17428Scheme-G

Sample Question PaperCourse Name :- Diploma in Computer Engineering Group Course Code :- CO /CD /CM / CW /IF Semester :- Fourth Subject Title :- Computer Hardware & Maintenance Marks :- 100 Time:- 3 hour Instructions: 1) All questions are compulsory 2) Illustrate your answers with neat sketches wherever necessary 3) Figures to the right indicate full marks 4) Assume suitable data if necessary 5) Preferably, write the answers in sequential order

Q.1) (A) Attempt any SIX: 12 Marks a. Write any four features of PCI bus. Ans. Feature of PCI

Extremely high-speed data transfer: 32-bit wide data transfer at the rate 33 MI-h gives a maximum throughput of 132 Mega bytes per second. Data transfer at the rate 66 MHz with 64 bit wide data is now being offered.Plug and play facility: This circumvents the need for an explicit address’ for a plug in board. A PCI board inserted in any PCI slot is automatically detected and the required 110 and memory resources are allotted by the system. Thus, there is no risk of clash of resources.New approach: It moves peripherals off the 1/0 bus and places them closer to the system processor bus, thereby providing faster data transfer between the processor and peripherals.Processor independence: The PCI local bus fulfills the need for a local bus standard that is not directly dependent on the speed and structure of the processor bus, and that is both reliable and expandable. It is for the first time in PC industry that a common bus, independent of microprocessor and manufacturer, has been adopted.Full multi-master capability :This allows any PCI master to communicate directly with other PC master/slave.Parity on both data and address lines: This allows implementation of robust system.Support for both 5V and 3.3 V operated logic.Forward and backward compatibility between 66 MHz and 33MHz PCI.

b. Write any two features each of FAT32, NTFS, File System. Ans.

Note : Student can write feature from this comparisionc. Write any four advantages of CRT display over LCD display. Advantage of CRT

1. Significantly lower cost compared to LCD, because the technology has matured.2. Color fidelity, so essential for graphic artists, has not been matched by LCDs.3. Contrast ratio allows perception of true black Darks are darker.4. Ability to adjust (multisync) images.5. Good for basic web surfing as well as uses requiring crisp, color-rich graphics and sharp

text.6. Work better at multiple resolutions.7. Displays full motion video better.8. Give you more pixels, translating to greater screen detail and ability to view more of a

document without scrolling.9. Screen images viewed from side angle are as good as when viewed straight-on (no

dilution of clarity or color.)10. Modem versions may include a sleep-mode for energy efficiency.11. Many now available with flat view screens for less glare, viewing convenience.12. Strong glass screen can with4and routine handling, and is hot easily damaged by

casual touch.Disadvantges of CRT

1. Radiation Emission are high.2. Larger size takes up more desk space the bigger the screen, the bigger the footprint.3. Heavy weight, 40 lbs and more4. Heavier size limits easy and convenient movement.5. Expends more energy and throws off heat.6. Measurement differs from usable screen area. Example a 19” CRT provides about 18”

of usable screen area.7. Less off-the-desk mounting options available.

Note : here only Advantages are needed

d. Define the terms TWAIN, and OCR with reference to scanner.

e. Give disadvantages of ink jet printer. (Any two points) Ans. AdvantagesInitial CostInk-Jet printers are one of the lowest cost products on the market. In the past, the quality of low inkjet printers have matched with its price. It means that when you buy an cheap inkjet printer, the quality of the images are not good. However, ink-jet technology has developed and improved so remarkably that the cheapest inkjet printers can create images with good quality.

QualityToday you can create images or documents with high quality by Inkjet printers. They used to use blurry effect to the texts or images before but with the powerful technology now, you are able to create more effects so that your images are more vivid and have the best quality.

SpaceCompare to laser printers, the ink jet printers have suitable size to put on the desk on your office or a small room in your home to serve to your work.

TimeDifferent from laser printer, the inkjet printer do not require time to heat the machine system before print. They have also shorter delay between the document being sent to print and the beginning of a print process.

DisadvantagesCartridge CostYou can buy a cheap inkjet printer first but with the replacement of the cartridges in a long time, the cartridge cost can exceed the machine cost.

SpeedYou can only use ink-jet printer to create little volumes of documents only because inkjet printer is slower than laser one.

InkThe replacement of cartridges causes some unexpected problems in the printing process. The most trouble we commonly face is when the printers are clogged with ink. There are cleaning cycles in inkjet printers to run but you must replace cartridges after used many times. Some companies offer service of refilling cartridges and you don’t need to buy new ones. The cost is down but it takes a lot of time to transfer cartridges.

MoistureAfter creating images or documents,we must wait until those dry. Sometimes it can delay our delivery process. There’s some risk if our documents smudge before drying.

Only Disadvantages to be considered – Another way of AnsweringAdvantages of inkjet printers:

1)     Low cost

2)     High quality of output, capable of printing fine and smooth details

3)     Capable of printing in vivid color, good for printing pictures

4)     Easy to use

5)     Reasonably fast

6)     Quieter than dot matrix printer

7)     No warm up time

 

Disadvantages of inkjet printers:

1)       Print head is less durable, prone to clogging and damage

2)       Expensive replacement ink cartridges

3)       Not good for high volume printing

4)       Printing speed is not as fast as laser printers

5)       Ink bleeding, ink carried sideways causing blurred effects on some papers

6)       Aqueous ink is sensitive to water, even a small drop of water can cause blurring

7)       Cannot use highlighter marker on inkjet printouts

Only Disadvantages to be considered

f. Define Line regulation and load regulation for a power supply.

g. Give any four features of SCSI-3.

h. List any four firewire features. Ans.The feature of firewire are listed as follows:a. Hot plug abilityb. Fire Wire can connect together up to 63 peripherals in an acyclic

topology.c. It allows peer-to-peer device communication, such as communication

between a scanner and a printer, to take place without using system memory or the CPU.

d. FireWire also supports multiple hosts per bus.e. It is designed to support Plug-and-play and hot swapping.f. Its uses six-wire cable is more flexible than most Parallel SCSI cables and

can supply up to 45 watts of power per port at up to 30 volts, allowing moderate-consumption devices to operate without a separate power supply.

g. FireWire 400 can transfer data between devices at 100, 200, or 400 Mbit/s data rates (the actual transfer rates are 98.304, 196.608, and 393.216 Mbit/s, i.e. 12.288, 24.576 and 49.152 MBytes per second respectively). These different transfer modes are commonly referred to as S100, S200, and S400.Cable length is limited to 4.5 meters (about 15 ft), although up to 16 cables can be daisy chained

using active repeaters, external hubs, or internal hubs often present in FireWire equipment.

h. Snap connection: No need for device ID, Jumper, DIP Switch, terminator etc.

i. Power Sourcing.j. Dynamic reconfiguration.k. Isochronous data transfers Firewire supports isochronous data transfers

which are suitable for digital video and other time critical media. The isochronous data transfer guarantees timely delivery of data between the nodes. The device, connected to the firewire bus, grabs an allocated portion of the bandwidth so as to guarantee the timely delivery of its data. Once the firewire bus bandwidth has been exhausted, it does not recognize the other connected devices.

DMA Support: The firewire, unlike USB and IDE, supports DMA transfers. Firewire is well suited for the following devices Digital camera, scanner, Hard disk drive, removable disk drives, printer tape back up, video tapes, video disks, set-up boxes, music systems.

Q.1) (B) Attempt any TWO 8 Marks a. Compare DDR2 and DDR3 (Any four points) Ans.

Number of PinsClock SpeedMax Transfer RateVoltage

DDR2 RAM240 pins400 to 1,066 MHz3,200 to 8,533 MB/s1.8V

DDR3 RAM240 pins800 to 2,133 MHz6,400 to 17,067 MB/s1.5V

From the DDR2 vs DDR3 table above, we can see that DDR3 RAM offers better performance while consuming less power.

The difference in clock speed and max transfer rate numbers look impressive on paper, but DDR3 RAM is in fact just 2 to 10% faster than DDR2 RAM for most real-world applications (depending on your hardware specification and usage).

DDR3 RAM consumes less power and produces less heat than DDR2 RAM at the same clock speed (e.g. DDR3 vs DDR2 RAM that is both running at 1,066 MHz). However there is a catch: RAM with higher clock speeds have higher power consumption so DDR3 RAM running at 2,133 MHz will still drain more power than DDR2 RAM at 1,066 MHz.

b. Describe the construction and working of plasma display. Ans. Plasma is referred to be the main element of a fluorescent light. It is actually a gas including ions and electrons. Under normal conditions, the gals has only uncharged particles. That is, the number of positive charged particles [protons] will be equal to the number of negative charged particles [electrons]. This gives the gas a balanced position.Suppose you apply a voltage onto the gas, the number of electrons increases and causes an unbalance. These free electrons hit the atoms, knocking loose other electrons. Thus, with the missing electron, the component gets a more positive charge and so becomes an ion.In plasma, photons of energy are released, if an electrical current is allowed to pass through it. Both the electrons and ions get attracted to each other causing inter collision. This collision causes the energy to be produced. 

