COMPUTER HARDWARE - SHORT NOTES

Short Notes on Computer Hardware & Troubleshooting

1. Computer Hardware & Troubleshooting
UNIT-1
1. State some parts of PC?
A typical PC contains the following hardware:
 Case
 Power Supply
 Motherboard
 CPU
 Memory
 Hard Disk
 Floppy Disk
 CD-ROM
 Video Adapter
 Sound Card
 Modem
 Mouse
 Keyboard
2. What is mean by RAM?
The memory chips store information, temporarily, for short term use. A PC's memory
only contains information when the PC is on. When the PC is turned off, the information
in the memory chips disappears.
3. Define ROM?
Its is expanded as Read-Only Memory. ROM is a permanent memory. It is non-volatile.
4. Differentiate RAM and ROM?

RAM ROM
It is RANDOM ACCESS MEMORY.
The memory chips store information,
temporarily, for short term use. A PC's
memory only contains information when
the PC is on. When the PC is turned off,
the information in the memory chips
disappears.
It is READ_ONLY MEMORY.
ROM is a permanent memory. It is non-
volatile.


5. What is mean by SMPS?
A switched-mode power supply, switch-mode power supply, or SMPS, is an
electronic power supply unit (PSU) that incorporates a switching regulator — an internal
control circuit that switches power transistors (such as MOSFETs) rapidly on and off in

2. order to stabilize the output voltage or current. Switching regulators are used as
replacements for the linear regulators when higher efficiency, smaller size or lighter
weights are required.

6. Define interrupt?
In computing, an interrupt is an asynchronous signal from hardware indicating the need
for attention or a synchronous event in software indicating the need for a change in
execution.
7. Illustrate pnp?
PNP is plug and play. Devices are joystick etc. pnp devices are configured and each and
every pnp devices is displayed in screen by BIOS.
8. Define BIOS?
BIOS, in computing, stands for Basic Input/Output System also incorrectly known as
Basic Integrated Operating System. BIO refers to the software code run by a computer
when first powered on. The primary function of the BIOS is to prepare the machine so
other software programs stored on various media (such as hard drives, floppies, and CDs)
can load, execute, and assume control of the computer. This process is known as booting
up.
9. State the step involved in booting the computer?
1. computer BIOS runs self-tests
2. if no problems, BIOS tries to boot an operating system from a drive. Older computers
usually try a: drive first, c: drive second. Newer computers have a BIOS setting to tell
BIOS where to look first, usually c:
3. BIOS looks for bootup files (usually on drive c:
4. most common bootup files are the Microsoft bootup files: io.sys, msdos.sys, and
command.com
5. next, DOS looks for config.sys file and loads drivers line by line.
6. next, DOS looks for autoexec.bat file and executes DOS commands or runs given
programs line by line.
10. For what one long and one short beep is used ?
One long beap and one short beap is used for System board errors .
11. For what three long beep used?
Keyboard errors.
12. What is meant by copy right?

3. Copyright is a set of exclusive rights granted to the author or creator of an original work,
including the right to copy, distribute and adapt the work. Copyright does not protect
ideas, only their expression or fixation. These rights can be licensed, transferred and/or
assigned.
13. What is mean post sequence?
The POST detect any problem it gives some beep blow or some error messages will be
display. A boot process will be stopped. If the POST finds no problem the boot process
continues the sytem BIOS.
14. Differentiate maskable and non maskable interrupt?
Maskable interrupt Non-maskable interrupt
A program wants to selectively disable
certain interrupt is known as masking
interrupt.

There are some interrupt which are lik
emergency operations, the servicing of the
particular operation should not be delayed.
15. What is mean by system check?
The BIOS begins the series of test on the system including the amount of memory
detected on the system. It displays error message for any problem detected instead of the
beep sound.
16. Differentiate SRAM and DRAM?
SRAM DRAM
It is static ram.
its contents of all the location will be present
as long as power supply is present.
 it is dynamic ram.
it can retain contents of memory location
only for few ms.
17. State the different types of memory?
Sequential access memory.
random access memory.
static RAM.
dynamic RAM.
18. Define sequential access memory with example?
Read or write access in sequential. Time taken for first location is short and last location
is long.

