CompTIA A+

Peripheral Cables

*USB C

*Serial cables

Rs-232

Thunderbolt 1-2-3-4.

USB C: 

• Standardized format of USB connector.

• It describes the physical connector, it doesn't describe the signal. There could be many type of signal that can be put through the USB C side by side.

Serial cables (THE ONES IN OLDER COMPUTERS)

• D-subminiature or D-sub

• There were a lot of different formats, but the most common is the DB-9, DB-25.

• DB-9 is for the size, DB-25 is the number of pins it has.

• Technically the DB-9 is an E size connector (DE-9) but for pragmatism, the name DB-9 was kept to match the DB-25. Older models will say DE-9 and DB-9.

• These connections are called RS-232 (Recommended Standard 232). It was used in 1969, before USB, and standards for mouse and keyboards, also modems, printers, etc.

• Nowadays it's used to connect to an older switch or an older router, or a console port on those devices to configure them

• There used to be CONSOLEs that used RJ45 connectors to transmit serial, not ethernet. Moderns consoles have RJ45 and even moderner use USB.

The reason we need serial cables and we need to use the consoles, it's because it's the best ways to connect to the device when no other method is available. If there are problems connecting to a device through one of the existing interfaces, you can always connect to the console connection through a serial interface.

If that is done, mostly likely we'll be probably putting commands prompt  and typing commands at the keyboard to configure hat device. An adapter between USB to DB9 connectors or RJ45 are common.

Another method to connect to a connector is using a standard named Thunderbolt:

• It's a high speed serial connection that has data and power on the same cable. It makes it very easy to power a peripheral device with the same cable.

• Version 1 had two channels in a standard interface available in most devices, every channel allowed 10 gb per second per channel. 

• Version 2 increased to 20 gb/s for aggregated channels. The connector's name is Mini DisplayPort (MDP)

• Version 3 or Thunderbolt 3 included a newer standardized connector, the USB-C. With this one, now we can get 40 gb of aggregated throughput. It supports a maximum cable length of 3 meters if a copper cable is used. But it also supports optical connectivity up to 60 meters in length. It also allows Daisy-chain up to 6 devices (2 monitors, one external storage, etc.).

• Thunderbolt 4

• It still had 40 gb/s. It supports dual 4k displays and it increased bandwidth to the PCl Express Bus so that more data can be transmitted from the Motherboard to the peripheral devices.

Video Cables

• HDMI

• Display Port Interface

• DVI (Digital Visual Interface)

HDMI (High Definition Multimedia Interface)

• 20 Meter Maximum Range

• 19-pin connector, (refered as A connector).

Displayport Interface:

• Video format for Audio and video in the same conections.

• First display-type connections that send it in a packetized form like the Ethernet network. 

• It had compatibility wihth HDMI and DVI with adaptors.

• Sometimes it's the same connector as the Mini Display Port, but there is also a Full size DisplayPort, which has a locker of connector, like the RJ45. It generally has a button that allows you to connect it.

DVI (Digital Visual Interface)

• It's a single connector tupe with multiple type of connectors (D, I, Dual Link, etc.). It sends different amounts of traffic. A single link can send approximately 3.7 gb per second, HD (1920 x 1200 at 60HZ). It only sends DVI only sends video. 

• DVI-A: Sends analog signals, it coexists with VGA.

• DVI-D for digital signals

• I: Integrated, digital and analog in same conector.

VGA (Video Graphics Array)

• DB-15 for 15 pins, shaped like a D. Also known as DE-15.

• They have a standard blue color for standarized connectors for PC.

• It only sends Video. Image degrades after 5 or 10 meters.

• USB C sends video signals already.

Mobile High-Definition Link (MHL)

Storage Cables

• SATA

• eSATA

SATA (Serial AT Attachment):

• Standard interface in Desktops. There have been a number of versions:

• 1.0

• 1.5Gb/s

• 2.0= 3 3.0=6 3.2=16.

• External Sata is eSATA Matched the SATA version through a 2 meters cable. It's an external drive that can be connected.

SATA:

• Standards support two physical connections on the back. 15 Pins for power and 7 pins for data. 

• It connects the drive itself and the motherboard connector.

• One-to-one connector. (One cable for power, other cable for data).

• No Daisy Chaining.

• There are 8 SATA interfaces on a motherboard. It can suppor t8 total drives.

• THey are at the bottom of the motherboard.