Construction and WorkingTwo plates of glass are taken between which millions of tiny cells containing gases like xenon and neon are filled. Electrodes are also placed inside the glass plates in such a way that they are positioned in front and behind each cell. The rear glass plate has with it the address electrodes in such a position that they sit behind the cells. The front glass plate has with it the transparent display electrodes, which are surrounded on all sides by a magnesium oxide layer and also a dielectric material. They are kept in front of the cell.As told earlier when a voltage is applied, the electrodes get charged and cause the ionization of the gas resulting in plasma. This also includes the collision between the ions and electrons resulting in the emission of photon light.The state of ionization varies in accordance to colour plasma and monochrome plasma. For the latter a low voltage is applied between the electrodes. To obtain colour plasma, the back of each cell has to be coated with phosphor. When the photon light is emitted they are ultraviolet in nature. These UV rays react with phosphor to give a coloured light. Take a look at the diagram given below.

Working of Plasma display

The working of the pixels has been explained earlier. Each pixel has three composite coloured sub-pixels. When they are mixed proportionally, the correct colour is obtained.There are thousands of colours depending on the brightness and contrast of each. This brightness is controlled with the pulse-width modulation technique. With this technique, it controls the pulse of the current that flows through all the cells at a rate of thousands of times per seconds.

c. Compare the characteristics of CRT and LCD monitors (Any four) AnsThe two most common types of monitors that are being used today are CRT (Cathode Ray Tube) monitors and LCD (Liquid Crystal Display) monitors. CRT type monitors are the traditional monitors that we have been using for years. LCD type monitors are based on a newer technology and are becoming very popular, mainly because they have great space and energy saving advantages over CRT monitors. CRT and LCD monitors are based on completely different technologies, and thus have quite different display characteristics.

Physical SizeOne of the biggest advantages of LCD monitors is that they are compact and lightweight. An LCD monitor is based upon a very thin screen as opposed to the bulky tube of a CRT monitor. This means

that not only do they take up less of your desktop space, they can also be used in many places where a larger CRT monitor can not fit.

Display SizeNewer, larger LCD monitors are also appearing that have 15", 17", and even larger screen sizes that are comparable to the largest CRT monitors. LCD monitors are typically sized by their actual viewable diagonal measurement, but CRTs typically are not. For example, the viewable area on a 17" LCD monitor will typically measure 17" diagonally, but the viewable area on a CRT monitor will typically only measure 16" diagonally.

Colors Most CRT monitors are capable of displaying unlimited colors. Some LCD monitors are only capable of hundreds or thousands of colors, but many of the newer LCD's are capable of unlimited colors. Resolution CRT monitors are usually capable of displaying multiple video resolutions, each with the same quality. LCD monitors, however, usually has what is called a Native resolution, or the resolution that it displays best. The native resolution is generally the highest resolution that the LCD can display and this is the display resolution that will appear the crispest/sharpest.

Brightness Typically, brightness is not a concern with CRT monitors. LCD monitors are backlit and have

different levels of brightness. The brightness rating for an LCD monitor is commonly referred to as 'nits', and commonly range from 70 to 250 nits. The higher the nits, the brighter the display.

Viewing Angle A CRT screen can be looked at from a very wide angle, practically from the side, but an LCD monitor typically has a smaller viewing angle, needing to be viewed more directly from the front. From the side, the image on an LCD screen can seem to disappear, or invert colors.

Power Consumption and Radiation Emission Besides being compact and space saving, LCD displays offer several other benefits. For one,

LCD monitors consume much less energy than CRT monitors. This makes the LCD great for laptop and portable computers. Secondly, CRT monitors are known to emit harmful radiation, whereas LCD monitors do not.

Price CRT monitors are generally more affordable than LCD monitors. In the past LCD monitors have been very expensive but their costs have come down quite a bit in the last 1-2 years. A CRT monitor will cost less but will use more energy than a flat panel monitor. An LCD monitor will cost more but will conserve energy in the long run.

Q.2) Attempt any FOUR: 16 Marks a. State any four features of P67 chipset. Ans. The P67 Extreme6 is just one of several new Asrock motherboards built to accommodate Intel's LGA1155 processors and it happens to be their highest-end P67 motherboard.

The Asrock P67 Extreme6 feature list includes 64Mb AMI UEFI Legal BIOS with GUI support, six USB 3.0 ports, six SATA3 connectors, 8-channel audio, eSATA3, FireWire and dual-Gigabit LAN with Teaming.

Asrock boasts of the board's premium gold caps (2.5 x longer lifetime) along with 100% Japan-made high-quality conductive polymer capacitors. It also features the Digi Power Advanced V16 + 2 power phase design which is intended to improve the board's overclocking performance.

Asrock has added quite a lot to the standard P67 chipset features. Whereas all P67 motherboards have six SATA 3Gb/s ports (two can work at 6Gb/s speeds) Asrock has expanded the storage capabilities of their P67 Extreme6 by including not one but two Marvell 88SE9120 controllers.These controllers support a pair of 6Gb/s SATA ports each using a PCI Express 2.0 x1 (5.0Gb/s) lane. The Marvell controllers support NCQ (Native Command Queuing) but they don't have any kind of RAID support, unfortunately. Still the inclusion of these Marvell controllers means that the Asrock P67 Extreme6 features a grand total of ten SATA ports.Asrock has also expanded the networking capabilities of the P67 Extreme6 by including two Gigabit Ethernet controllers. The dual Realtek RTL8111E controllers each utilize a PCI Express 1.1 x1 (2.0Gb/s) lane and support a wide range of features such as Wake-On-LAN, LAN Cable Detection, Energy Efficient Ethernet 802.3az and Teaming.

Also requiring a PCI Express lanes are three Etron EJ168A controllers, each providing two USB 3.0 ports. Each controller uses a PCI Express 2.0 x1 (5.0Gb/s) lane and supports two USB 1.0/2.0/3.0 devices. Two of these controllers are used to provide four rear USB 3.0 ports while the third controller supports a pair of front mounted ports using an onboard header.

The list of embedded controllers doesn't stop there as Asrock also included the VIA VT6315N IEEE1394 FireWire controller supporting two IEEE 1394a ports with up to 400Mbps data transfer. This also uses a PCI Express 1.1 x1 (2.0Gb/s) lane providing one rear port and one front port using an onboard header.

Asrock has crammed in an enormous amount of PCI Express devices and that presents a problem as the P67 features just eight PCIe 2.0 (5.0Gb/s) lanes, which isn't enough. To solve the issue, Asrock uses a PLX PEX 8608 switch that provides up to eight more flexible ports, though we suspect that many of them have been used to connect the PLX switch to the P67 chip. This is not an ideal solution but it is the only one that allows Asrock to strap on so much extra hardware.

We found that the 8-channel audio is delivered by a rather traditional choice in the Realtek ALC892 codec which supports THX TruStudio Pro. Despite seeing this chipset on numerous Asrock boards before, we were unable to dig up any real info on it. The Realtek website only lists 8-channel codecs from the ALC861 to the ALC889.

(Note Diagram and Sketches are for Understanding Only Point are to be written)

b. Describe the following terms related to hard disk: MBR, sector, Cylinder, Track

Sectors, Clusters, Tracks, and Cylinders

A typical hard drive is an electromagnetic device made up of a number of disk-shaped pieces called platters that are stacked on top of each other (see the figure below). Each platter can store data on both sides and has a read/write

head that transfers data from the computer to the disk. To find information on these platters, drives are divided into a number of sections called Sectors, Clusters, Tracks, and Cylinders.

The following lists each type of section: Sector - A sector is the smallest unit of data that can be read or written from a disk.

Typically, sectors are 512 bytes in size, but other sizes including 1024 and 2048 are common.

Cluster - A cluster is the smallest unit of data that a file system can allocate for a file. Each cluster has a fixed size that is always a multiple of the sector size. Older file systems (FAT16) often allocated large cluster sizes of 32K or more, meaning that even small files of 1K would take up 32K of disk space. More modern file systems (FAT32 and NTFS) allow smaller cluster sizes. A file is stored optimally on disk as a series of contiguous clusters (clusters that are in order on disk). However, a file can be split into multiple clusters on different areas of the disk and this is called fragmentation.

Track - A track is a concentric ring of sectors on a platter. A read/write head can read all the data from a certain track by moving to a position and then rotating the platter.

Cylinder - A cylinder is a group of tracks in all the platters that are on top of each other.