4. 19. What is meant by MAR,MDR?
MAR-memory address register.
The register holds the memory address.
MDR-memory data register.
The register holds the data in memory.
20. What is meant by memory access time?
The time taken by memory to supply the contents of the location from the time it receives
the RD signal operations called MAT(memory access time).
21. What is meant by memory cycle time?
The memory access time and additional recovery time combined as known as Memory
cycle time.
22. State the concept of hand shaking?
The replying after a request is received by a device to another device is known as
acknowledgement. The process is known as handshaking.
23. Give the system configuration of own system?
RAM-2B, MOTHERBOARD-INTEL PR 31, PROCESSOR-DUAL CORE
NVIDIA GRAPHICS CARD 128MB & 500GB HARDDISC.
24. State two advanced processor?
i) Intel 5i ; ii) Intel 7i
25. What is mean by mass storage? State some mass storage device?
A Mass Storage refers to devices for storing large amounts of data. These devices can be,
Portable Hard Disks, Flash Drives & Memory Cards.
26. What is mean by memory organization?
Memory organization consists of memory address register(MAR) which is used to store
the address in register specified and memory data register(MDR) which is used to store
the data in register. The entire activity is controlled by memory contol logic. Read and
write operations are done.
27. Define IO interface?
I/O Interface is required whenever the I/O device is driven by the processor. The
interface must have necessary logic to interpret the device address generated by the
processor.

5. 28. Define CMOS?
Complementary metal–oxide–semiconductor (CMOS) is a technology for constructing
integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static
RAM, and other digital logic circuits.
29. State the types of interrupt?
maskable interrupt, non-maskable interrupt (NMI), inter-processor interrupt (IPI),
software interrupt, and spurious interrupt.
30. What is the functions of BIOS?
BIOS, in computing, stands for Basic Input/Output System also incorrectly known as
Basic Integrated Operating System. BIO refers to the software code run by a computer
when first powered on. The primary function of the BIOS is to prepare the machine so
other software programs stored on various media (such as hard drives, floppies, and CDs)
can load, execute, and assume control of the computer. This process is known as booting
up.
UNIT-2
1.WHAT IS ISA?
The full form of ISA is INDUSTRY STANDARD ARCHITECTURE . ISA originated as an
8-bit system in the IBM PC in 1981 as the XT bus architecture. The newer 16-bit standard was
introduced in 1984. It was designed to connect peripheral cards to the motherboard.
2.WHAT IS PCI?
THE FULL FORM OF PCI IS PERIPHERAL COMPONENT INTERCONNECT . It
specifies a computer bus for attaching peripheral devices to a computer motherboard. The PCI
bus is common in modern PCs, where it has displaced ISA and VESA Local Bus as the standard
expansion bus, but it also appears in many other computer types.There are three versions of PCI
they are,
PCI 1.0,PCI 2.0,PCI 2.1
3.COMPARISON OF ISA AND PCI?
ISA PCI
Introduced in the year 1981 by IBM Introduced in the year 1990 by INTEL
PENTIUM.

6. The two versions of ISA are EISA and
VESA
The two versions of PCI are PCI 1.0,
PCI 2.0,PCI 2.1
4.WHAT IS EISA?
The full form of EISA IS EXTENDED INDUSTRY STANDARD ARCHITECTURE. BUS
MASTERING is a concept of EISA. EISA is extended upto 32-bits.
5.WHAT IS VESA?
The full form of VESA IS VIDEO ELECTRONIC STANDARD ASSOCIATION . This also
consist of 32-bits.
6.WHAT IS BUS MASTERING?
BUS MASTERING MEANS ‘DIRECT TRANSFER OF DATA’.
It is a concept of EISA.
7.WHAT IS SCSI?
The full form of SCSI is SMALL COMPUTER SYSTEM INTERFACE .It was produced by
SUZZY by SASI.It is used to transfer data from one device to another. SCSI is most commonly
used for hard disks and tape storage devices, but also connects a wide range of other devices,
including scanners, printers, CD-ROM drives, CD recorders, and DVD drives.
8.WHAT ARE THE STANDARDS OF SCSI?
The standards of SCSI are:
SCSI 1
SCSI 2
SCSI 3
ULTRA 2
ULTRA 3
ULTRA 320
ULTRA 640
9.WHAT IS THE HEIGHT AND DEPTH OF PCI SLOTS?
HEIGHT:107 MM[4.2 INCHES]
DEPTH:312 MM[12.283 INCHES]
10.WHICH IS CALLED AS FAST SCSI?
SCSI 2 is called as FAST SCSI. Because it has doubled the maximum transfer rate to 10 MB/s
11.WHAT IS LVD AND HVD?

