Combinational Circuits (Adder, Subtractor, Encoder, Decoder, and Multiplexer

Combinational Circuits

Definition: In simple terms a circuit in which output depends only on the inputs but not on the state of that circuit is known as combinational circuits.

We have different types of combinational circuits like Adder, Subtractor, Encoders, Decoders, Multiplexers and De-Multiplexers.There are lots of books you can follow to study these circuits, so there is no need of going  in-depth study of these circuits here, at this post I will give you some tricks or ideas how to use knowledge of these circuit in solving GATE problems, and how to create a circuit for a given function for these Adder, Subtractor, Encoders, Decoders, Multiplexers.Here is an applet which I have used in my Digital Logic post and again here I am presenting this applet again for all of you. Just use radio buttons which is here as "Gates1, Gates2, Full Adder ..." and get more practical experience about these circuits

NOTE-1: Any n-variable can be realized or implemented  using 2^(n-1)*1 MUX(multiplexer).

NOTE-2: Number of m*1 multiplexer required to form n*1 multiplexer is

here for fractional value of this log term we have to use the ceiling value of that fraction.

this formula is very helpful in solving such questions where you encounter such a question where you have to find number of small multiplexers need to create a larger multiplexers.

If no applet appears, you have to install the JRE of http://java.sun.com.

here it is a java applet for half adder if this is not being displayed in your browser install java in your browser.
for more digital circuit view this applets page for digital circuits 

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Add java applets in your blogger blog

ADD JAVA APPLETS IN YOUR BLOG

Hello reader if you are here it means you want to add some java applets in your blog post, if you have your domain its not a big deal for you to add java applets in your blog but if you are using some blog services like blogger which I am using you feel lots of problems because you do not have a directory to save java files over there, so you have to fetch java applets from other directories or another sites which is useful for your blog post. Here I am writing step by step process to add JAVA APPLETS into your blog.

Here it a code snippet:

<applet code="GatesApplet.class" codebase="http://www.chem.uoa.gr/applets/appletgates/" height="370" width="480">

here code="xxxxxxxxxxx" denotes the class which is the class file for the applet

here codebase= "xxxxxxxxxxxxx" denotes the directory where this applet is stored 

so if you are adding an applet or you can say fetching an app from a page you must find its class file and the directory where that applet is stored.

it means you have to know the codebase i.e the directory and code that is class file of that applet.

another thing is that the some times JAVA applets are stored in a archive file so in these case this code will work.

<applet archive="http://www.wireless-earth.de/applets/GDI/gatesim.jar" code="volladdierer.class" height="600" width="430"></applet></div>

this is another type of code in which applet is stored in a archive file hence you should first find that archive and then the whole code work like the last

one.

now here question arises how to how to find the archive, code or codebase for a perticular JAVA applet.

simple solution is that check the source file of that page using CTRL+U in your browser and then check for the code which is just similar to the code snippets given here and you are done.

Here the first snippet is the real code which i have used in blog post which is for digital logic gates.

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BOOTING OF AN OPERATING SYSTEM OR UNDERSTANDING OF HOW OS BOOTS

HOW OS BOOTS 

Hello every one here I am going to explain how operating system boots i.e what happens when we start our PC. This is a very large process and here I am presenting it in a short form.

When we power on the computer then it takes some time, until it gets power good signal and in this duration it sends a reset signal to CPU. Power good signal is a sign that shows that it is appropriate to start the booting sequence. The value of power good signal is generally 5V.

When the booting of BIOS starts it first do the POST (power on self test) which checks the devices that is connected and if there is an error it makes notification in the form of BEEP (A sound of indication ).

The BIOS then looks for other devices like ROM to see if any of them have BIOSes. Normally, the IDE/ATA hard disk BIOS will be found at C8000H and executed. If any other is associated have BIOS, they are executed as well.

Then the BIOS display the welcome screen. Which is nothing but the drawing which is displayed over the screen and the selected OS is chosen by reading the ASCII values of the up down arrow key.

The selected OS is then start its own MBR and the OS comes into the main memory.

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SUBJECT WISE ANALYSIS FOR GATE EXAMINATION (FOR CS, IT AND MCA SYLLABUS) FROM 2006 TO 2011

SECTION WISE RELEVANCE

Hello readers here i am going to provide you a SUBJECT WISE ANALYSIS FOR GATE EXAMINATION which will give you a summary of the number of questions which had been asked in GATE exam in last six years from different subjects. 

Here is the TABLE

GATE      2006                           2007                           2008

Section	Marks	Percentage	Marks	Percentage	Marks	Percentage
Engineering  Mathematics	29	19.33	27	18	27	18
Digital Logic	13	8.67	13	8.67	6	4
Computer  organization	11	7.33	13	8.67	22	14.67
Theory of computation	14	9.33	12	8	15	10
Data structure and algorithms	29	9.33	33	22	39	26
Compiler design	13	8.67	11	7.33	6	4
Operating Systems	21	14	15	10	13	8.67
Dbms	9	6	12	8	12	8
Computer Networks	11	7.33	14	9.33	10	6.67
Software engineering and Web technology

 

GATE         2009                                        2010                                       2011

Section	Marks	Percentage	Marks	Percentage	Marks	Percentage
Engineering  Mathematics	16	16	19	19	19	19
Digital Logic	5	5	8	8	7	7
Computer  organization	5	5	8	8	10	10
Theory of computation	9	9	7	7	9	9
Data structure and algorithms	21	21	13	13	11	11
Compiler design	2	2	3	3	3	3
Operating Systems	16	16	7	7	7	7
Dbms	10	10	7	7	7	7
Computer Networks	10	10	7	7	6	6
Software engineering and Web technology	6	6	6	6	6	6
General ability			15	15	15	15

From these TABLES we can find that Engineering Mathematics and DS and Algorithms take almost 30-40 percent of marks so you should not leave these subjects and part general ability contains 15% so this is going to be very helpful for scoring marks.

SO again take a look to these TABLES and start preparing this is going to very helpful for you.. 

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