Master Boot Record

Short for Master Boot Record, a small program that is executed when a computer boots up. Typically, the MBR resides on the first sector of the hard disk or diskette that identifies how and where an operating system is located so that it can be boot (loaded) into the computer's main storage or random access memory.. The program begins the boot process by looking up the partition table to determine which partition to use for booting. It then transfers program control to the boot sector of that partition, which continues the boot process. In DOS and Windows systems, you can create the MBR with the FDISK /MBR command

The Master Boot Record is also sometimes called the "partition sector" or the "master partition table" because it includes a table that locates each partition that the hard disk has been formatted into. In addition to this table, the MBR also includes a program that reads the boot sector record of the partition containing the operating system to be booted into RAM. In turn, that record contains a program that loads the rest of the operating system into RAM.

The master boot record (or MBR) is information that is normally stored in the first sector of the hard drive. This information is the data structure that identifies where an operating system (OS) files are located on the drive so that the OS can be loaded into the system’s memory (RAM) at the time of booting.

The MBR contains two elements; 1. executable code and 2. a partition table,

which identifies each partition residing on the hard drive. The MBR executable code or program begins the boot process by looking up the partition table to determine what partition holds the operating system.

This program looks for two hidden program files IO.SYS and MSDOS.SYS for DOS and executes IO.SYS program first. This program in turn loads MSDOS.SYS and COMMAND.COM into RAM to complete the process of booting.

From the above figure, you can see that a disk drive is composed of N sectors and each sector is of 512 bytes. Out of the N sectors, the first sector is assigned to the Master Boot record. The first 512 bytes of the BIOS is the Master Boot Record. MBR is composed of two components: a Bootsrapping program and the partition table. The code can be Windows loader, Unix loaders, or a virus.

Next, comes the partition table. The partition table is of 64 bytes and a 16 byte part which tells about the partition of the disk.The MBR is very small in size. Its machine code just helps to load that sector which is responsible for booting the associated partition.

c. Describe Write pre compensation with its use. Ans. Write PreCompensation

older hard disks used the same number of sectors per track. This meant that older disks had a varying bit density as you moved from the outside edge to the inner part of the platter. Many of these older disks required that an adjustment be made when writing the inside tracks, and a setting was placed in the BIOS to allow the user to specify at what track number this compensation was to begin.

This entire matter is no longer relevant to modern hard disks, but the BIOS setting remains for compatibility reasons. Write precompensation is not done with today's drives; even if it were, the function would be implemented within the integrated controller and would be transparent to the user.

Write precompensation (abbreviated WPcom in the literature) is a technical aspect of the design of hard disks, floppy disks and other digital magnetic recording devices. It is the modification of the analog write signal, shifting transitions somewhat in time, in such a way as to ensure that the signal that will later be read back will be as close as possible to the unmodified write signal. It is required because of the non-linear properties of magnetic recording surfaces.

A higher amount of precompensation is needed to write data in sectors that are closer to the center of the disk. In constant angular velocity (CAV) recording, in which the disk spins at a constant speed no matter where the data is written, the sectors closest to the spindle are packed tighter than the outer sectors and so require a slightly different timing to write the data in the most reliable way. CAV recording is used by most floppy disk systems and by older hard disk systems; the term CAV is not applicable to non-circular media, such as magnetic tapes. On magnetic tapes, precompensation is usually constant throughout the tape.

In the past one of the hard disk parameters stored in a PC's CMOS memory was the WPcom number, a marker of the track where stronger precompensation begins, i.e. the transitions are shifted further in time. This was needed by the old MFM and RLL hard disk controllers in common use until the early 1990s. These controllers were usually housed on

plug-in cards which could be plugged into the mainboard of the computer; in any case they were external to the actual drive and could deal with many different drives; thus they needed to be told some parameters about the particular drive type in use by the computer. One of these parameters was the WPcom number. This scheme allowed only two different precompensation strengths per disk, a lower one for the outer tracks and a higher one for the inner tracks, however this was enough for the simple low capacity drives of those days.

All hard disk types in common use after the early 1990s have a drive-specific controller built into the actual drive enclosure. This includes all IDE, SCSI, SATA, and SAS hard drive types, among others. Those internal controllers know everything they need to know about their specific drive, including which strengths of precompensation are needed on which parts of the disk.

Therefore they ignore any WPcom numbers stored in the computer's CMOS memory. Until the late 1990s, many PC BIOS setup programs still allowed the user to set WPcom numbers and other drive parameters for use with older hard disk types should the need arise; it wasn't always made very clear to the user that his more modern drive would almost certainly ignore the setting.Since then, the WPcom number is no longer even offered as a BIOS setting any more, as it is wholly obsolete now.Floppy disk controllers still need to deal with precompensation, but since there have never been more than five or six common floppy drive types in use on PCs, all of which need the same kind of precompensation, there was never a need for a BIOS setting concerning precompensation on floppy disk drives.

d. Describe use of jumper selections. (Any four) Ans.Jumper settings determine the order in which EIDE hard drives and other devices attached to a single interface cable are detected by a computer system. On SATA hard drives, jumper settings enable or disable enterprise-level features.Setting the jumpers correctly on a hard drive requires the proper placement of a plastic-encased, metal jumper shunt over two pins on the hard drive jumper block.Setting the Jumpers on a seagate hard driveCable Select. The drive is configured at the factory for a cable select setting. This allows the drive to assume the proper role of master or slave based on the connector used on the cable. For the cable select setting to work properly, the cables you are using must support the cable select feature. Current UltraATA cables with the 3 colored connectors do support this feature.

Master or single drive. If you are installing your Seagate hard drive as the only drive in the system or if it will be the primary boot drive for the system, the jumper should be set on pins 7 and 8.

Drive as slave. If you are installing the drive as an additional drive in your system, the drive should be set as slave by removing all jumpers. Remember to confirm that the original drive is set to a master position (If the limit capacity jumper is required for your installation it will need to remain in place).

Drive as master with a non-ATA-compatible slave (Seagate® drives only). Set a jumper on pins 5 and 6 and a jumper on pins 7 and 8. Use this jumper setting only if the drive does not work as a master.

e. Describe any six characteristics of CRT color monitor. Ans. Screen Size: The screen size is the measure of the diagonal length of the CRT. Since CRTs are measured diagonally from one corner of the case to the opposite instead of by their viewable area, a CRT will generally have a physically smaller display than that of an LCD with the same rated screen size. Screen size is one of the main variables that affects the price of a CRT monitor.

Refresh Rate: Refresh rate is the number of times per second the screen is redrawn expressed in hertz. Slow refresh rates will produce a noticable flicker. Higher refresh rates produce a picture with very little or no flicker that is easier on the eyes. A minimum of 75 Hertz is recommended.

Dot Pitch: Dot pitch is an important factor of the image quality of a monitor. Dot pitch is the measurement of the distance between two phosphor dots of the same color on a monitor. The smaller the dot pitch, the better image quality a monitor will have.

Resolution: Resolution is the number of pixels displayed on screen. The higher the resolution, the sharper and more detailed the picture will be. Resolution is expressed in the number of horizontal and vertical picture elements, or pixels. More resolution means quality of image is good.Resolution = Total number of Horizontal pixels X Total number of vertical pixels.

Frame RateHow many times a screenful of information is produced per second is called frame rate.

f. List any four advantages of optical mouse.

Ans.Cursor Accuracy The cursor accuracy of an optical mouse is typically high as it can analyze changing positions at 700 mm/sec and read up to 200 to 300 dots per inch. This means that it reads its location fast with high precision. In comparison to a mechanical mouse, an optical mouse does not wear down in accuracy because it does not have the same moving parts that a mechanical mouse has. However, the accuracy can be reduced if the open hole leading to the laser area is dirty.Convenience The optical mouse can be used on almost any surface as long as the laser can read the surface it is on. This means you could use the mouse on your leg, a notebook or almost any other object. Mechanical mice require a hard, flat and frictional surface for proper functioning. This makes the optimal mouse much more convenient to use on the go.

Energy One area that the optical mouse suffers is in energy use. Since friction and the movement of a tracking ball are used for a mechanical mouse, the energy required for its use is significantly lower than the optimal mouse. An optical mouse requires a steady stream of energy so that it can constantly relate the mouse's position to the cursor due to the constant images the mouse takes. This makes the mouse more accurate, but increases its accuracy. Most laptops come with a build in mouse pad or pointer mouse; however, these are less ergonomically designed than optical mice.Surface Issues The optical mouse uses the different surface images to adjust the cursor on your screen; however, surfaces that are shiny or are made of glass mirror and reflect the laser picture back to the picture reader software. This tricks the software into thinking that the mouse is not moving because its seeing its own reflection. You should avoid these types of surfaces when using an optical mouse.

Q.3) Attempt any FOUR: 16 Marks a. What is hyper threading technology? What is its requirement? Ans.Hyper Threading – Intel Proprietary

Intel’s HT Technology allows a single processor or processor core to handle two independent sets of instructions at the same time. In essence, HT Technology converts a single physical processor core into two virtual processors.The point of hyper threading is that many times when you are executing code in the processor, there are parts of the processor that is idle. By including an extra set of CPU registers, the processor can act like it has two cores and thus use all parts of the processor in parallel. When the 2 cores both need to use one component of the processor, then one core ends up waiting of course. This is why it can not replace dual-core and such processors.