• Generally they support SATA 2 and SATA 3. And they support different connections.

eSATA cable

• These are different, they use the same signal, but different connectors. The SATA is in the inside, the eSATA is outside of the computer.

• You can’t plug eSATA in a SATA conector in the motherboard. Their cables are different.

• eSATA connector are ports outside of the computer.

Adapters and converters

• DVI to HDMI

DVI to HDMI

• It’s very common, HDMI is backward compatible with DVI-D

• Their signal doesn’t need to be converted.

• The video quality doesn’t get lost

DVI-A to VGA

• They are vackward compatible with only 640 × 480 supported

• Since they are analog connections, a simple converter is needed.

• If the connection is digital, we will need a signal convertion.

USB to Ethernet

• RJ45 doesn’t tend to be in newer laptops.

• Wired connectivity is achievable through an RJ45 convertor to USB.

USB-C to USB-A

• Newer laptops don’t have USB-C, so adapters from USB-C to USB-A will allow us to plug an usb peripheral

USB Hub

• It’s a high speed USB connectivity that supports HDMI, SD cards, USB C, USB A, etc.

Copper connectors

RJ11 connector

• 6 position with 2 conductor (692C)

• They have 4 wires, wich would make it RJ14 but they are generally known as RJ11 connectors

• This one is used to plug a telephone or a DSL (digital subscriber line connection).

RJ45 (Registered Jack type 45)

• Larger connector, 8 position with 8 conductors (8P8C) AKA modular connection or ethernet connection.

• It’s different in size when comparing it to the RJ11

F-connector

• Used for tv connection and cable modem connection

• Coaxis comes from the provider, the F connector has a threaded connection at the end so that it can be screwed into the connection.

• DOCSIS (Dat Over Cable Service Interface Specification) It’s the satandard for the transmittion of data

Punchdown block

• They are very fast, you just push the wire in the conection and then push it with the tool. It’s very cheap.

USB 1,1/2.0 connectors

• Stadard A, B and Mini B and MIcto B

USB 3.0

• DIfferent connectors, except for the regular one.

• Molex connector

• 4 pin peripheral power connector used in older desktops.

• It provides +12 V and +5 V.

• AKA AMP Mate-n-Lok

• It powers up fans, drives and other components inside the desktop

• Generally they are paired with the power output of the things we need to power.

• They can also power the Motherboard in some Power Supplys

• Lightning

• 8-pin digital signals from Apple (iPhone, iPad, iPods)

• It had higher power output than Micro USB and it can be inserted either way.

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Fiber Connectors

ST-Straight Tip

• It’s a bayonet connector, you stick and twist it to lock i

  
  

  SC Connector (Subscriber Connector)

• AKA Square Connector or Standard Connector

• It is a push and pull connector, no bayonet in this one.

• It’s a popular connector used in many data centers

• It can be used with individual fibers or combine them into one units to connect and disconnect the send/receive side from a conecttion at once

LC Lucent Connector

• Smaller and more compact connector, it’s used with a clip on top

• AKA local connector or little conector

• Also has two sides together

• It’s smaller.

Memory

Random Access Memory (RAM)

• Most common type of memory.

• Temporary high speed storage used when executing applications and performing calculations in the computer.

• It’s the only way to work with data

• Drives put info in the RAM which is them stored in the SSD.

• Speed is associated with the overall performance of the computer, higher memory equals faster computer.

• Every motherboard is different in terms of what it expects from the system memory.

Memories upgrades need to be done with the documentation of the system to check for compatibility

DIMM

DIMM (Dual inline memory module)

• It’s dual because one side has electrical contacts and another one on the other sides but which are different. They are two separate lines of contacts.

• It’s the interface inside the motherboard

• The info written from memory is done in 64 blocks (data width of memory), this is used in calculations about how much information is written or read from memory.

• They have individual chips on the module, which makes it easy to install and removing it in the motherboard, you simply pull the lines that hold it and push them.

• They have individual memory chips these are Dynamic Random Access Memory, referred as RAM. They are random because any data on any chips can be accessed at any time instantenoously by referring to an address on the memory chip.

  
  

SO-DIMM

(Small Outline Dual in line Memory Module)

• Smaller version of the DIMM used in Laptops

• Process of instalment is similar, but these are horizontally to save room, it’s slided, pushed and it gets locked. DIMMs are vertical.

• SDRAM (Syncronous DRAM)

• Type of dynamic random access memory that is used in our computers.

• It’s synchronous because it’s synchronized to a common clock inside a computer. The clock keeps moving data at a very standard rate, since the CPU and memory run at a high speed, this allows the components to keep track of a standard rate of data that may be transferred back and forward.