7. LVD- LOW VOLTAGE DIFFERENTIATOR
HVD- HIGH VOLTAGE DIFFRENTIATOR
The LVD CABLE length is 12 metres.
The HVD CABLE length is 25 metres.
12.WHY CRC IS USED IN ULTRA 3?
The full form of CRC IS CYCLIC REDUNDANCY CHECK .It is used to correct error
automatically.
13.DIFFERENCE BETWEEN ULTRA 320 AND ULTRA 640?
ULTAR 320 ULTRA 640
The data transfer rate is 320 Mb\s The data transfer rate is 640 Mb\s
It was introduced in the year 2002 It was introduced in the year 2003.
14.WHAT IS IDE?
The full form of IDE IS INTEGRATED DRIVE ELECTRONICS .It is a group of ATA.It is
used to connect floppy,cd-drive and hard disk.
15.WHAT ARE THE DATA TRANSFER RATE FOR SCSI 1,SCSI 2 AND SCSI 3?
SCSI 1- 3Mb/s,5Mb/s upto 10Mb/s
SCSI 2- 10Mb/s to 20Mb/s
SCSI 3- 40Mb/s
16.HOW MANY PINS ARE PRESENT IN IDE?
40 pins are present, in addition 4 pins are optional.Totally 44 pins are present.
17.WHAT IS ATA?
The full form of ATA IS ADVANCE TECHNOLOGY ATTACHMENT ..
18.State different types of cable?
A cable is two or more wires running side by side and bonded, twisted or braided together to
form a single assembly.
The cable types are:
 Coaxial
 Twisted pair
 Fiber optic
19.State different types of connectors?

8. There are three different types of connectors .They are
 Front panel
 On board
 Back panel
20.What are the different types of co-axial cabels?
There are two different types of co-axial.They are
 Thin co-axial
 Thick co-axial
21. Define fiber optic cable?
An optical fiber cable is a cable containing one or more optical fibers. The optical fiber
elements are typically individually coated with plastic layers and contained in a protective tube
suitable for the environment where the cable will be deployed.
22. EXPLAIN TWISTED PAIR CABLE:
A type of cable that consists of two independently insulated wires twisted around one another.
The use of two wires twisted together helps to reduce crosstalk and electromagnetic induction.
While twisted-pair cable is used by older telephone networks and is the least expensive type of
local-area network (LAN) cable, most networks contain some twisted-pair cabling at some point
along the network. Other types of cables used for LANs include coaxial cables and fiber optic
cables.
23. WHAT ARE THE TYPES OF TWISTED PAIR CABLE ?
Twisted pair cable is available in two primary varieties: Shielded Twisted Pair (STP) and
Unshielded Twisted Pair (UTP). The difference between the two varieties is the degree of
shielding against outside interference that is provided by the covering over the wires. Unshielded
does not contain any special shielding, whereas Shielded does.
24. HOW MANY WIRES ARE USED IN TWISTED PAIR CABLE?
Both UTP and STP come in stranded and solid wire varieties. The stranded wire is the most
common and is also very flexible for bending around corners. Solid wire cable has less
attenuation and can span longer distances, but is less flexible than stranded wire and cannot be
repeatedly bent.
25. DIFFERENCRE BETWEEN 5PIN AND 6 PIN DIN CONNECTOR:
5PIN:

9. The first two generations of PC keyboards (PC and AT keyboards) used a 5-pin DIN connector.
6PIN:
The 6-pin Mini-DIN also replaced the serial port for mice.
26. WHAT IS MEAN BY SERIAL CONNECTOR?
In computing, a serial port is a serial communication physical interface through which
information transfers in or out one bit at a time (contrast parallel port).[1] Throughout most
of the history of personal computers, data transfer through serial ports connected the computer to
devices such as terminals and various peripherals.
27. What is mean by parallel connector?
A parallel port is a type of interface found on computers (personal and otherwise) for connecting
various peripherals. In computing, a parallel port is a parallel communication physical interface.
It is also known as a printer port or Centronics port. The IEEE 1284 standard defines the bi-
directional version of the port, which allows the transmission and reception of data bits at the
same time.A DB-25 parallel printer port, as on IBM-PC style, and a few other types of
computers.Micro ribbon 36 pin female, such as on printers and on some (particularly industrial
and early- and pre-1980s personal) computers.
28. Define MODEM
A modem (modulator-demodulator) is a device that modulates an analog carrier signal to encode
digital information, and also demodulates such a carrier signal to decode the transmitted
information. The goal is to produce a signal that can be transmitted easily and decoded to
reproduce the original digital data. Modems can be used over any means of transmitting analog
signals, from driven diodes to radio.


