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Showing posts from September, 2020

Transport Layer Protocols

There are two fundamental protocols in the transport layer  1. TCP Transmission Control Protocol-- connection-oriented protocol 2. UDP User Datagram Protocol -- connectionless protocol Connection-oriented communication : establishes a logical (virtual) connection prior to sending data. Connectionless communication : sends data right away without establishing a logical connection Qn why do we have transport layer protocal?  IP provides a weak, but efficient service model (best-effort ) How should hosts send into the network?      i.)Flow Control      ii.) Too fast is bad; too slow is not efficient IP packets are addressed to a host           How to decide which application gets which packets?         NOTE TRASPORT LAYER IS RESPONSIBLE FOR PROCESS TO PROCESS DELIVERY PORTS port is a communication endpoints  Since there are many applications running on a computer, there is a need to decide which application gets which packet. A port number is a way to identify a specific application (proc
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How to Open an iPhone

1. Turn off the iPhone.  Press and hold the iPhone's Power button, then swipe the  slide to power off  switch at the top of the screen right. This will turn off your iPhone, thereby minimizing the chance of an electric shock. 2. Remove your iPhone's SIM card.   There is a small hole on the right side of your iPhone, a bit below the Power button; insert a thin object, such as a bent paperclip or a pin, into this hole to eject the SIM tray. Once the SIM tray pops out, simply remove the SIM card and push the tray back in. Make sure you store the SIM card in a dry, clean place. If you have a small plastic bag or container, it's best to store the SIM card there. 3 . Prepare a work surface.   You'll want a clean, well-lit, level surface on which to remove your iPhone's display. It will also help to have a soft item, such as a clean microfiber towel, on which you can rest your iPhone screen side-down. Consider giving the surface a good wipe-down with a damp rag and letting
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What is bios

1. Short for Basic Input/Output System, the BIOS (pronounced bye-oss) is a ROM chip found on motherboards that allows you to access and set up your computer system at the most basic level. The picture below is an example of what a BIOS chip may look like on a computer motherboard. The BIOS pictured is of an early AMIBIOS, a type of BIOS manufactured by AMI. What is included in a BIOS? The BIOS includes instructions on how to load basic computer hardware. It also includes a test referred to as a POST (Power-On Self-Test) that helps verify the computer meets requirements to boot up properly. If the computer does not pass the POST, you hear a combination of beeps indicating what is malfunctioning in the computer.
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PC Power Supply Repair

It’s 8:00 a.m., the neighbor’s dog barked all night, your coffee tastes like weak tea, and the phone message light blinks frantically. Full of resolve, you flip on your PC’s power switch, and ... presto —- nothing! No lights, no beep, no fan, nada. Suddenly you realize, it’s gonna be a really bad hair day. While there’s nothing I can do about the early hour or the coffee, I can probably help you get your PC back on its feet. The most common case of “Sudden PC Death Syndrome” is a defective power supply. The problem can come from many sources, like heat, power surges, and old age. While it’s easy enough to replace a power supply by swapping the old for new, it’s not always practical. A case in point: I have an AST 486SX that died when a truck plowed into the corner power pole and caused a two-hour black out. When the power came back on, my PC didn’t. A quick check showed the cause was a fried power supply. Unfortunately, a call to AST revealed, to my horror, that a replacement power s
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How USB Works

  Universal Serial Bus, or USB for short provides a single, standardized, easy to use way to connect devices to a computer. It uses a much higher data transfer rate than many common serial data formats. You can attach up to 127 individual devices to your computer using USB. USB can also supply enough power to smaller USB devices taking away the need to plug them into an external power source. This comes in handy for remote notebook useage. Some common examples of USB devices include: Printers Scanners Mice Keyboards Joysticks Digital cameras Webcams Speakers External hard drives If the device you are installing is new to the computer, Windows will auto detect it and asks for the driver disk if needed. If the device has already been installed, the computer will start using the device right away. USB devices can be connected and disconnected at any time making them hot swappable. Typical USB connectors have an A connector on one side and a B connector on the other. You can have other typ
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HOW TO FORMAT HARD DISK

  There may come a time when you will need to format your hard drive for some reason or another. These reasons may be because you are installing new operating system from scratch, or you want to wipe out a secondary drive to start fresh with new data or maybe even if you want to delete the partitions on a hard drive itself. Whatever the reason you are choosing to format your drive it’s very easy to do and there are several ways to do it. You can even format things like external hard drives and USB flash drives. Just keep in mind that with whatever drive you choose to format you will lose all the data on that drive so be sure to back it up first if you care about it! The first and easiest way to format a drive is to open Windows Explorer\File Explorer and find the drive you want to format. Then you can simply right click on it and choose Format from the list. You will then be presented with a dialog box showing you information about the drive and also giving you some settings that you c
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