Why Learning The OSI Model Is Important
There's nothing I enjoy more than teaching Cisco technologies, especially CCNA candidates. Whether it's in-person or online, everyone's excited to be there. There's a sense of anticipation in the air, and everyone is ready to work hard, get their hands on the racks of Cisco routers and switches I have available... ... and then I break out the OSI model chart. Chins slump. People sigh, or at least wish they hadn't ordered decaf that morning. Okay, it's not that bad. But it does temper the excitement a little. I always get a sense of "why can't we just hurry up and get on the routers and switches? Why do we have to learn this dry stuff?" One reason is that Cisco demands you know the OSI model inside and out for both the Intro and ICND exams. You have to admit that's a pretty good reason, but still, students find the OSI model information to be very dry. I understand that, because I've been there. My first exposure to the OSI model was actually in a Novell "Networking Technologies" class, and man, was that chart ever dry. They crammed every known protocol (and some unknown ones, I think) into the OSI model. It looked like a giant jigsaw puzzle, and the real problem is that I didn't know what the heck most of that stuff was. So I dutifully attempted to memorize this massive chart. I managed to pass the exam, but I wondered what all that effort had really been for. It's not like you sit around in a server room or wiring closet and discuss the OSI model. As a CCNA candidate, you don't have to worry about all the protocols I memorized way back when, but you do have to know what happens at each layer. Which leads to this question: "If I work with routers and switches, why do I have to know about all the other layers? Don't routers and switches just work at layer 2 and 3?" Yes, switches work at Layer 2 and routers at Layer 3. But to truly understand networking, you've got to understand what happens at the other layers. Why? Most network administrators and engineers are going to spend a lot more time troubleshooting than installing. That's just the way it is. And to troubleshoot effectively, you've got to know what's going on at all layers of the OSI model, not just layers 2 and 3. As someone who's done a lot of hiring and conducted a great many job interviews, I can tell you that the ability to troubleshoot is the number one quality I look for. That's why I tell CCNA and CCNP candidates that they've got to get all the hands-on practice they can; while I understand the importance of theory, the only way to develop troubleshooting ability is to work on the real deal. No simulator program is going to teach you how to troubleshoot. Additionally, the only way to truly develop your troubleshooting abilities is to know what's going on over the entire network, not just the routers and switches. Troubleshooting always starts at Layer 1; if you don't find a problem at the Physical layer, and everything's fine with your routers and switches, how are you going to continue troubleshooting if you don't know what the next steps are as data moves closer to the end user? So when it comes to the OSI model, don't just give it a quick once-over and move on to the fun stuff in your CCNA studies. The tangible benefit of passing your exams is great, but it's the hidden benefit of developing your own troubleshooting methodology that makes mastering the OSI model worthwhile.

COMPUTER ARCHITECTURE QUESTIONS AND ANSWERS

Can you be able to identify between Straight- through and Cross- over cable
wiring?
Straight-through is type of wiring that is one to to one connection Cross-
over is type of wiring which those wires are got switchedWe use
Straight-through cable when we connect between NIC Adapter and Hub. Using
Cross-over cable when connect between two NIC Adapters or sometime between
two hubs.

What is cache memory?
Cache memory is random access memory (RAM) that a computer microprocessor
can access more quickly than it can access regular RAM. As the
microprocessor processes data, it looks first in the cache memory and if it
finds the data there (from a previous reading of data), it does not have to
do the more time-consuming reading of data from larger memory.(cache memory
is used between the c.p.u and the ram to access dta fastly)

What is hard disk and what is its purpose?
Hard disk is the secondary storage device, which holds the data in bulk, and
it holds the data on the magnetic medium of the disk.Hard disks have a hard
platter that holds the magnetic medium, the magnetic medium can be easily
erased and rewritten, and a typical desktop machine will have a hard disk
with a capacity of between 10 and 40 gigabytes. Data is stored onto the disk
in the form of files.

Where's MBR located on the disk?
Master Boot Record is located in sector 0, track 0, head 0, cylinder 0 of
the primary active partition.

What's the speed and device maximum specs for Firewire?
IEEE 1394 (Firewire) supports the maximum of 63 connected devices with
speeds up to 400 Mbps.

What's the difference between L1 and L2 cache?
Level 1 cache is internal to the chip, L2 is external. L1 Cache is of Higher
speed than that of L2 Cache.