Hyper-Threading is a technology used by some Intel microprocessor s that allows a single microprocessor to act like two separate processors to the operating system and the application program s that use it. It is a feature of Intel's IA-32 processor architecture.

With Hyper-Threading, a microprocessor's "core" processor can execute two (rather than one) concurrent streams (or thread s) of instructions sent by the operating system. Having two streams of execution units to work on allows more work to be done by the processor during each clock cycle . To the operating system, the Hyper-Threading microprocessor appears to be two separate processors. Because most of today's operating systems (such as Windows and Linux) are capable of dividing their work load among multiple processors (this is called symmetric multiprocessing or SMP ), the operating system simply acts as though the Hyper-Threading processor is a pool of two processors.

HT Technology was introduced on Xeon workstation-class processors with a 533 MHz system bus in March 2002. It found its way into standard desktop PC processors starting with the Pentium 4 3.06 GHz processor in November 2002. HT Technology predates multicore processors, so processors that have multiple physical cores, such as the Core 2 and Core i Series, may or may not support this technology depending on the specific processor version. A quad-core processor that supports HT Technology (like the Core i Series) would appear as an 8-core processor to the OS; Intel’s Core i7-3970X has six cores and supports up to 12 threads. Internally, an HT-enabled processor has two sets of general-purpose registers, control registers, and other architecture components for each core, but both logical processors share the same cache, execution units, and buses. During operations, each logical processor handles a single thread.

A processor with HT Technology enabled can fill otherwise-idle time with a second process for each core, improving multitasking and performance of multithreading single applications.

Although the sharing of some processor components means that the overall speed of an HT-enabled system isn’t as high as a processor with as many physical cores would be, speed increases of 25% or more are possible when multiple applications or multithreaded applications are being run.

To take advantage of HT Technology, you need the following:

Processor supporting HT Technology—This includes many (but not all) Core i Series, Pen-tium 4, Xeon, and Atom processors. Check the specific model processor specifications to be sure.

Compatible chipset—Some older chipsets may not support HT Technology. BIOS support to enable/disable HT Technology—Make sure you enable HT

Technology in the BIOS Setup.

HT Technology-enabled OS—Windows XP and later support HT Technology. Linux distributions based on kernel 2.4.18 and higher also support HT Technology. To see if HT Technology is functioning properly, you can check the Device Manager in Windows to see how many processors are recognized. When HT is supported and enabled, the Windows Device Manager shows twice as many processors as there are physical processor cores.

b. Write any four differences between CRT and LCD. Ans.CRTs and LCDs vary greatly and LCDs are replacing CRTs in today’s world. LCDs are lighter, slimmer and consume less power compared to CRTs. LCDs also give off less radiation compared to CRTs. However, CRTs have a sharper image quality compared to LCDs. LCDs can face with the problems of dead pixels, where a pixel dies and leaves small dot on the screen that does not change; whereas CRTs can face with burn-in problems. Other differences are listed below: 

  LCD CRT

Size (screen viewable size) Viewable size is reduced by 0.1” Viewable size is reduced by 0.99” to 1”

Thickness Minimum 1 inch; Pretty slim Bulky due to the heavy back

Weight Lighter Heavier

Image Quality Slightly less sharp images Sharper images

Energy Consumption Consumes less energy Consumes more energy

Refresh Rate Needs refresh rate (72hz minimum) No refresh rate (fixed at 72hz)

Screen Flatness 100% 90 degree flatness Only Mitsubishi and Sony’s aperture grille are 100% flat, rest are not

Radiation Small amount of radiation Has a significant amount of radiation

Glare Less glare More glare

Automatic Readjustment Auto resize button; readjusts the pixels The Auto-fit does not properly readjusts the image

Burn-In Doesn’t not face burn-in; but susceptible to image persistence

Burn-in can occur

Running Temperature Cooler than CRT The back gets warm

Dead / Stuck Pixel Can happen Doesn’t happen as images are “painted”

Price Expensive compared to CRT Cheaper

Resolution Native resolution works best, other resolutions may lose image quality

Can be used till max resolution without losing image quality; has multiple resolutions

Contrast 15000:1 Ratio changes according to types. Can range from 150:1 to 250:1

Life Span 60,000 hours Approximately 43,800; depends on usage

Colors 32 bit 8-bit max, 16.7 million colors.

Viewing Angle Depends on the technology Wide viewing angle

Blackness Blackness varies from dark gray to gray True black

Benefits Panels weigh less than plasma; use less energy; light; thinner; emits less electromagnetic radiation; no bleeding or smearing

Easy to move as cannot be wall mounted; good picture quality; cheaper; wide viewing quality; sharper image quality; multiple resolutions

Limitations Picture slightly less natural and "filmlike" than plasmas; slower refresh rate; limited viewing angle; blacks are brighter; susceptible to burn-out and image persistence; dead or stuck pixels may appear

Heavier, small screens; old technology (obsolete); susceptible to burn-ins

 

c. Explain the sequence of events in RS- 232 communications with signals. Ans.

d. Name two hardware tools and two software tools used for trouble shooting of PC. TOOLS in troubleshooting

Though POST is reasonably powerful, it cannot catch all the types of problems in hardware to verify if the hardware is totally fault free, we need more powerful and exhaustive test on the hardware modules and report detected faults with details. Many software are available by different manufacturer, out of which three are discussed here.

CHECKIT: -CHECKIT PRO is general-purpose diagnostic software by ‘Touchstone Software Corporation’. Its testing includes: -

- Test of system- Conventional, extended and expanded memory- Hard disk and floppy disk drive- Video card and display (including VESA card)- Keyboard, mouse

Several versions of CHECKIT product are available those are: -

a. CHECKIT PRO DELUXEb. CHECKIT PRO ANALYSTc. CHECKIT PLUS

CHECKIT PRO DELUXE gives detailed information about- Total memory installed- Hard disk type and size- Current memory allocation including upper memory usage- IRQ available and their usage- Modem/fax speed- Including a text-editing module that can be used to edit AUTOEXEC.BAT and CONFIG.SYS.

NORTONS DIAGNOSTICS : Norton utility is a software tool from SYMANTEC. It is very popular recovery package and it repairs most of disk problems. It is used by professional PC trouble-shooter and repair person for editing the disk at sector level. The person should know details about sector and tracks on disk. Norton utility includes DISK EDITOR, DISK DOCTOR, CALIBRATE, NDIAG, SPEED DISK, etc., utility programs.These software are used for hard drive diagnostic and software level repair. Together these utilities provide exhaustive testing of data and sector of hard disk drive.DISK DOCTOR works with both floppy and hard disk and test the capabilities of the drive to work with the system in which it is installed including the drive boot sector, file allocation table (FAT), file structure and data areas.Calibrate is used for intensive testing of data area of a drive, also test hard disk controller electronics. It is also used to perform testing of IDE, SCSI, interface drives and also perform non-destructive low level format.DISK EDITOR is used to directly edit the data from sector on disk.NDIAG provides information about the CPU, BIOS, coprocessor, video adapter, keyboard, mouse, hard and floppy drive types, memory installed, bus type (ISA, EISA, MCA) and serial and parallel port. It also provides ‘on-screen grid’, that can be used to test for various kinds of distortion is faulty monitor.

QAPLUS: -Software by DIAGSOFT is one of the most advanced and comprehensive sets of diagnostic for 386, 486 and Pentium based PCs. Its testing is extremely through and its is menu-based interface QAPLUS/FE also includes utility program for testing the speed of system. QAPLUS/FE is available on 51/4” and 31/2” disk regardless less of operating system whether is UNIX, DOS, OS2, etc.It can be used to start system, when problems are severe that system hardware cannot find.QAPLUS/FE can be used to test system’s: -1) Motherboard2) System RAM3) Video adapter4) Hard disk drive5) Floppy disk drive6) CD-ROM drive7) Mouse8) Keyboard9) Printer port10) Serial port

QAPLUS provides system configuration including hardware installed, its CPU, RAM installed, also it provides interrupt mapping.QAPLUS/FE provides information regarding TSR and device driver installed.

QAPLUS/FE has utilities to troubleshoot PC. These utilities include CMOS editor that can be used to change system, date, time, hard disk installed, etc.

- It consists of utility that will test hard disk and allow low level formatting on it.- It consists of floppy testing utility.- ‘CONFIG’ file and ‘BATCH’ file editor.

QAPLUS has a system burnt in capability meaning that it can be used to run system non-stop under full load of computation and hardware activity for the purpose of determining whether any system component likely to fail in real life use.