29. State the types of MODEM
The types of available modems include analog, digital subscriber line (DSL), cable and
Integrated Services Digital Network (ISDN). Analog modems are used for dial-up connections.
DSL and cable are high-speed broadband connections. ISDN modems transfer information in
channels of 64 kilobits per second (Kpbs) which can be combined for higher speeds. TYPES:
1.Standard Modems
Most standard modems today are either internal or external.

10. 2.Fax Modems
These allow you to send and receive faxes.
3.Intelligent Modems
Intelligent modems are more expensive modems that contain internal read only memory
(ROM
4.Short Haul Modems
Short Haul modems provide transmission of data at medium to high rate in either
direction (full duplex).
5.Wireless Modems
Wireless modems transmit the data signals through the air instead of by using a cable
6.Cable Modems
When cable was first introduced, it was designed for rural areas with poor reception
7.Total Control Enterprise Network Hub - T1 Interface & Modems
A dedicated T1 is often considered the entry-level connection for business Internet
access.
8.PCMCIA Modems
Another type of modem is PCMCIA modems that are build specifically for the
PCMCIA slot in a laptop
30.WHAT IS DSL?
Digital Subscriber Line (DSL) is a family of technologies that provides digital data transmission
over the wires of a local telephone network. DSL originally stood for digital subscriber loop. In
telecommunications marketing, the term Digital Subscriber Line is widely understood to mean
Asymmetric Digital Subscriber Line (ADSL), the most commonly installed technical variety of
DSL. DSL service is delivered simultaneously with regular telephone on the same telephone line.
This is possible because DSL uses a higher frequency. These frequency bands are subsequently
separated by filtering.
31. WHAT IS ADSL?
Asymmetric Digital Subscriber Line (ADSL) is one form of the Digital Subscriber Line
technology, a data communications technology that enables faster data transmission over copper
telephone lines than a conventional voice band modem can provide. It does this by utilizing
frequencies that are not used by a voice telephone call.[1] A splitter, or DSL filter, allows a

11. single telephone connection to be used for both ADSL service and voice calls at the same time.
ADSL can generally only be distributed over short distances from the central office, typically
less than 4 kilometers (2 mi),[2] but has been known to exceed 8 kilometers (5 mi) if the
originally laid wire gauge allows for farther distribution
32. WHAT ARE SOME AD COMMANDS
General at commands
AT - Gets the modem's attention; this prefix must be included in all commands unless otherwise
noted
+++ - Switches the modem from data to command state; this command is not proceeded by AT.
A - Instructs the modem to attempt to answer a call.
A/ - Re-executes the last modem executed command; this is not proceeded by AT.
Bn - sets the operation standard 0=CCITT, 1=Bell
Cn - Turns the modem transmit carrier signal on and off 0=turn off the modem transmit carrier
signal during normal operation; 1=Turn on modem transmit carrier signal during normal
operation.
Dn - Dials the number, n; T - Touch-Tone dialing; P - Pulse dialing; , - pause 2 seconds; @ -
Wait for 5 seconds of silence; R - Dial an originate-only modem; S=n - Dial one of four stored
telephone numbers; : - Return to command mode after dialing; ! - Go on hook for 1/2 second.
En - Turns the command echo feature on/off so that your commands either are displayed or are
not displayed on the screen 0=off, 1=on.
Hn - Causes the modem to hang up or pick up when in data mode 0=hang up, 1=pick up.
33. WHAT IS THE USE OF Z COMMAND AND M COMMAND IN MODEM?
Z command is used for reset and M command is used for mute.
Standards are available ATA1, ATA2, ATA3, ATA4, ATA5.
34. Give some networking devices:
Gateway, Router, Bridge, Switch, Hub & Repeater

12. UNIT-3
1. Sate the layout of keyboard.
The layout of keyboard are
1.83key - PC /CT keyboard.
2.84key - AT keyboard.
3.101 key - Enhanced 101 key keyboard.
4.104 key.
2.Difference between foam element switch and membrane switch.