Name the processor lines of two major manufacturers?
High-end: Intel - Pentium (II, III, 4), AMD - Athlon. Low-end: Intel -
Celeron, AMD - Duron. 64-bit: Intel - Itanium 2, AMD - Opteron

Where does CPU Enhanced mode originate from?
Intel's 80386 was the first 32-bit processor, and since the company had to
backward-support the 8086. All the modern Intel-based processors run in the
Enhanced mode, capable of switching between Real mode (just like the real
8086) and Protected mode, which is the current mode of operation.

Where does the Real mode on the CPU come from?
The original 8086, which only had 1 MB of memory. This megabyte is split
into low memory for IRQ tables, application memory and high memory.

How do you clear CMOS password?
Since CMOS is a special chip with its own battery, the best way to clear out
a CMOS chip is to disconnect it from its power supply.

What are the basic expansion card types?
ISA and PCI, ISA can be used only on XT, AT and ATX boards. The industry now
considers ISA obsolete.

What is a compiler?
Compiler is used to translate the high-level language program into machine
code at a time. It doesn.t require special instruction to store in a memory,
it stores automatically. The Execution time is less compared to Interpreter.

What is NV-RAM?
Nonvolatile Read Write Memory, also called Flash memory. It is also know as
shadow RAM.

What is called Scratch pad of computer?
Cache Memory is scratch pad of computer.

What is the difference between primary & secondary storage device?
In primary storage device the storage capacity is limited. It has a volatile
memory. In secondary storage device the storage capacity is larger. It is a
nonvolatile memory. Primary devices are: RAM / ROM. Secondary devices are:
Floppy disc / Hard disk.

What is meant by LATCH?
Latch is a D- type flip-flop used as a temporary storage device controlled
by a timing signal, which can store 0 or 1. The primary function of a Latch
is data storage. It is used in output devices such as LED, to hold the data
for display.

What is 1st / 2nd / 3rd / 4th generation processor?
The processor made of PMOS / NMOS / HMOS / HCMOS technology is called 1st /
2nd / 3rd / 4th generation processor, and it is made up of 4 / 8 / 16 / 32
bits.

Is the address bus unidirectional?
The address bus is unidirectional because the address information is always
given by the Micro Processor to address a memory location of an input /
output devices.

Difference between static and dynamic RAM?
Static RAM: No refreshing, 6 to 8 MOS transistors are required to form one
memory cell, Information stored as voltage level in a flip flop.
Dynamic RAM: Refreshed periodically, 3 to 4 transistors are required to form
one memory cell, Information is stored as a charge in the gate to substrate
capacitance.

Design Goals Of a Computer Architecture
The most common goals in computer architecture revolve around the tradeoffs
between cost and performance (i.e. speed), although other considerations,
such as size, weight, reliability, feature set, expandability and power
consumption, may be factors as well

What are Pipelining Issues?
Pipelining increases the CPU instruction throughput - the number of
instructions completed per unit of time. But it does not reduce the
execution time of an individual instruction. In fact, it usually slightly
increases the execution time of each instruction due to overhead in the
pipeline control.
The increase in instruction throughput means that a program runs faster and
has lower total execution time.

Limitations on practical depth of a pipeline arise from:
Pipeline latency. The fact that the execution time of each instruction does
not decrease puts limitations on pipeline depth;
Imbalance among pipeline stages. Imbalance among the pipe stages reduces
performance since the clock can run no faster than the time needed for the
slowest pipeline stage;
Pipeline overhead. Pipeline overhead arises from the combination of pipeline
register delay (setup time plus propagation delay) and clock skew.
Once the clock cycle is as small as the sum of the clock skew and latch
overhead, no further pipelining is useful, since there is no time left in
the cycle for useful work.

How do you detect if two 8-bit signals are same?
XOR each bits of A with B (for eg A[0] xor B[0] ) and so on. the o/p of 8
xor gates are then given as i/p to an 8-i/p nor gate. if o/p is 1 then A=B.

Difference between RISC and CISC?
RISC-Means Reduced Instruction Set Computer.a Risc system has reduced number
of instructions and more importantly it is load store architecture were
pipelining can be implemented easily.Eg.ATMEL AVR
CISC-Means Complex instruction set architecure.A CISC system has complex
instructions such as direct addition between data in two memory
locations.Eg.8085

What is pipelining?
A technique used in advanced microprocessors where the microprocessor begins
executing a second instuction before the first has been completed. That is,
several instructions are in the pipeline simultaneously, each at a different
processing stage.