Hardware Tools :In IBM-PC there are various important tools and equipment that are available for successful troubleshooting. The various tools that should be available are: -

1. Screen driver set (flat blade)2. Phillips screen driver set with various attachments3. Nose pliers4. Flat pliers5. Tuners6. Cleaning brush7. Soldering iron8. De-soldering pump9. Solder metal 10. Cleaning cloth11. Hand held vacuum cleaner/blower12. Clips for connection13. Wire cutter14. Wire thruster.

The various equipment’s that are used are:1) Multi-meter :

This instrument is available in both analog and digital output form and can be used to directly measure values of voltage (V), current in Millie-amperes (MA) or amperes (A) and resistance in ohms () with a little finesse, this particular device can be used to check diodes, transistors, capacitors, motor-windings, relays and coils. The digital multi-meter contain facilities built right into the meter to test transistors and diodes. This is in addition to its standard function of current, voltage and resistance measurement.2) Digital logic probes :

The second basic piece of equipment needs to troubleshoot computers and peripherals are the digital logic probe. Basically, the logic probe is hand held device designed to test digital logic IC’s. To use it simply connect its power supply leads to the power supply of the circuit used for testing and touch its probe to the designated test point in the circuit. The light emitting diodes (LED) on the probe’s case indicate whether the test point is at logic high, a logic low, in a floating state, or whether the logic level at the test point is pulsating. The logic probe is often used in conjunction with a device known as a pulse generator probe or pulse. Physically, the pulse resembles the logic problem, but instead of detecting digital logic levels, the pulse creates them. Fig. 3.2 shows a logic pulse and the logic probe being used together to test the integrity circuit foil. The pulse injects a logic level at one end and the probe should detect the logic level at the other end of the foil. If no level, or pulse is detected, a problem such as cracked printed circuit board, exists which prevents signal from reaching its destination. This combination can also be used to check the continuity of peripheral cables and connectors.3) IC logic clips :

Another valuable tool for troubleshooting digital circuits is the IC logic clip. These devices are hinged to fit snugly over IC chips. IC logic clips exist in two forms: the simple logic clip, which extends the pins of the IC to provide convenient points to attach least leads. A simple IC logic clip is shown in figure. The

second type of IC logic clip is the IC clip-on test monitor shown in figure instead of simply providing convenient test points., the logic monitor uses LED’s to display logic levels in much the same manner as the digital logic probe. As a matter of fact, each IC lead acts as an independent test circuit. Logic clip monitors are available in 14 and 16 pin varieties and can be used to monitor TTL or MOS. IC’s . Clip-on test clip larger than 16 pins are not available.4) Oscilloscope :

It is one of the most versatile equipment. It is used to observe waveforms. The waveforms can be used to accurately measure pulse duration, frequency, voltage and phase shift, as oscilloscopes used for digital troubleshooting should be at least a dual-trace version with an effective band width (range of frequencies) of between 25 and 30MHZ. These are useful tools for breezing an analog or varying signal and displaying this static wave form on the face of a CRT screen cowered with a measurement grid. Not only can you measure voltage amplitudes and frequencies of test signals, you can also accurately resolve small time intervals and measure delay times, signal rise and fall times, and even located the intermittent glitch. Logic comparators :

The logic comparator is an instrument that allows the technician to validate the operation of a suspected bad IC by comparing its operation to that of a known good chip of the same type the logic comparator is excellent for detecting intermittent problems, such as missing pulses or noise induced glitches. However, a supply of good IC’s must be kept on hand as references.5) Logic analyzers :

The logic analyzers may be thought of as multi-channel oscilloscopes with memory capabilities. These devices can be set up to monitor the signals on all the bits of a data bus simultaneously. The analyzer is attached to the bus by a set of clip leads. The bits on the bus are loaded into the analyzer’s RAM memory according to a clocking signal, which may be generated internally or may originate from an external source. The analyzer has an other set of inputs called trigger inputs, which are used to breeze the data inputs and display them on a CRT tube. The trigger inputs may be used to breeze the waveforms around a particular event or when a particular word is present on the data bus. Some analyzers also include an RS 232 connector to allow the contents of the memory unit to be sent to a serial printer for display on paper. Other analyzers use small LED or LCD displays, which allow the memory to be, inspected one location at a time.6) Signature analyzers :This devices test computer circuits by sampling signals at selected test points while the computer is running specific software routines designed to exercise the various circuits. The signals obtained during the test are encoded and compared to a set of coded signals stored in the analyzers ROM memory unit when a test point’s code fails to match the stored code, the analyzer produces and error code which indicates that the defective area has been found. From there the location of the fault can be deduced from proper documentation, if it is available.

( List 4 tools of hardware and software and Eplain if needed two two tools)

e. Describe logic Analyzer and state its two advantages

f. Give the test sequence of POST.

Ans. n IBM PC compatible computers, the main duties of POST are handled by the BIOS, which may hand some of these duties to other

programs designed to initialize very specific peripheral devices, notably for video and SCSI initialization. These other duty-specific programs are

generally known collectively as option ROMs or individually as the video BIOS, SCSI BIOS, etc.

The principal duties of the main BIOS during POST are as follows:

verify CPU registers

verify the integrity of the BIOS code itself

verify some basic components like DMA, timer, interrupt controller

find, size, and verify system main memory

initialize BIOS

pass control to other specialized BIOSes (if and when required)

identify, organize, and select which devices are available for booting

The functions above are served by the POST in all BIOS versions back to the very first. In later BIOS versions, POST will also:

discover, initialize, and catalog all system buses and devices

provide a user interface for system's configuration

construct whatever system environment is required by the target operating system

(In early BIOSes, POST did not organize or select boot devices, it simply identified floppy or hard disks, which the system would try to boot in that

order, always.)

The BIOS begins its POST when the CPU is reset. The first memory location the CPU tries to execute is known as the reset vector. In the case of

a hard reboot, thenorthbridge will direct this code fetch (request) to the BIOS located on the system flash memory. For a warm boot, the BIOS will

be located in the proper place in RAMand the northbridge will direct the reset vector call to the RAM. (In earlier PC systems, before chipsets were

standard, the BIOS ROM would be located at an address range that included the reset vector, and BIOS ran directly out of ROM. This is why the

motherboard BIOS ROM is in segment F000 in the conventional memorymap.)

During the POST flow of a contemporary BIOS, one of the first things a BIOS should do is determine the reason it is executing. For a cold boot, for

example, it may need to execute all of its functionality. If, however, the system supports power saving or quick boot methods, the BIOS may be able

to circumvent the standard POST device discovery, and simply program the devices from a preloaded system device table.

The POST flow for the PC has developed from a very simple, straightforward process to one that is complex and convoluted. During POST, the

BIOS must integrate a plethora of competing, evolving, and even mutually exclusive standards and initiatives for the matrix of hardware and OSes

the PC is expected to support, although at most only simple memory tests and the setup screen are displayed.

(Above Answer is for Understanding)( Refer Techmax in that nice sequence is Given)

http://computer.howstuffworks.com/pc3.htmhttp://therealblacksheep.tripod.com/computer_post.htm

Q.4) Attempt any FOUR: 16 Marks a. With neat diagram explain the working of opto mechanical mouse.

Ans. Opto Mechanical mouseOnly difference is in the sensing circuit used to detect the movement of the mouse.

In a mechanical mouse a decoder is used to detect the distance mouse is moved on the tabletop, whereas in a opto-mechanical mouse a combination of LED (Light Emitting Diode) and Photo detectors is used to sense the distance traveled by the mouse.

Operation of Opto-Mechanical mouse :1. When the mouse is moved, the ball at

the bottom of the mouse moves and it turns two separate rollers fixed at 90 degree to each other.

2. One of these rollers is associated with back-and-forth movement of the mouse, i.e., vertical movement of the cursor on the screen.

3. The other roller is associated with the side-to-side movement of the mouse, i.e., the horizontal movement of the cursor on the screen.

Fig : Opto Mechanical Mouse

4. Each roller is further connected with a wheel. These wheels are rotated by the corresponding movement of the rollers.

5. There are small openings on the rim of each wheel. As the wheel rotates, a pair of LED and Photo detectors detect the number of openings passed between them.

6. Each opening on the wheel allow the light from the LED to fall on the Photo detector and generate an electrical signal.

7. The number of signals generated indicates the number of openings in the rim of wheel passed, i.e., the more is the number of signals, the farther has been the mouse moved.

8. These signals are passed to the PC through the wire connecting mouse to the main system.

9. The PC, in turn, passes them to the mouse driver software which then converts them into distance, direction and speed required for the movement of the screen cursor.

10.Depressing any of the mouse button also produces a signal. Depending upon the button being pressed, number of times the button being pressed and the present location of the cursor on the screen, the software accomplishes the task desired by the user.

