hard drive, when you talk about a Parallel transmition you refering to a signal that transmits 8 bits at a time all simultaneously across the connectors, from the CPU to the hard drive through a PATA cable. Theoretically it would make more sense to mantain the PATA cable than to move to the SATA, but there are several issues, first being that the PATA has several more pins, a SATA has 7 pins whilst the PATA has 40 pins and is an 80 wire connector, the timing has to be a lot more precise because the PATA has to send 8 bits at a time, therefore giving it more room for error, and causing EMI (Electro-Magnetic Interference) to have a greater effect on the PATA.

NotepadAudio Cables

Audio Cables:

These are the cables used to recieve and transmit audio, these come in several variants including:

  • 1/8 Inch Stereo Cable: It is an analog cable and is the most common cable used, It comes in stereo and.
  • HDMI: It is a digital cable that transfers and recieves both video and audio.
  • MIDI(Musical Instrument Digital Interface): This is most prevalent on external instruments that you are trying to connect to a computer, they can be daisy chained, it looks similar to the PS/2 cable types.
  • Coax S/PDIF(Sony/Phillips Digital Interface): It is a standard for digital audio tranfer.



Bluetooth is a short-range wireless connection, with a range of about 10 meters, usually this isn’t an issue because you’re using it in your car with a headset or with your phone in your pocket, for the most part bluetooth is built-in on laptops and phones, but sometimes especially with desktops and older laptops it wont have bluetooth built-in, in this instance there are various USB bluetooth adapters which allow the computer to recieve and transmit bluetooth connections, typically pairing two devices isn’t much work, you set your computer to discover devices, choose the device to pair, most times a code will appear that you need to type on your computer, and they are synced, after syncing, sometimes your device will automatically sync such as when you pair your phone and car, when it comes into range. Bluetooth transmits at a frequency of 2.4 GHz, this frequency is frequently used for transmitting wirelessly.

NotepadHDMI Cables

HDMI (High-Definition Multimedia Interface) Cables:

The main factor that separates HDMI from the other cables seen before, is that it doesn’t only provide digital video, but it also provides digital audio, the reason for this being an advantage is that if you wish to connect a laptop, DVD player, or computer to a larger screen, the additional audio cables are unnecessary. It has become common in Blu-Ray players, Video Game systems, large TV’s, Laptops, etc, because it makes the connection a lot easier. It comes in 4 variants:

  • Type A-19 pin-1080p resolution
  • Type B-29 pin-3840X2400
  • Type C-19 pin-Mini HDMI
  • Type D-19 pin-Micro HDMI


NotepadInfrared & Radio Frequency

Infrared & Radio Frequency:

Infrared actually communicates through light that is on the light spectrum, but is invisible to the human eye, because it works with light there are some differences when it comes to

NotepadParallel/LPT Cables

Parallel/LPT Cables;

Once again a Parallel cable isn’t refering to the type of data transfer but instead to the LPT (Line Printer) cable they have a recommended 10 meter max. length, but if you have a shielded LPT cable you could move that max. length up to 25 meters. They come in two variants:

  • IEEE-1284a: It will be the computer end port, a DB-25F .
  • IEEE-1284b: It will be the port that’s on the printer side, A Centronics connector, which is a 36 edge connector.

there are two other types of connectors which will be the switchbox connectors which are a-a, and the data transfer cables which are a-a aswell, but the cable will have a twist in it.

NotepadPS/2 Ports


they are what we’ve more recently used for keyboards and mice, but they are slowly being fazed out by USB cables, although they are still seen on computers used today, they can be handy because when you plug a keyboard or mouse into a PS/2 port you won’t need to install additional drivers, of course if the keyboard has special functions, said functions may need drivers in  order to be used. The cables and ports come color coded, Purple being for the keyboard, and Green being for the mouse, they are color coded because both ports look identical, typically the mouse port will be on top and the keyboard port will be below the mouse one. when connecting the cable you must make sure to connect the cable to the port while the computer is off.


NotepadRJ-11 Cable

RJ-11 cable:


RJ-11 is similar to the RJ-45 cable, but it has less pins, as well as less wires, RJ-11 stands for Register-Jack-11 and it has 6 connectors and 6 wires, side by side the RJ-11 is visibly smaller than the RJ-45, and obviously has a much smaller port. They were used when we tried to connect our modems through our telephone lines but now our internet cables use RJ-45. On the inside it is quite different from the RJ-45 cables, both cables do carry power across them, there have been instances where they are assumed to just be data lines, and have been handled as such, and have given the user an electrical shock.