What is Virtual Memory?
Virtual memory is a concept that, when implemented by a computer and its
operating system, allows programmers to use a very large range of memory or
storage addresses for stored data. The computing system maps the
programmer's virtual addresses to real hardware storage addresses. Usually,
the programmer is freed from having to be concerned about the availability
of data storage.
In addition to managing the mapping of virtual storage addresses to real
storage addresses, a computer implementing virtual memory or storage also
manages storage swapping between active storage (RAM) and hard disk or other
high volume storage devices. Data is read in units called "pages" of sizes
ranging from a thousand bytes (actually 1,024 decimal bytes) up to several
megabyes in size. This reduces the amount of physical storage access that is
required and speeds up overall system performance.

Computer Peripherals Price List Jan 2007

 PROCESSORS PRICE LIST

AMD PROCESSORS:-

SEMPRON
Sempron 3000+ (1.8GHz 128KB L2 cache 754) Rs1900
Sempron 3200+ (1.8GHz 128KB L2 cache AM2) Rs2200

ATHLON 64
Athlon 64 3000+ (1.8GHz 512KB L2 cache AM2, 939) Rs2675
Athlon 64 3200+ (2.0GHz 512KB L2 cache AM2, 939) Rs3250
Athlon 64 3500+ (2.2GHz 512KB L2 cache AM2, 939) Rs3800
Athlon 64 3800+ (2.4GHz 512KB L2 cache AM2, 939) Rs4300

ATHLON 64 X2
Athlon 64 X2 3600+ (2.0GHz 512KB L2 cache AM2) Rs5300
Athlon 64 X2 3600+ (1.9GHz 1MB L2 cache AM2) Rs5900
Athlon 64 X2 3800+ (2.0GHz 1MB L2 cache AM2) Rs6300
Athlon 64 X2 4000+ (2.1GHz 1MB L2 cache AM2) Rs7000
Athlon 64 X2 4200+ (2.2GHz 1MB L2 cache AM2) Rs7700
Athlon 64 X2 4400+ (2.3GHz 1MB L2 cache AM2) Rs9000
Athlon 64 X2 4600+ (2.4GHz 1MB L2 cache AM2) Rs9800
Athlon 64 X2 4800+ (2.5GHz 1MB L2 cache AM2) Rs11200
Athlon 64 X2 5000+ (2.6GHz 1MB L2 cache AM2) Rs13100
Athlon 64 X2 5200+ (2.6GHz 2MB L2 cache AM2) Rs13575
Athlon 64 X2 5400+ (2.8GHz 1MB L2 cache AM2) Rs22150
Athlon 64 X2 5600+ (2.8GHz 2MB L2 cache AM2) Rs23250
Athlon 64 X2 5800+ (3.0GHz 1MB L2 cache AM2) Rs27500
Athlon 64 X2 6000+ (3.0GHz 2MB L2 cache AM2) Rs28450

OPTERON SERIES
OPTERON 144 (1.8GHz 1MB L2 cache 939) Rs4100
OPTERON 146 (2.0GHz 1MB L2 cache 939) Rs4700

OPTERON X2 SERIES
OPTERON X2 165 (1.8GHz 2MB L2 cache 939) Rs7900

INTEL PROCESSORS:-

CELERON D (775)
326 (256K L2 cache 2.53GHz 533MHz FSB) Rs1900
331 (256K L2 cache 2.66Ghz 533MHz FSB) Rs1950
336 (256K L2 cache 2.80Ghz 533MHz FSB) Rs2050
341 (256K L2 cache 2.93Ghz 533MHz FSB) Rs2150

PENTIUM 4 (775)
506 (1MB L2 cache 2.66Ghz 533MHz FSB) Rs3300
511 (1MB L2 cache 2.80Ghz 533MHz FSB) Rs3400
516 (1MB L2 cache 2.93Ghz 533MHz FSB) Rs3500
531 (1MB L2 cache 3.00Ghz 800MHz FSB) Rs3600