Optical Mouse 1. In this type of mouse, instead of the customary ball and rollers, a light source and photo-

detector is used with a special mouse pad.2. When the optical mouse is moved on this special pad, light from the light source gets

reflected from the pad and special photo-detectors inside the mouse detect the horizontal and vertical movement based on the reflected light received.

3. One of these photo-detector is used to detect the back-and-forth movement of the mouse, i.e., vertical movement of the cursor on the screen and the other photo-detector is used to detect the side-to-side movement of the mouse, i.e., the horizontal (left to right and right to left) movement of the cursor on the screen.

4. The movement of the cursor on the screen depends on the number of the signals that is passed to the PC through the wire connected with the mouse.

5. The PC in turn, passes them to the mouse driver software which then converts them into distance, direction and speed required for the movement of the screen cursor.

6. Depressing any of the mouse button also produces a signal which is passed to the PC and the PC passes it to the software.

7. Depending upon the button being pressed, number of times the button being pressed and

the present location of the cursor on the screen, the software accomplish the task desired by the user.

( Refer for This Anser Opto Mechanical Only)

b. With neat diagram explain the working principle of flat bed scanner. Ans. Scanner:1) Scanner are used for getting existing graphical images, photos, signature, logos of

companies, paintings, drawing into the computer 2) Once these images are scanned & brought in the computer these can be included in the

documents or we can edit them using image editing software like paint brush, coral draw etc.

3) A scanner is useful for optical character recognition (OCR).4) Scanner is also usefull when interfaced with fax card so that document can be faxed after

scanning.5) Hand held scanner are cheapest and smaller in comparision with flat bed scanner.

Fig : optical Mouse

Flat Bed Scanner

1. A light source illuminates a piece of paper placed face down against a glass window above the scanning mechanism.

2. A motor moves the scan head beneath the page. As it moves, the scan head captures light reflected from individual areas of the page.

3. The light from the page is reflected through a system of mirror A lens focuses the beams of light onto light-sensitive diodes that translate the amount of light into electrical current.

4. The more light that’s reflected, the greater the voltage of the current. White spaces reflect more light than black or coloured letters or images.

5. An analogue to digital (A-D) converter converts each analog reading of voltage as digital pixel representing the scanned area.

6. A-D converter on a monochrome scanner stores only 1 bit per pixel, either o or off, representing black or white.

7. If the scanner is a colour scanner then the scan head makes three passes under the images and the light on each pass is directed through a red, green or blue filter before it strikes the original image.

8. The reflected signals from these three pass are converted into d information and stored to represent red, green and blue colour value of the scanned area on the page.

9. This digital information is sent to software in the PC, where the data is stored in a format with which a graphics program or OCR work.

c. Give the signal voltages for following colors of ATX connectors: Red, Black, Orange and Purple. Ans.

Additonal InformationThe only special pins are PWR_ON, +5VSB and pin 13 (+3.3V). The PWR_ON pin is controlled by the power supply and turned to +5V when the power supply is ready and that all power has stabilized and is ready for use. The +5VSB (+5 Volt Standby) always stays on even when the power supply is in standby. Pin 13 can either be a +3.3V power supply or can be used as a sensor by the power supply to measure losses in the cabling.

In addition to the voltages and currents that a computer needs to operate, power supplies also provide a signal called the Power Good signal, sometimes written asPower_OK or Power_Good and it is provided on pin 8 of the ATX main connector by a gray color wire. Its purpose is to tell the computer all is well with the power supply and that the computer can continue to operate normally. If the Power-Good signal is not present at startup, the CPU is held in reset state. If a Power-Good signal goes down during operation, the CPU will shut down. The Power-Good signal prevents the computer from attempting to operate on improper voltages and damaging itself.The ATX specification defines the Power-Good signal as a +5 volt (V) signal generated in the power supply when it has passed its internal self-tests and the outputs have stabilized. This normally takes between 0.1 and 0.5 seconds after the power supply is switched on. The signal is then sent to the motherboard, where it is received by the processor timer chip that controls the reset line to the processor.

Four wires have special functions:

PS_ON# or Power on is a signal from the motherboard to the power supply. When the line is connected to ground (by the motherboard), the power supply turns on. It is internally pulled up to +5 V inside the power supply.

PWR_OK or Power good is an output from the power supply that indicates that its output has stabilized and is ready for use. It remains low for a brief time (100–500 ms) after the PS_ON# signal is pulled low.

+5 VSB or +5 V standby supplies power even when the rest of the supply lines are off. This can be used to power the circuitry that controls the Power On signal.

+3.3 V sense should be connected to the +3.3 V on the motherboard or its power connector. This connection allows for remote sensing of the voltage drop in the power supply wiring.

Generally, supply voltages must be within ±5% of their nominal values at all times. The little-used negative supply voltages, however, have a ±10% tolerance. There is a specification for ripple in a 10 Hz–20 MHz bandwidth

d. State four advantages of UPS over normal power supply. Ans.

Uninterruptible power supplies (UPS) offer advantages that make them attractive investments for individuals and businesses alike. Although the most obvious advantage of an uninterruptible power supply is the maintenance of power to electronic equipment such as computers and routers in the event of a power outage, the UPS offers other important advantages.

Continuity of operation is the most basic feature a UPS offers. When plugged into an AC wall outlet, the UPS unit maintains a charge on its batteries during normal operation. Built-in electronics sense when external power is not present and switches the UPS output from wall power to AC power produced through its batteries and built-in inverter. By switching to battery power, UPS devices prevent momentary power glitches from resetting equipment and – in the event of a long term outage - give operators the chance to shut down equipment in an orderly and safe manner. The result of the proper operation of a UPS is higher productivity and less data loss.

Another important function of a UPS is surge protection. Because the circuitry in a UPS constantly monitors the incoming voltage, it can sense spikes and surges as well as outages. Therefore, when either of these dangerous conditions present themselves to the UPS, the UPS will switch to battery generated AC power, preventing the power surge or spike from reaching the devices connected to it. When the spike or surge is over, the UPS reconnects its output to the power coming from the wall.

An enhanced form of UPS, the line-interactive UPS, serves to clean its incoming power before sending it to its output. These units use components called autotransformers to adjust the voltage sent to the output, reducing the impact of unstable AC power sources that are chronically under or over voltage. By actively adjusting its output, the line-interactive UPS is able to make sure that computers and other connected gear are not subject to systemic power fluctuations that can cause failure.

Also significant among the advantages of an uninterruptible power supply is the so-called “online” UPS. Although this kind of UPS usually costs more than a basic standby unit, it offers the most benefit when sensitive equipment is in use. This kind of UPS always powers its internal battery source. Although it uses the incoming AC to keep the batteries charged, the AC output is always safe, taking the condition of the input AC power completely out of the equation. This guarantees that the power sent to attached devices is always free from noise and damaging wave forms as well as from outages, spikes, and surges.

----------------------Additional Information on Ups----------------------

WHY USE A UPS?Power problems can and do occur every day

Lightning strikes against power lines and electrical substations can cause substantial damage to electrical equipment, even to domestic and commercial users tens to hundreds of miles away. However, many spikes, surges and noise occurring every day

in homes and offices can have the same devastating effect on your computer hardware and software equipment as a lightning strike… An Overview of Electrical Disturbances:SPIKES:

A Spike is a dramatic increase in voltage normally lasting only a few milliseconds.Cause: Car accidents resulting in fallen power lines and lightning during an electrical storm.Result: Data corruption during a hard disk read/write cycle as well as component break down due to over-specified voltage and/or out-of-range voltage.BLACKOUT:

Total loss of mains powerCause: Power grid overload, lightning, car accidents and earthworks.Result: Loss of unsaved current work and possible loss of entire hard drive contents due to a head crash or disruption of the file allocation table.SURGE:

A short term increase in supply voltageCause: The switching off of large electrical loads e.g., commercial air conditioners, fridges and industrial motors.Result: Damage or premature failure of delicate electronic components due to excessive dissipation of heat.BROWNOUT:

A long-term decrease in supply voltage lasting up to several hoursCause: The switching on of large electrical loads e.g., commercial air conditioners, fridges and industrial motors. Other common causes are due to the over demand of utility power e.g., increased use of domestic air conditioners during summer months.Result: Possible head crash or disruption to the file allocation table due to the equipment’s power supply hovering between power-on and power-off states many times per second; also damage or premature failure of delicate electronic components due to excessive dissipation of heat.SAG:

A short-term decrease in supply voltageCause: As Brownout.  Result: As Brownout.NOISE:

EMI (Electronic Magnetic Interference) and RFI (Radio Frequency Interference) more commonly referred to as noise is induced into the power supply.Cause: Radiation from high energy equipment such as welders, radio transmitters, fluorescent lights and electric switching equipment. These devices superimpose a distorted signal onto the sine wave.Result: Keyboard lock-up and data corruption through unsynchronized radical impulses being saved as legitimate data.HOW DOES A UPS WORK?

