Video Summary 1
Topics covered in the videos 1.07, 1.09 and 1.11 * Ports * Connectors * Monitors * Video buses * Troubleshooting * Printers
Ports
* Serial ports transmit data 1 bit at a time. They are usually male and have 9-25 pins. * Parallel ports transmit data 8 bits at a time and are generally female with 25 pins. * Game ports have 15 pins laid out in two rows (female). * Video monitors have 15 pins but are laid in three rows (male)
Connectors
* Early mice used a serial connector and keyboards used a 5 pin DIN connector. * Modern mice and keyboards use a PS/2 technology which is a much smaller 6 pin DIN connector or a USB or wireless connection. * NIC- Network Interface card uses a RJ-45 connector. * The NIC is responsible for connecting a computer to local and distant networks or the internet. * It also converts parallel communication used by the motherboard system into serial communication used by the network cable.
Modem, Video and USB * It is the slowest possible way of connecting to the internet. * Its standard speed is 56Kbps although v.92 standard supports faster speed. * They are responsible for converting the analog signal from the phone line into a digital format a computer can use. * It also converts the digital signal back to analog when sending a transmission. They connect using a RJ-11 connector. * Modern computers come with two types of video ports , the VGA (analog interface) D-type, 15pins, 3 rows and the DVI (digital visual interface) * USB- Universal Serial Bus are hot swappable. USB1 transmit at 12Mbps and are 3meters in length. USB2 transmit at 480Mbps they are 5meters in length. * Around 125 – (127 maximum) devices can be plugged into the computer. * SCSI connectors come in different sizes. The type A 50 pin narrow SCSI and the type P 68 pin wide SCSI connectors. * IEEE 1394 is a serial connector known as Firewire. It is very fast and is used to stream media.
Monitors
* CRT (cathode ray Tube) use similar to TV screens. * LCD (liquid crystal display) use TFT (Thin Film Transistor) also referred to as Active Matrix.
Video Buses * They run in high speed video slot called AGP and PCI which is twice as fast as AGP. * When buying video cards buy a reputable brand and check bus type and speed. The faster the better and the more RAM on the card the better.
Troubleshooting
* Wavy image or screen flicker may be EMI (electromagnetic interference) could be caused by fluorescent lights and nearby audio speakers. * Never open a CRT monitor because they contain capacitors that store electricity.
Printers
* There are three basic types of printers , Dot Matrix and Laser * Dot matrix printers use a tractor feed system and a cluster of pins to strike an inked ribbon. They are used to print multi-part forms. They are slow and noisy and the paper jams. * There are two types of inkjet printers, thermal bubble printer which uses heat to force ink through a nozzle and a piezoelectric technology printer which uses electrical charge to force ink through a nozzle. It requires special paper with a wax coating and it uses a 4 color system CYMB (cyan, yellow, magenta and black). * Laser printers use an electro photographic process. It is expensive to replace toner cartridges. * There are six steps in laser printing, Cleaning, conditioning, writing, development, transferring and fusing. * Problems with laser printing could range from totally white page, totally black page, streaking, flakey or brittle print and garbled text. * Printers can be connected using 36 pin centronics, 25 pin parallel, USB, SCSI, 802.11, IrDA and blue tooth. * When connecting a printer run the cd first.
Terms
* Screen size is the measurement of the diagonal dimension of the screen * Contrast ratio is the ratio between the purest white the monitor can reduce and the purest black. The bigger the number the better. Example 1000:1 > 600:1 > 400:1. * Refresh rate –CRT is the time per second CRT beam writes to screen. The Higher the better. * Response time –LCD is the time needed to create new screen. The lower the number the better. * Interlacing –CRT is when the electronic beam writes to alternative lines and is used to compensate for slower refresh rates. * Dot pitch –CRT is the distance between phosphorescent dots that form images on the screen. * Pixel pitch –LCD monitor is number of addressable pixels on the screen. It is the same as resolution. * The queue is a list of print jobs waiting to be printed. * Spooling frees the operating system so you can do other things while your document printed.
Summary
I have learnt a great deal from the videos about different types of ports, connectors, printers and how to troubleshoot some of the problems they might have. I have learnt about NIC (network interface Card) which is responsible for connecting a computer to a local network. It also converts parallel communication used by the motherboard system bus into serial communication used by the network cable. I also learned that the more RAM and bus speed in a video card the better they will perform. There are also three types of printers the Dot Matrix, Inkjet and Laser. I might use this information when buying or when building my own computer choose the right printer and configure the spool so I can work on other things whist the computer is printing the document.