3. Draw a neat diagram for pure mechanical switch.
Refer the notes
4. How many keys are there in XT keyboard?
XT means extended technology.There are 83 keys in the XT keyboard.
5. What is difference between 101 and 104 keyboard?
The difference between 101 and 104 keyboard is the addition of three keys
namely Two windows keys which is located between the CTRL and ALT keys on both sides and
an Application key on the right side, next to the window key.
6.How many function keys are 83 key keyboard and how they are arranged?
There are 10 function keys f1 to f10. They are arranged on the left side of the keyboard.
FOAM ELEMENT MEMBRANE SWITCH
Similar to pure mechanical switches in so
far they use an electric circuit between
each key and the circuit board below a
spring to pop the key back up. Here each
keytop is connected with a cushion of
foam gives the keyboard softier, quieter
and more cushiony feeling.

The most basic mechanical switch design is
one which depressing the key forces metal
contacts together, completing the circuit. A
spring forces the key back up to tis original
position. The nature of the spring
mechanism used in most keyboards.

13. 7. Difference unidirectional and bidirectional.
Unidirectional Bidirectional
When the communication is between only
keyboard and the computer’s motherboard
then it is unidirectional.
When the communication is between
keyboard and the computer’s motherboard
and vice versa then it is bidirectional.
Eg.83 key keyboard Eg. AT keyboard
8. Which is said to be inverted T keys ?
Cursor keys are said to be inverted T keys.
9.Give the types of keys in the keyboard.
The types of keys in the keyboard are alpha numeric keys, functional keys ,control key,
alt key, cursor key, escape key, space bar key, print screen, etc.,
10. State the types of key switches.
There are four types of key switches. They are
1. Pure mechanical switch.
2. Foam element.
3. Rubber dome switch.
4. Membrane switch.
11. State the difference between ball mouse and track ball mouse with diagram.
BALL MOUSE TRACK BALL MOUSE
The ball-mouse replaced the external wheels
with a single ball that could rotate in any
direction and came as part of the hardware
package of the Xerox Alto computer.
Users rotate a large ball in the mouse with their
fingertips instead of moving the mouse itself.
Bill English invented the so-called ball mouse
in the 1972 while working for Xerox PARC
The first trackball mouse was invented in 1991
by Logitech, and was launched with the Apple
Power book.
12. What is chopper wheel?
In ball mouse, Perpendicular chopper wheels housed inside the mouse's body chopped
beams of light on the way to light sensors, thus detecting in their turn the motion of the
ball.
13. State the advantage of optical mouse compared
To the auto mechanical mouse.

14. Optical mice supporters claim that optical rendering works better than mechanical mice,
that it requires no maintenance and that optical mice last longer due to having no moving
parts. Optical mice do not normally require maintenance other than removing debris that
might collect under the light-emitter. Supporters of mechanical mice point out that
optical mouse generally cannot track on glossy and transparent surfaces.
14. Define printer.
A computer printer, or more commonly just a printer, is a device that produces a hard
copy (permanent human-readable text and/or graphics) of documents stored in electronic
form, usually on physical print media such as paper or transparencies. A printer which is
combined with a scanner can essentially function as a photocopier. The printing speed of
early printers was measured in units of characters per second. More modern printers
are measured in pages per minute.
15.State the types of printer.
There are 9 types of printer they are
1.Toner-based printers
2.Liquid inkjet printers
3.Solid Ink printers
4.Dye-sublimation printers
5.Typewriter-derived printers
6.Teletypewriter-derived printers
7.Daisy wheel printers
8.Dot-matrix printers
9.Line printers
16. What is CPS,PPM,FF,LF?
CPS-Character per second
Ppm-Paper per minute
FF-form field
LF-line field
17. Define Dye sublimation printers?

15. A dye-sublimation printer (or dye-sub printer) is a printer which employs a printing
process that uses heat to transfer dye to a medium such as a plastic card, paper or canvas. The
process is usually to lay one color at a time using a ribbon that has color panels.
18. What are the 9 types of printers?
1.Toner-based printers
2.Liquid inkjet printers
3.Solid Ink printers
4.Dye-sublimation printers
5.Typewriter-derived printers & 6. .Teletypewriter-derived printers
7.Daisy wheel printers
8.Dot-matrix printers
9.Line printers