A UPS is used in many ways. For the sake of this explanation we will use a computer as an example of a typical UPS application.A UPS works by regulating power to the electronic items you have connected to it (in the event of power surges or brownouts)In the event of a power failure a UPS will alert you to the fact there is no power and depending on the size of the UPS can either; Shut down your computer, Let your computer keep on running, Alert you to the fact there is a power failure which will allow you to shut down your equipment yourself.This means that anything you are working on can be saved and then shut your computer down and it also means that in the event of any form of power surge your computer is protected from damage.e. Sate four feature of USB. Ans. USB FeaturesThe Universal Serial Bus has the following features:The computer has the host adapter,• Up to 127 devices can connect to the host, either directly or by way of

USB hubs.• Individual USB cables can run as long as 5 meters; with hubs, devices

can be up to 30 meters (six cables cascaded) away from the host.• With USB 2., the bus has a maximum data rate of 480 megabits per

second.• A USB cable has two wires for power (+5 volts and ground) and a

twisted pair of wires to carry the data.• On the power wires, the computer can supply up to 500 milliamps of

power at 5 volts.• Low-power devices (such as mice) can draw their power directly from

the bus. High-power devices (such as printers) have their own power supplies and draw minimal power from the bus. Hubs can have their own power supplies to provide power to devices connected to the hub. 4

• USB devices are hot-swappable, meaning you can plug them into the bus and unplug them while the system is on.

• Many USB devices can be put to sleep by the host computer when the computer enters a power-saving mode.

The devices connected to a USB port rely on the USB cable to carry power and data.

f. Draw the diagram of centronics interface and explain function of any four signals. Ans.The Centronics interface provides a handshake protocol between a computer and a printer. The maximum data transfer speed depends on the clock rate of the computer system.Figure 1 show the signals of the Centronics interface. 

Fig: 1: signals of the Centronics Interface Signals from computer to printer There are 12 signals from the computer to the printer. Out of these, eight signals are data bits and four signals are control signals. The control signals are:  /STROBE /INIT /SCLTIN /AUTOFDXT All the control signal are “low-active”.  /STROBE   The printer should take the data when this signal is low /INIT  When /INIT is low, the printer resets its electronic logic and clears the

printer buffer /SLCTIN /SLCTIN is an interface enable signal. When this signal is low, the

printer responds signals from the controller /AUTOFDXT After printing a line, the printer will provide one line feed

automatically if this signal is low. This type of line feed is known as

hardware line feed Signals from printer to computer There are five status signals from the printer to the computer. Thease are: /ACK, BUSY, PAPER_END, SELECT and /ERROR  /ACK /ACK-signal is an acknowledgement for /STROBE signal from the computer.

When active, it indicates that printer has received data sent by the computer and is ready to accept next byte.

 BUSY  When BUSY is high, it indicates that the printer is busy and it cannot receive data. This signal becomes high under any of the following four conditions 1: On Receiving /STROBE active 2: During printing operation 3: When the printer is in offline state 4: When the printer sense some error condition 

 PAPER_END   When this signal is high, it indicates that there is no paper in the printer.

Either the paper is torn or the paper is over.SELECT  SELECT signal indicates that there is some error condition in the printer.

The three reasons for this signal are: 1: Mechanical fault or electronic fault in the printer 2: The printer is in offline state 3: There is no paper in the printer, i.e. paper-end state 

 

Q.5) Attempt any TWO: 16 Marks a. What is cache hit and cache miss? Describe L1, L2 and L3 cache. Ans.Cache is a small high-speed memory. Stores data from some frequently used addresses (ofmain memory).Cache hit Data found in cache. Results in data transfer at maximum speed.Cache miss Data not found in cache. Processor loads data from M and copies into cache. Thisresults in extra delay, called miss penalty.

Hit ratio = percentage of memory accesses satisfied by the cache.

Miss ratio = 1-hit ratio

(diagram is madatory)Types of Cache Memory

Level-1 Cache Level-2 Cache Level-3 Cache

Level-1Also called as L1 cache, primary cache, internal cache, or system

cache. When referring to computer processors, L1 cache is cache that is built into the processor and is the fastest and most expensive cache in the computer. The L1 cache stores the most critical files that need to be executed and is the first thing the processor looks when performing an instruction

Ll, or primary cache, is a small, high-speed cache incorporated right onto the processor’s chip. The Li cache typically ranges in size from 8KB to 64KB and uses the high-speed SRAM (static RAM) instead of the slower and cheaper DRAM (dynamic RAM) used for main memory. Using memory cache to hold memory values, or the most recently used data and instructions means the processor can retrieve the data from the cache instead of the system’s main memory, which is much slower than the cache memory.

Level 2 L2 is also

commonly referred to as secondary cache or external cache. Unlike Layer 1 cache, L2 cache was located on the motherboard o

n earlier computers, although with newer processors it is found on the processor chip. When L2 cache is found on the processor, if the cache is also on the motherboard, it is more properly known as L3 cache.Tip: The L2 cache is on the same processor chip and uses the same die as the CPU, however, it is still not part of the core of the CPU.L2 cache was first introduced with the Intel Pentium and Pentium Pro computers and has been included with ever process since, with the exception of the early versions of Celeron processor. This cache is not as fast as the L1 cache, but is only slightly slower since it is still located on the same processor chip, and is still faster than the computers memory. The L2 cache is the second thing the computer looks at when performing instructions.

L2,. or secondary cache, is memory between the RAM and the CPU (but not on the CPU chip itself and is bigger than the primary cache (typically 64KB to 2MB). L2 ATC (Advanced Transfer Cache) uses micro-architectural improvements, which provide a higher data bandwidth interface between the L2 cache and the processor core, and is completely scaleable with the processor core frequency. The L2 cache is also a unified, non-blocking cache, which improves performance over cache-on-motherboard solutions through a dedicated 64-bitcache

Level-3L3 Cache is Cache found on the motherboard instead of the processor on earlier computers. With today's computers this type of cache is a cache that is found on the same chip and die as the processors. In the below picture of the Intel Core i7-3960X Processor die, is an example of a processor chip containing six cores (CPUs) and the shared L3 Cache. As can be seen in the picture, the L3 cache is shared between all cores (CPUs) and is very large in comparison to what an L1 or L2 cache would be on the same chip because it is cheaper although slower.

Since more manufacturers are beginning to include L2 cache into their architectures, L3 cache is slowly replacing the L2 cache function the extra cache built into the motherboards between the CPU and the main memory (old L2 cache definition) is now being called the L3 cache.Some manufacturers have proprietary L3 cache designs already, but most desktop and notebook computers do not offer this feature yet. Micron has developed a chip set with 8MB of on-chip DRAM in the north bridge chip that acts as an L3 cache, but offering an L3 cache as standard equipment is still a future prospect.

b. State any eight motherboard selection criterion.

Ans. There are a wide variety of motherboards available today. When selecting a new mobo for your homebuilt computer, many things have to be taken into consideration, including:

Form Factor. The form factor is a set of standards that include the size and shape of the board, the arrangement of the mounting holes, the power interface, and the type and placement of ports and connectors. Generally, you should choose the case to fit the mobo, not vice-versa. But if there is a case that you simply mustuse (either because it's the one you happen to have or because you really, really like that case), then make sure the motherboard you choose is of a compatible form factor.

Processor support. You must select a mobo that supports the type and speed of processor you want to use and has the correct type of socket for that processor.

RAM support. Make sure that the motherboard you select supports enough RAM of the type (DDR-SDRAM, DDR2-SDRAM, RDRAM, etc.) that you want to use. Most motherboards manufactured as of this writing can support at least 4 Gig of RAM, with DDR2 being the most popular type because of its speed and relatively low cost. Most DDR motherboards also support dual channelDDR, which can further improve performance. But to take advantage of dual-channel, the RAM sticks must be installed in matched pairs, and the mobo must support it.

Chipset. The chipset pretty much runs the show on the motherboard, and some chipsets are better than others. The chipset cannot be replaced, so the only way to solve problems caused by a bad chipset is to replace the mobo. Read the reviews of other motherboards using the same chipset as the one you are considering to see if a lot of people have reported problems with it.

SATA support. There's really very little reason not to use SATA drives these days. They're priced comparably to EIDE drives, but deliver much higher data transfer. But to use SATA, your motherboard must have SATA support. (Well, you can actually install aftermarket SATA expansion cards, but why do that on a new computer?)

Expansion Slots and Ports. How many of each type of expansion slot are included? Will they be enough to meet your current and future needs? How about Firewire support? And does it have enough USB slots for all the peripherals you want to dangle off of it?

Reputation. Search the newsgroups to see if others have found the board you are considering to be a lemon. One excellent Web resource for motherboard research is Motherboards.org. When choosing a motherboard, reliability is the most important factor. Replacing a failed motherboard requires essentially disassembling the entire computer,

and may also require reinstalling the operating system and applications from scratch.