PENTIUM D (775)
820 (2MB L2 cache 2.80Ghz 800MHz FSB) Rs4300
915 (4MB L2 cache 2.80Ghz 800MHz FSB) Rs4900
925 (4MB L2 cache 3.00Ghz 800MHz FSB) Rs5700

CORE 2 DUO (775)
E4300 (2MB L2 cache 1.80Ghz 800MHz FSB) Rs7300
E6300 (2MB L2 cache 1.86Ghz 1066MHz FSB) Rs8300
E6400 (2MB L2 cache 2.13Ghz 1066MHz FSB) Rs10500
E6600 (4MB L2 cache 2.40Ghz 1066MHz FSB) Rs14900
E6700 (4MB L2 cache 2.66Ghz 1066MHz FSB) Rs23800

MOTHERBOARDS PRICE LIST

MOTHERBOARDS FOR AMD CPU (Socket 754)

ASUS K8V-MX Rs2100
ASUS K8V-M ULTRA Rs2300
GIGABYTE K8V800M-L Rs2000
MERCURY K8V800 Rs2100
BIOSTAR K8M 800 Rs2200

MOBOS FOR AMD CPU (Socket 939)

ASUS A8N VM Rs3700
ASUS A8N VM CSM Rs4100
ASUS A8N-E Rs5200
ASUS A8N-SLI Rs6300
GIGABYTE RS482M2-IL Rs3000
GIGABYTE K8N51GMF-9 Rs3200

MOBOS FOR AMD CPU (Socket AM2)

ASUS M2NPV-VM Rs4000
ASUS M2N-MX Rs4100
ASUS M2NPV-MX Rs4300
ASUS M2N4 SLI Rs5500
ASUS M2N32-SLI DLX Rs11500
GIGABYTE RS482 Rs4000
MSI K9NGM2 Rs4200

MOBOS FOR INTEL CPU (Socket 775)

INTEL D101GGC Rs3700
ASUS P5RD1-VM Rs2900
GIGABYTE 915 Rs3100
INTEL 915 GAVL Rs4300

MOBOS FOR INTEL CPU (Socket 775) DDR2

INTEL D102GGC2 Rs3900
ASUS P5RD2 VM Rs3100
D-LINK 915 Rs3900

MOBOS FOR INTEL CORE 2 DUO CPU (Socket 775)

GIGABYTE GA-945GM-S2 Rs4500
GIGABYTE GA-965P-DS3 Rs8000
GIGABYTE GA-965P-DQ6 Rs10800
INTEL D946GSIL Rs4500
INTEL D965RY Rs6300
INTEL D965WH Rs7100
INTEL D975XBX2 Rs12400
MSI P965 Neo-F Rs5500
MSI P965 PLATINUM Rs6700
MSI D975X PLATINUM V.2 Rs9000
ASUS P5LD2-VM SE Rs4100
ASUS P5B-VM Rs6500
ASUS P5B DLX Rs9900
ASUS P5WDH DLX Rs11200

HARD DISK DRIVES (SEAGATE\SAMSUNG) PRICE LIST

80 GB (7200 RPM) Rs1950
120 GB (7200 RPM) Rs2400
160 GB (7200 RPM) Rs2600
200 GB (7200 RPM) Rs3100
250 GB (7200 RPM) Rs3500
300 GB (7200 RPM) Rs4400
320 GB (7200 RPM) Rs4700

80 GB SATAII Rs2050
120 GB SATAII Rs2400
160 GB SATAII Rs2700
200 GB SATAII Rs3150
250 GB SATAII Rs3600
300 GB SATAII Rs4500
320 GB SATAII Rs4700

RAM PRICE LIST

DDR 333/400MHz :-

TRANSCEND 256 MB Rs1400
TRANSCEND 512 MB Rs2500
TRANSCEND 1 GB Rs5000

KINGSTON 256 MB Rs1600
KINGSTON 512 MB Rs2800
KINGSTON 1 GB Rs5400

DDR2 533/667MHz :-

TRANSCEND 256 MB Rs1200
TRANSCEND 512 MB Rs2300
TRANSCEND 1 GB Rs4500

CORSAIR 256 MB Rs1400
CORSAIR 512 MB Rs2700
CORSAIR 1 GB Rs5200

GRAPHIC CARDS PRICE LIST

PCI-E 16X :