19. Define Toner-based printers?
Toner-based printers work using the Xerographic principle that is at work in most
photocopiers i.e. by adhering toner to a light-sensitive print drum, then using static electricity to
transfer the toner to the printing medium to which it is fused with heat and pressure.
20. What are the functions of Joystick?
Most joysticks are two-dimensional, having two axes of movement (similar to a mouse),
but one and three-dimensional joysticks do exist.
A joystick is generally configured so that moving the stick left or right signals movement
along the X axis, and moving it forward (up) or back (down) signals movement along the Y axis.
In joysticks that are configured for three-dimensional movement, twisting the stick left (counter-
clockwise) or right (clockwise) signals movement along the Z axis.
21. Define CGA?
CGA means Color Graphics Adapter
The standard IBM CGA graphics card was equipped with 16 kilobytes of video memory, and
could be connected either to a NTSC-compatible monitor or TV or to a dedicated RGBI CRT
monitor.
22. What are the colour codes for blue and yellow?
The colour code for blue is #0000AA

16. The colour code for yellow is #FFFF55
23. Define SVGA?
Super Video Graphics Array, almost always abbreviated to Super VGA or
just SVGA is a broad term that covers a wide range of computer display standards. , It was an
extension to the VGA standard.
24. What is the resolution rate for VGA?
The resolution rate for VGA is 640×480 pixels.
25. Give the color palette for CGA?
'''Full CGA 16-color palette'''
0 — black
#000000
8 — (dark) gray
#555555
1 — blue
#0000AA
9 — bright blue
#5555FF
2 — green
#00AA00
10 — bright green
#55FF55
3 — cyan
#00AAAA
11 — bright cyan
#55FFFF
4 — red
#AA0000
12 — bright red
#FF5555
5 — magenta
#AA00AA
13 — bright magenta
#FF55FF
6 — brown
#AA5500
14 — yellow
#FFFF55
7 — white (light gray)
#AAAAAA
15 — bright white
#FFFFFF

26. Define Scanner?

17. A scanner is a device that optically scans images, printed text, handwriting, or an object,
and converts it to a digital image. Scanner consisting of a rotating drum with a single photo
detector at a standard speed of 60 or 120 rpm (later models up to 240 rpm).
27. State the types of Scanner?
There are 4 types of scanner:
1. Drum; 2.Flatbed; 3.Film; 4.Hand-held
28. Define Hand scanner?
Hand held document scanners are manual devices that are dragged across the surface of
the image to be scanned. Scanning documents in this manner requires a steady hand, as an
uneven scanning rate would produce distorted images - a little light on the scanner would
indicate if the motion was too fast.
29. Define PMT?
PMT means Photomultiplier Tubes. Drum scanners capture image information with
photomultiplier tubes (PMT).
30. Define CCD?
The charge-coupled device (CCD) arrays found in flatbed scanners and inexpensive film
scanners. CCD type scanners typically contain three rows (arrays) of sensors with red, green, and
blue filters.

18. UNIT-4
1. which is said to be small, light weight, removable drive?
USB flash drive is said to be small ,light weight, removable drive.
2. How does USB flash drive work?

NAND flash memory wiring and structure on silicon
Flash_cell_structure
NAND flash uses floating-gate transistors, but they are connected in a way that
resembles a NAND gate: several transistors are connected in series, and only if all word
lines are pulled high (above the transistors' VT) is the bit line pulled low. These groups
are then connected via some additional transistors to a NOR-style bit line array.
To read, most of the word lines are pulled up above the VT of a programmed bit, while
one of them is pulled up to just over the VT of an erased bit. The series group will
conduct (and pull the bit line low) if the selected bit has not been programmed.
Despite the additional transistors, the reduction in ground wires and bit lines allows a
denser layout and greater storage capacity per chip. NAND flash uses tunnel injection for
writing and tunnel release for erasing. NAND flash memory forms the core of the
removable USB storage devices known as USB flash drives, as well as most memory
card formats and solid-state drives available today.
Male type-A USB connector – provides a physical interface to the host computer.
USB mass storage controller – implements the USB host controller. The controller
contains a small microcontroller with a small amount of on-chip ROM and RAM.
NAND flash memory chip – stores data. NAND flash is typically also used in digital
cameras.
Crystal oscillator – produces the device's main 12 MHz clock signal and controls the
device's data output through a phase-locked loop.

3. What are the components of USB flash drives ?
Essential components
There are typically four parts to a flash drive:
 Male type-A USB
connector – provides a physical interface to the host computer.