Compatibility. Most motherboards include drivers for all recent Windows versions, but check the documentation just to be sure. If you plan to use the board for a computer running another operating system (Linux, UNIX, BSD, etc.) first check the with the motherboard manufacturer to see if it is compatible, and then search the hardware newsgroups for the OS you will be using to see how that particular board has worked out for others.

On-Board Features. Do you want integrated audio or video? If you don't plan on using the computer for graphics, multimedia, or gaming, then you may be able to save money by buying a motherboard with less-than-spectacular integrated audio and/or video.

RAID Support. RAID (Redundant Array of Independent Disks) is a set of protocols for arranging multiple hard drives into "arrays" to provide fault tolerance and/or increase the speed of data access from the hard drives. Many motherboards have RAID controllers built-in, saving you the cost of installing an add-on RAID controller.

Cost. Even if you are on a budget, the motherboard is not the place to cut corners. Try a less fancy case, instead. A good motherboard is more important than neon lights. But at the same time, the fact that one mobo costs twice as much as another doesn't mean it is twice as good. By searching newsgroups and reading hardware reviews, you're likely to find some inexpensive boards that perform as well as (or even better than) boards costing a great deal more.

c. Explain the working of dot matrix printer with neat diagram. Ans.

A Dot Matrix Printer or Impact Matrix Printer refers to a type ofcomputer printer with a print head that runs back and forth on the page and prints

by impact, striking an ink-soaked cloth ribbon against the paper, much like a typewriter. Unlike a typewriter or daisy wheel printer, letters are drawn out of a dot matrix, and thus, varied fonts and arbitrary graphics can be produced. Because the printing involves mechanical pressure, these printers can create carbon copiesand carbonless copies. Each dot is produced by a tiny metal rod,also called a "wire" or "pin", which is driven forward by the power of a tiny electromagnet orsolenoid, either directly or through small levers (pawls). Facing the ribbon and the paper is a small guide plate pierced with holes to serve as guides for the pins. The moving portion of the printer is called the print head, and when running the printer as a generic text device it generally prints one line of text at a time. Most dot matrix printers have a single vertical line of dotmaking equipment on their print heads; others have a few interleaved rows in order to improve dot density. These machines can be highly durable, but eventually wear out. Ink invades the guide plate of the print head, causing grit toadhere to it; this grit slowly causes the channels in the guide plate to wear from circles into ovals or slots, providing less and less accurate guidance to the printing wires.

Dot-matrix printers are two important characteristics : Speed : Given in characters per second (cps), the speed can vary from about 50 to over 500 cps. Most dot-matrix printers offer differen speeds depending on the quality of print desired. Print Quality : Determined by the number of pins (the mechanisms that print the dots), it can vary from 9 to 24. The best dot-matrix printers (24 pins) can produce near letter-quality type, although you can still see a difference if you look closely.Advantages :1. can print on multi-part stationery or make carbon copies.2. Impact printers have one of the lowest printing costs per page.3. They are able to use continuous paper rather than requiring individual sheets.4. The ink ribbon also does not easily dry out.Disadvantages :1. Impact printers are usually noisy.2. They can only print low resolution graphics, with limited colour performance, limited quality and comparatively low speed.3. They are prone to bent pins (and therefore a destroyed printhead) caused by printing a character half-on and half-off the label.

Q.6) Attempt any TWO: 16 Marks a. With suitable block diagram, describe the construction of CDROM drive. Ans.

CDROM Working

The CD-ROM Drive performs the function of reading the data stored in Pits and Lands on the CD. The CD-ROM Drive consists of three fundamental components

A drive motor spins the disc.. This drive motor is precisely controlled to rotate between 200 and 500 rpm depending on which track is being read.

A laser and a lens system focus in on and read the bumps.A tracking mechanism moves the laser assembly so that the laser’s beam can

follow the spiral track. The tracking system has to be able to move the laser at micron resolutions.

OperationA CD-ROM drive operates by using a laser to reflect light off the bottom of the disc. The reflected light is then read by a photo detector. The overall operation of a CD-ROM drive is as follows;

1. The laser diode emits a low-energy infrared beam toward a reflecting mirror.

2. The servo motor, on command from the microprocessor, positions the beam onto the correct track on the CD-ROM by moving the reflecting mirror.

3. When the beam hits the disc, its refracted light is gathered and focused through the first lens: beneath the platter, bounced off the mirror, and sent toward the beam splitter.

4. The beam splitter directs the returning laser light toward another focusing lens. The last lens directs the light beam to a photo detector that converts the light into electric impulses.

5. These incoming impulses are decoded by the microprocessor and sent along to the host computer as data.

b. Describe frequency modulation (FM) and modified frequency modulation (MFM) method of recording with suitable example.

Ans. Recording Techniques The basic principle of writing data on the disk and reading data from the disk is same

as that of tape drive. In both the devices, there is a magnetic medium. Data is stored on the magnetic medium by causing magnetization of particles on the media. The magnetization is caused by passing current through a coil in the read/write head.

In both disk and tape, the head is stationary during the read/write operation. Only the media move. Presently, there are two standard formats for recording on a magnetic disk:

1. Frequency Modulation (FM) and 2. Modified Frequency Modulation (MFM).

FM Recording TechniqueThe FM format is known as single

density format whereas the MFM method is known as double density format.

In the FM format, a clock pulse is written at the beginning of each bit cell. The data pulse is written at the centre of the bit cell. If the data is 1, the data pulse is present. If the data is 0, there is no data pulse. Each bit cell is of 4 .ts duration for floppy disk. Figure shows FM recording format.

MFM Recording Technique

In the MFM format, the clock pulse is not present at the beginning of every bit cell. Fig. MFM recording Technique

When the data is 1, there is no clock pulse. Only the data pulse is present at the centre of the bit cell.

When the data is 0, following a 1 in the previous bit cell, neither clock pulse nor data pulse is written. But if the data is 0 both in the current bit cell and in the previous bit cell, then the clock pulse is written at the beginning of the current bit cell but no data pulse is written in the bit cell.

Figure shows the MFM recording format. In the FM recording, there are two flux changes per bit cell when l’s are recorded in all bit cells. In the MFM recording, since the clock pulses are eliminated, there is only one flux change per bit cell, when l’s are recorded in all

bit cells. Hence the duration of the bit cell in MFM is reduced to 2 s and the disk capacity is doubled in MFM.

Another technique which is more efficient than MFM (1.5 Times MFM to 3 Times FM) is the RLL (Run Length Limited) type of recording technique.

Run Length LimitedThe RLL encoding or the Run Length Limited encoding is the most common encoding

scheme used in the hard disk storage. This encoding scheme can be more accurately called as 2, 7 RLL encoding because in this scheme in a series or in a running in this length the minimum number of Os next to each other is two, and then maximum number of Os together can not be more than seven.

The RLL encoding scheme can store 50 percent more information than l encoding scheme on a given surface and it can store three times as much information as the FM encoding scheme.

The Run Length Limited name comes from the minimum number (Run Length and maximum number (Run Limit) of “no pulse” values allowed between pulses.

For the RLL encoding, an encoder/decoder (Endec) table is used to find the pulse signal to be used for different data bit groups.

The Endec table used by the IBM to convert bit information to the pulse signal.ExampleTo store 10001111 using different data encoding schemes, you need.(i) PP - PN - PN - PN - PP - PP - PP - PP, i.e. total 13 pulses FM scheme.(ii) NP - NN - PN - PN - NP - NP - NP- NP, i.e. total 7 pulses in MFM scheme. iii) NPNN NNNN PNNN PNNN°. 10 - 0011 - 11 , i.e. total 3 pulses in 2, 7 RLL scheme.

Fig. RLL Encoding Technique

c. With suitable block diagram describe the working of SMPS. Ans.

PC supplies provide +3.3V, +5V, and +12V at high amperage ratings as well as some low current negative voltages. Since most amateur equipment requires 13.8V +/- 15% some modification would be required. Also, high current for transmitting, up to 20+ amps for a 100W transceiver should be a requirement. Obviously, reliability and fail-safe modes for over-voltage, short circuit protection and cool quiet operation should considered. Recent design PC supplies fit those requirements very well.

Switch Mode Power Supply theory of operation

Most PC switch mode supplies have a circuit configuration similar to the one shown in the simplified block diagram below. 115V AC is rectified to DC, which is them applied to a power modulator. A PCM (pulse-width-modulated) signal converts the DC to a higher frequency (around 30KHz). The high frequency is stepped down for the low voltage DC, rectified and filtered to DC at 5V, 12V etc. The output of the 5V and possibly the 12V is sampled, compared to a reference and used to control the PWM generator to provide feedback to control the voltages. Various other controls for over-voltage, current limiting and temperature control are present, but not shown in the block diagram. It is the feedback voltage that will be used to increase to output to 13+volts for amateur use.

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