XFX 7300GS 512MB Rs3200
XFX 7300GT 256MB Rs4500
XFX 7600GS 512MB Rs5800
XFX 7600GT 256MB Rs9100
XFX 7900GS 512MB Rs12100
XFX 7900GT 256MB Rs15200
XFX 7950GT 512MB Rs19000
XFX 8800GTS 320MB Rs22300
XFX 8800GTS 640MB Rs25300
XFX 8800GTX 768MB Rs32300

CRT MONITERS PRICE LIST

SAMSUNG 15" 591S Rs3700
SAMSUNG 17" 793S Rs4500
SAMSUNG 17" FLAT 798MB Rs5700
LG 15" 500G Rs3700
LG 17" 700E Rs4500
LG 17" FLAT E700SH Rs5800
PHILIPS 15" 105 Rs3600
PHILIPS 17" 107S Rs4300
VIEWSONIC 17" FLAT Rs5900

LCD/TFT PRICE LIST

L.G. 15" L1520B Rs8200
L.G. 17" L1752S Rs10100
L.G. 19" L1952S Rs13400
SAMSUNG 15" 540N Rs8200
SAMSUNG 17" 740N Rs9900
SAMSUNG 19'' 940BW Rs13800
BENQ 15'' FP51G Rs7800
BENQ 17'' FP71E+ Rs8800
BENQ 19'' FP92W Rs12600
PHILIPS 15" 150S7FB Rs8100
VIEWSONIC 15" VA503M Rs7900
VIEWSONIC 17" VA712 Rs9200
VIEWSONIC 17" VA1703 Rs10200
VIEWSONIC 19" VX1935VM Rs13000
SONY 15" SDM-S53 Rs9000
SONY 17" SDM-E76D Rs12000
SONY 19" SDM-E96D Rs16700
ACER 15" 1500S Rs8000
ACER 17" 1700S Rs9200
ACER 19" AL1916W Rs12900

OPTICAL DEVICE PRICE LIST

CD WRITERS
52x SONY Rs930
52x SAMSUNG Rs890
52x LG Rs880

COMBO DRIVE
SONY Rs1100
LG Rs1020
SAMSUNG Rs1000

DVD WRITERS
16 X SAMSUNG Rs1800
16 X SONY Rs1850
16 X SONY DRV820A Rs2100
16 X LG Rs1810
16 X LITEON Rs1900
16 X LITEON LIGHTSCRIBE Rs3000

SPEAKERS PRICE LIST

CREATIVE SPEAKERS
CREATIVE SBS-240 Rs400
CREATIVE SBS 2.1 Rs1100
CREATIVE SBS 5.1 Rs2200
CREATIVE INSPIRE 2.1 Rs1800
CREATIVE INSPIRE 4.1 Rs2400
CREATIVE INSPIRE 5.1 Rs3800
CREATIVE INSPIRE 6.1 Rs5200
CREATIVE INSPIRE 7.1 Rs6900

ALTECH LANCING SPEAKERS
ALTECH LANCING AVS-121I Rs1100
ALTECH LANCING VL-251 5.1 Rs4000
ALTECH LANCING ATP3 2.1 Rs2600

MODEMS PRICE LIST

56K INTERNAL PC-TEL Rs250
D-LINK 56K INTERNAL Rs400
D-LINK 56K EXT. Rs1300
DSL MODEM D-LINK Rs1400

CABINET PRICE LIST

I-BALL TOWER Rs1500
I-BALL CROWN Rs1600
I-BALL 441 Rs1625
I-BALL GRABIT Rs1650

SMPS PRICE LIST
ZEBRONICS PURE PLATINUM 360W Rs1600
ZEBRONICS PURE PLATINUM 460W Rs2200

TV TUNER/FM CARDS PRICE LIST

TV TUNER FRONTECH/INTEX Rs1150
TV TUNER FRONTECH/INTEX Ext. Rs1000
PIXEL VIEW PLAY TV PRO Rs1600
PINNACLE PCTV 50i Rs2300
TECH-COM EXT. TV TUNER FOR TFT/LCD Rs1900

UPS PRICE LIST

MICROTECH 600VA Rs1800
MICROTECH 800VA Rs2300
WIPRO 500VA Rs1600
WIPRO 600VA Rs2000
WIPRO 800VA Rs2500
APC 500VA Rs1995
APC 650VA Rs2700
FRONTECH 600 VA Rs1600
Cheers!!!

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