19.  USB mass storage
controller – implements the USB host controller. The controller contains a
small microcontroller with a small amount of on-chip ROM and RAM.
 NAND flash memory
chip – stores data. NAND flash is typically also used in digital cameras.
 Crystal oscillator –
produces the device's main 12 MHz clock signal and controls the device's data output
through a phase-locked loop.
Additional components
The typical device may also include:
 Jumpers and test pins – for testing during the flash drive's manufacturing or
loading code into the microprocessor.
 LEDs – indicate data transfers or data reads and writes.
 Write-protect switches – Enable or disable writing of data into memory.
 Unpopulated space – provides space to include a second memory chip. Having
this second space allows the manufacturer to use a single printed circuit board for
more than one storage size device.
 USB connector cover or cap – reduces the risk of damage, prevents the ingress of
fluff or other contaminants, and improves overall device appearance. Some flash
drives use retractable USB connectors instead. Others have a swivel arrangement so
that the connector can be protected without removing anything.
 Transport aid – the cap or the body often contains a hole suitable for connection
to a key chain or lanyard. Connecting the cap, rather than the body, can allow the
drive itself to be lost.
 Some drives offer expandable storage via an internal memory card slot, much like
a memory card reader

4. What are the Advantages of USB flash drives?
 Data stored on flash drives is impervious to scratches and dust.
 Flash drives are mechanically very robust making them suitable for transporting data
from place to place and keeping it readily at hand.
 Flash drives also store data densely compared to many removable media. In mid-
2009, 256 GB drives became available, with the ability to hold many times more data
than a DVD or even a Blu-ray disc.
 Compared to hard drives, flash drives use little power, have no fragile moving parts,
and for low capacities are small and light.
 Flash drives implement the USB mass storage device class so that most
modern operating systems can read and write to them without installing device
drivers.
 The flash drives present a simple block-structured logical unit to the host operating
system, hiding the individual complex implementation details of the various

20. underlying flash memory devices. The operating system can use any file system or
block addressing scheme. Some computers can boot up from flash drives.
 Specially manufactured flash drives are available that have a tough rubber or metal
casing designed to be waterproof and virtually "unbreakable".
 These flash drives retain their memory even after being submerged in water.

5. What do you mean by tape drive?
A tape drive is a data storage device that reads and writes data on a magnetic tape. It
is typically used for offline, archival data storage. Tape media generally has a favorable unit
cost and long archival stability. A tape drive provides sequential access storage, unlike a disk
drive, which provides random access storage. A disk drive can move its read/write head(s) to
any random part of the disk in a very short amount of time, but a tape drive must spend a
considerable amount of time winding tape between reels to read any one particular piece of
data. As a result, tape drives have very slow average seek times. Despite the slow seek time,
tape drives can stream data to and from tape very quickly. For example, modern LTO
(LINEAR TAPE OPEN) drives can reach continuous data transfer rates of up to 80 MB/s,
which is as fast as most 10,000 RPM hard disks.
6. Can you store the text data into tape drive?
No, we cannot store text data into tape drives.
7.Who invented floppy disk drive?
The floppy disk drive (FDD) was invented at IBM by Alan Shugar.
8.What is meant by floppy disk drive?
The floppy disk drive (FDD) was the primary means of adding data to a computer
until the CD-ROM drive became popular.
9.How the floppy disk is made up of?
The floppy disk is made up of metal-coated plastic similar to audio cassette tape.
10.What are the different size of floppy disk?
(i). 8 inch floppy disk
(ii). 5.25 inch floppy disk
(iii). 3.5inch floppy disk
11.what is meant by stepper motor?

21. Stepper motor makes a precise number of stepped revolutions to move the read/write head
assembly to the proper track position. The read/write head assembly is fastened to the stepper
motor shaft.
12.Write about read/write head?
Located on both sides of a diskette, they move together on the same assembly. The heads are not
directly opposite each other in an effort to prevent interaction between write operations on each
of the two media surfaces. The same head is used for reading and writing, while a second, wider
head is used for erasing a track just prior to it being written. This allows the data to be written on
a wider "clean slate," without interfering with the analog data on an adjacent track.
13.Define drive motor?
A very small spindle motor engages the metal hub at the center of the diskette, spinning it at
either 300 or 360 rotations per minute (RPM).
14.what is meant by track and sectors?
The disk has many concentric tracks on each side. Each track is divided into smaller segments
called sectors, like slices of a pie.
15.Define write protect notch?
The read/write heads do not touch the diskette media when the heads are traveling between
tracks. Electronic optics check for the presence of an opening in the lower corner of a 3.5-inch
diskette (or a notch in the side of a 5.25-inch diskette) to see if the user wants to prevent data
from being written on it.
16 . What is meant by MFM?
Modified Frequency Modulation, commonly MFM, is a line code used by most floppy disk
formats, notably by most CP/M machines, as well as PCs running DOS.
17. What is meant by RLL?
Run Length Limited codes, or RLL codes, are widely used in hard disk drives, Hi-MD
Minidisks, (and notably digital optical discs, such as CD, DVD and Blue Ray discs) to prevent
long stretches of no transitions, and therefore decoding uncertainty, from creeping in.
18. How data stored in CD?
Data is stored on the disc as a series of microscopic indentations ("pits", with the gaps between
them referred to as "lands").
19. What is the thickness of CD?

