Foundations in Information TechnologyOctober 2, 2009, 2009UNIT ÃÂ 3:1. Describe the purpose of computer interrupts.
A.IRQ-An IRQ (Interrupt Request) interrupt controller assigns priorities to incoming IRQs and sends them to the CPU. It's kind of like taking a number at the local deli, except the hardware usually only has to wait a couple of nanoseconds instead of like twenty minutes. Since the interrupt controller can control only one device per IRQ line, if you assign the same IRQ address to multiple devices, you are likely to get an IRQ conflict. This can cause a range of errors from not allowing network connections to crashing your computer. So make sure you assign unique IRQs to new hardware you install and avoid the frustration and keyboard throwing that conflicts can cause.
B. PCI interrupts-1. Describe the function of a USB device and how to install a USB device on your computer.
2.Describe the three purposes of the power supply and why they are important.
A.Converting AC to DC.
B.Provide DC voltage to the motherboard, adapters and peripheral devices.
C.Provide cooling and facilitate air flow through the case.
3.Five (5) symptoms of power supply problems and possible solutions for each.
A.The computer constantly reboots.
(1.)Check to see if the computer is still under software warranty.
(2.)In Administrative Tools choose Performance Monitor and choose Monitoring Tools - Reliability Monitor. The list is a chart of software installs, uninstalls Windows updates and crashes. Check to see if your crashes started happening after you installed or uninstalled something.
B.The power supply is too hot to touch.
(1.) Check the cooling fans they may be clogged with dust causing it to overheat. If the heat gets to the point where your computer fails to start, unplug your computer for a few minutes and plugging it back in may fix it temporarily (if itÃÂs the power supply), but eventually it will have to be replaced.
C.The power supply fan does not turn when the computer is powered on.
(1.) If you notice hot air or a burning smell coming from the power supply, it is probably overheating. Other symptoms include spontaneous shutdown, rebooting or loss of power in components. If there is a problem with the power supply, you will probably need to replace it.
D.The power supply fan is noisy.
(1.) Sounds are indicating a fan that is working its way towards loose bearings. If that is the case, the fan should be replaced anyway, because it will fail soon.
(2.) Take a note of which way the fan rotation is, so you can replace it correctly. Unplug it and remove the four screws holding the fan in place and lift the fan out. Add a little sewing machine oil to the fan, so make sure you've got some handy. Do not use general purpose oil or lubricant (WD-40). The next job is to locate where to put the lubricant. You will usually see a sticker in the center of the fan. Carefully lift the sticker up, you might see either a hole with a spindle in it or a small rubber cap that you can pry off to reveal the hole and spindle. Put a drop of lubricant in the hole and spin the fan around a few times to work the lubricant in. Put the fan back (you did take a note of which way up the fan was before you removed it, didn't you?) Usually fans blow down onto the heat sink and CPU, so it is important you replace the fan the correct way up.
4.Explain the difference between UPS and SPS and give an example of a situation where you would recommend each.
A. UPS (Uninterruptible Power Supply) is a type of power supply that uses battery backup to maintain power during unexpected power outages. A typical consumer UPS is a surge protector that contains a high-capacity rechargeable battery. Smaller UPS devices look like bulky power strips, while larger ones may stand upright and look almost like small computers. While a UPS may only keep a computer running for 15 minutes after the power is lost, it is usually sufficient time to save all necessary documents and properly shut down the computer. That extra time can be invaluable to someone who is working on an important document or project that has not been recently saved. (Below is a picture of a UPS).
Here is an example situation; I live in Kansas, where a sudden freak tornado could hit. My desktop at the legal firm, where I am employed, does not have a battery in case of a sudden power lose. If I had a UPS, I would have ample time to save my documents or files without losing any important information for our clients.
B. SPS (Stand-by power supply) is a device powered directly from the main power, with the battery charging. The battery is the stand-by power supply. Should the power fail then the power supply is switched to the battery by an inverter. (Below is a picture of a SPS and the inverter).
6. Explain why documentation is important.
7. Search the internet and explain why an understanding of the binary numbering system is important to IT professionals.
8. Explain the process of converting binary numbers to decimal and decimal numbers to binary.
(1.) Binary to decimal conversion follows the same steps as decimal to binary, except in reverse order. Begin by multiplying 0 x 2 and adding 1. Continue to multiply the numbers in column by 2 and adding the digits from left to right in our binary number.
(Example 1): Convert 11101 from binary to decimal.
0 x 2 + 1 =11 x 2 + 1 =33 x 2 + 1 =77 x 2 + 0 =1414 x 2 + 1 =29Therefore, 11101 in binary is 29 in decimal.
(2.) Decimal to binary, dividing the number to be converted, say N, by 2 (since binary is in base 2) and making note of the remainder. Continue dividing the quotient N / 2 by 2, until reaching the division of 1 / 2, making note of all remainders.
(Example 1): Convert 21 into binary.
21 / 2 = 10 R=110 / 2 = 5 R=05 / 2 = 2 R=12 / 2 = 1 R=01 / 2 = 0 R=1Therefore, 21 in decimal is 10101 in binary.
References:Retrieved images from ÃÂUPS for LessÃÂ on October 6, 2009, from www.upsforless.comRetrieved images from ÃÂLaptop Battery DepotÃÂ on October 6, 2009, from www.LaptopBatteryDepot.comBrain, Marshall. "How Bits and Bytes Work." 01 April 2000. HowStuffWorks.com. Retrieved October 5, 2009, from Web site: http://computer.howstuffworks.com/bytes.htm