• Memory transfer

• Older styles of memory use a SDR (Single Data Rate) to transfer info from memory into CPU and back. It uses the clock rate to manage the transfer. One single clock cycle processes one data, and so on.

• To improve the data transfer, the DDR (Double Data Rate) was introduced, which allows data to be transferred at the bottom and the top of the clock cycle, doubling the info that can be transferred.

• DDR3

• Version of DDR installed, it could be 3 or 2.

• It increased the capacity of the memory, but it’s not compatible with DDR2 (the 3 I mean).

• DDR4: Faster frequencies over DDR3, it’s newer and it’s not compatible with the older versions

• DDR5: Improved DDR4, more speed between the memory transfer, also not compatible with olver versions.

• If a new version would be invented, it’s likely it won’t be compatible.

• There’s an engenirreeing that prevents installment of wrong modules in motherboards. The Key, (curve) is different in everyone, that makes it incompatible when you want to install them.

Memory Technologies

Memory systems are different

Memories that are used on PCs are different than the ones on servers.

Parity Memory

• It includes an extra parity bit with each byte stored in a memory.

• It might not always detect errors detected and it might not be able to correct them, but it does notify an error. It generally needs a reboot, but we know at least where it happened, and if we know where that error is, we can fix it

ECC

• (Error Correction Code)

• We can provide the correction, it detects them and corrects them, at least it can. The system continues to run normally

• They are the same size and look very similar, we have to look at the details to tell the differences

Errors

• The memories can recognize that an error has occurred because it’s saving extra information in the memory called a Parity Bit, it can look an entire bite (8 bits), and it adds a 9-bit to that byte. In most system this is referred as an Even Parity, because the added bit makes an even number. If it’s already an even number, the parity bit is added as a 0, if not, it adds a 1.

• When writting the info in memory, we write it with the 8 bits and the Parity bit. When we retrieve the info from memory, we evaluate the byte with our own parity checks, we compare the parity bit with the one stored in memory. If they are identical, we can assume the bite is clear, if not, we can assume there was an error with the process of writting that info to memory or reading that info from the memory module.

• Basically, if the count is an uneven number, along with the parity bit, there was an error.

CPU to Ram throughput

• There’s an enormous amount of data between the PC and the memory, this is called the Memory Bandwith and it can determine how quick is a computer.

• This is meassured in MT/s (Megatransfers/s, Million transfers per second)

• Examples: 32 GB DDR5, 1X32 GB 5600MT/S

Multi-channel memory

• One of challenges of increasing speed is that there is a limit, in the transfer between memory cpu, memory, there might be a max out of total amount of throughput over that pathway.

• The CPU has a vital time while it waits for the transfer, while that happens we could perform other calculations, but if the bandwith is not enough to support the speed of the CPU, an additional challenge might be put so that the CPU can communicate to multiple memories simultaneously to increase the throughput.

• PCs could support multi channel memories to accomplish this

• There are dual, triple and quad channel memories, this represent the amount of memory modules that can be put.

• Memory combinations should match each other (all of them have to be the same type and ideal same make and model).

• Memory modules are usually colored in the motherboard

• Even though there can be motherboards with just one slot for one 32 GB memory module, having two of 16 gb provides additional throughput between the CPU and the memory.

Storage Devices

When we power of out computers,all of the information in memory disappears

To retrieve the info, we need a device that can maintain the data, even when the system has no power.

This is done through:

• Hard drives

• Solid state drives

• Flash drives

• Memory cards

• Optical drives

• Hard Drive

• Magnetic device with rapidly spinning platers, it stores the data in the platters

• It’s a random method of storage, the info is stored anywhere and it can be accessed immediately accessing the address of the info

• The platters spin around thousands of times in a minute

• It has a moving arm that takes a small hit and it reads and writes info in the platter, and mechanical aspects that move the arm

• Due to the mechanical aspect of them, they can fail

• We can’t remove the cover because the drives must keep dust-free.

• It was a spindle in the middle that spins the drive in different speeds

• Acutator that moves the arm, and the head the performs the read/write in the platter.

• Different hard drives speed at different rates, we can see that in the specifications of the drive (15000 per minute, 10000 7200 5400, etc)

• The diference in revs is that the arm is in one place, so we have to wait for the platter that moves so that the arm can move underneath the head. The faster the speed, the lower the latency (faster with faster revolutions).

• Often there are more than