22. The thickness of CD is 1.2 mm thick.
20. What is the diameter of CD?
The diameter of CD is 120mm.

UNIT-5
1.Define in circuit emulator?
An in-circuit emulator (ICE) is a hardware device used to debug the software of an embedded
system. It was historically in the form of bond-out processor which has many internal signals
brought out for the purpose of debugging. These signals provided information about the state of
the processor.
2.Define logical analyzer?
A logic analyzer is an electronic instrument that displays signals in a digital circuit that are too
fast to be observed and presents it to a user so that the user can more easily check the operation
of the digital system with precision.
3.Define multimeter?
A multimeter or a multitester, also known as a volt/ohm meter or VOM, is an electronic
measuring instrument that combines several measurement functions in one unit. A typical
multimeter may include features such as the ability to measure voltage, current and resistance.
4. What are the types of multimeter?
There are two types of multimeter. they are,
1. Analog multimeter,
2. Digital multimeter.
5. What is meant by VOM and DMM?
VOM means Volt Ohm Meter,
DMM means Digital multimeter.

6. What is the Command used for Help?
The Command used for help is H
7. What is the Command used for Reset?

23. The Command used for Reset is X
8. What is the use of Logic analyzer?
A logic analyzer displays signals in a digital circuit that are too fast to be observed by a
human being and presents it to a user so that the user can more easily check correct operation of
the digital system.
9. Define Cathode ray tube monitor?
Most monitors (computer screens) use cathode ray tubes (or CRT for short), which are glass
vacuum tubes into which an electron gun emits a flow of electrons guided by an electrical field
towards a screen covered in small phosphorescent elements.

The electron gun is made up of a cathode, a negatively charged metallic electrode, and one or
more anodes (positively charged electrodes). The cathode emits the electrons attracted by the
anode.
10. What do you meant by trigger?
To provide a more stable trace, modern oscilloscopes have a function called the trigger.
When using triggering, the scope will pause each time the sweep reaches the extreme right side
of the screen. The scope then waits for a specified event before drawing the next trace. The
trigger event is usually the input waveform reaching some user-specified threshold voltage in the
specified direction (going positive or going negative).
11. What are the types of trigger?
Types of trigger include:
 External trigger, a pulse from an external source connected to a dedicated input on the
scope.
 Edge trigger, an edge-detector that generates a pulse when the input signal crosses a
specified threshold voltage in a specified direction.

24.  Video trigger, a circuit that extracts synchronizing pulses from video formats such as
PAL and NTSC and triggers the time base on every line, a specified line, every field, or
every frame. This circuit is typically found in a waveform monitor device.
 Delayed trigger, which waits a specified time after an edge trigger before starting the
sweep. No trigger circuit acts instantaneously, so there is always a certain delay, but a
trigger delay circuit extends this delay to a known and adjustable interval. In this way, the
operator can examine a particular pulse in a long train of pulses.

12. Define Signature analyzer?
Signature Analysis is an easy-to-use and highly accurate technique for identifying faulty
logic nodes.
 It is one specialized class of test instruments used in product development,
production, and field services.
 It can be very effective in troubleshooting microprocessor systems by converting in
troubleshooting microprocessor systems by converting serial data, streams present on
microprocessor system logic nodes into four-digit “signatures” and these signatures
tell whether or not the nodes is performing properly.

13. What are the characters used in signature analyzer?
The characters used in signature analyzer are 0-9, A, H, P etc.
14. What are the buttons available in Signature Analyser?
Start, Stop, Clock & Hlt.
15. What is the measure or unit for Temperature?
Celcius Or Fahrenheit is the measure for temperature.