NotepadRJ-45 Cables

RJ(Register Jack)-45 Cables:

It has 8 wires, and is used for internet connections (ethernet), it is color coded and has two different types of color patterns which are, T568A, and T568B, the two types of color codes are really just to keep things standard. The RJ-45 is refered to as a UTP (Unshielded Twisted Pair) type cable, the twist is to reduce electro-magnetic interference throughout the cable, if the twist weren’t to exist the cable would have to be considerably shorter. They come in many variations, but there are only 5 that you’ll be dealing with on a day to day basis, them being:

  • Cat 3: It has a max. transfer speed of 10 mb(megabits)s, and it runs at 16 MHz
  • Cat 5: This one allows for a max. transfer of 100 mb(megabits)s, and runs at 100 MHz, and can run a different mode called ATM (A-synchronous transfer mode) this allows for it to run at 155 MHz, this isn’t ussually for home usage as it only runs from one ATM switch to another, so it used mostly by internet service providers to provide faster internet speeds.
  • Cat 5e: 100 Mbs-100MHz-ATM(155 MHz)
  • Cat 6: 1 Gbs-250Mhz-ATM(155MHz)
  • Cat 6a: 10 Gbs-550 MHz

In order to upgrade you must upgrade the cables and everything the cables connect to.

When you are pushing power over an ethernet port, it is refered to as POE(Power Over Ethernet).`

NotepadSATA & IDE/PATA Cables

SATA(Serial Advanced Technology Attachment):

It is a 7 pin cable that has a min. length of 12” and a max. length of 1 metre, if the cable is shorter than the minimum 12” there will be issues with the connection, the SATA comes in 4 variants that are identical but have different Data Rates, these are:

(All rates are expressed by Giga Bits per Second)

  1. SATA1-1.5 Gbs
  2. SATA2-3.0 Gbs
  3. SATA3-6.0 Gbs
  4. eSATA(External SATA)-5.0 Gbs

SATA is a 1-1 port to device cable so it cannot be ”Daisy-Chained” like USB and Firewire can.



IDE/PATA(Parallel Advanced Technology Attachment)

it has 40 pins, and comes in two variants:

(All speeds are expressed in Mega bits per second)

  • 40 cable version-100 Mbs
  • 80 cable version-133 Mbs

Nowadays the 80 wire cable is more prevalent because it helps for it to have better connection, less crosstalk and a faster connection, because of the number of wires in the cable.

The max. length is 18”.

NotepadSerial Cable

Serial is the word used when you are refering to connection that transfers bit after bit consecutively. A Serial Cable can also be called a COM Cable, so when refering to a ”Serial Cable” it will be understood as a COM cable even though a SATA cable or a USB cable could also technically be refered to as a ”serial” cable.

The Serial/COM/RS-232 cable was originally used to connect printers, mice, cameras, etc, some of their uses are being fazed out as we move on to better connections, such as, mice which are leaning more towards using USB connections, but the Serial Cable is still a useful cable to get to know, the Serial cable is a 1-1 cable which means the you can only connect one device to each cable. The Serial Cable comes in 2 variants which are:

  • DB-9F: it has 9 pins as you can see by the name, and the F stands for female.
  • DB-25F: it has 25 pins and like the above the F stands for female.

The ports will be refered to the same just with an M for male instead of an F.

The cable will use at least three wires which are called:

  1. Transmit Wire
  2. Receive Wire
  3. Signal Wire

The pins don’t come configured the same way on each given cable, meaning that you can’t say for certain the one pin is for Transmition, or the other is for Recieving, some Serial Cables for instance come with a twist in them which means that at a certain point the wires cross-over, these are when connecting two computers together, some are straight cables where one pin connects straight to the other side to the other pin. Serial Cables also come into in different lengths which is due to the fact that they transmit data at different rates, when the cable transmits at a slower rate it allows for the max. length to be longer whilst when the cable transfers at a faster rate the cable must be shorter to prevent data loss.

NotepadVGA & DVI Cables

VGA & DVI Cables:

Both are Video cables, cables used to connect a computer to a screen:

  • The VGA (Video Graphics Array) cable has 15 pins, the port being a DB-15F, and the cable connector being a DB-15M, the VGA will be analog video rather than digital video,  it tells the screen what level of red, green, or blue we want per pixel.
  • The DVI (Digital Video Interface) is digital instead of analog, the difference being that analog transfers with a slopey wavelength to display the image, while the digital cables transfer in bits, a 1 or a 0 so the data is more absolute. The DVI connector will have 24 pins, and is seen on newer computers, it comes in two variants:
    • DVI-I: It has 24 pins and 4 additional pins for analog, this allows the computer to still transmit an analog signal if the monitor is not a digital one.
    • DVI-D: This one only allows for a digital  signal.

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