19-07-2020

Hi,

So, on the 10th of July I put myself a goal to complete DLD notes by 14th of July. It is not achieved. From 11th to 18th I managed to binge all 12 seasons of two and half men.

So today, I climbed to the roof of my house where we had a leakage in the tank pipe. Anyhow, it is damaged beyond repair and needs a replacement. :(

Morning there was some issue with my PC disc and got fixed by windows update. Then on I have surfed through ThePrint. Very interesting topics, thoughts and yes it's salient feature of putting forward the facts. Liberals getting divided, china narrative story centers, ECs appointment process, china's funny business in the world dynamics, scientific and political things.

I have an interest in tracking what is happening in politics. So, yes PurePolitics with Shanker Arnimesh is a good listen for me. Explained the 3 plot story in rajasthan going on nicely.  But today what made me write is a discussion by SpeakIn with Prof. Dinesh Singh. He made an interesting interpretation of education: it is a journey within and that we all have a drumbeat of the soul "anthardhwani", the challenge is to find what is your anthardhwani. Finding one is just the first step. And being educated means to walk in harmony with this drumbeat in the real world. The more you march with that the more you discover yourself and the more you discover yourself the more you are educated. He gave examples like srinivasa ramanujan's anthardhwani was mathematics, sachin's was cricket, gandhiji's was the satya(truth). And they pursued this with the exclusion of everything else. 

In times of crisis be brave and let the crisis take it's own course, it will eventually leave. Stay calm, stay focused and with "dheeraj"(bravery) we should acquire the persona of dheer buddhi. "What will change you is what you allow to change you. Nothing else will change you." 

If you have the curiosity and the drive "jigynasa" within you, you can get educated by yourself. The guru is right there sitting on the web "Harnessing the power of web like a guru". You just have to be patient and 

Web is a universe of knowledge. There is good and bad in web just like in the real world. So, we should use our discerning mind "vivekam" to decide what is good for you and what is not. Even when the ocean is churned sagar mathan not all good things came there was poison also. So we have to leave the poison aside and take the good things. Web is a huge resource, so churn it.

First we need to see various things that stimulate you and make your drumbeat speak out. Then you know what it is. Example, gandhi from satya harishchandra, sachin from his watching someone play cricket, ramanujan receiving a foreign mathematician book that inspired him to take up math.

We should be thinkers and learners for life. It is a two way process. Needs and challenges of the world stimulates the mind of a student and they acquire that knowledge which he/she feel is necessary to apply and solve the problem and in this process the student begins to get educated.

This discussion was very revelant and close to my stage of life right now. So, thought why not make a notes of it. 

Good night.

10-07-2020

Evening,

It's 3:53 AM on 11-07-2020, hell yeah!

Good progress today! Completed Digital Logic Completely and also completed notes till Minimization. Will complete Design and Synthesis of CC tomorrow. 

GOAL and DEADLINE is to complete DLD notes by 14-07-2020.

Some interesting points to know about number system before going to bed! 

1.Sign bit extension: (for negative numbers)

In Sign Magnitude form:

Copy the sign to the MSB and copy the number to the bits on LSB and fill in the gap with zeros in middle.

In 1's Complement form:

Copy the MSB to all the remaining bits on the MSB of the result. Reason being when to take the 1's complement to that all become 0's so doesn't effect the value.

In 2's Complement form:

Copy the MSB to all the remaining bits on the MSB of the result. Same as 1's complement but the reason being -2powerN+2power(N-1) = -2power(N-1)

2. Overflow: When result cannot be represented in the register, overflow occurs.

Cin XOR Cout = OF

Or when sum of two postive numbers give a negative sum or when two negative terms sum give a positive lands into OF. (which becomes meaningless).

3. Addition in Excess-3:

If carry occurs -> +3

If carry doesnot occur -> -3

Keep in mind that the number of digits of operands and result should be equal.

4. Gray Code is unit-distant,reflexive,cyclic.

Okay sleep tight! 

09-07-2020

Evening,

Good progress today too! Five hours of Number Systems completed. 

Incidentally, sir released a video to study for longer hours with the pomodore or some technique. Ironically the thing is I ended up watching five episodes of that two and a half men. Now closed the tab to write this!

Hey few things to be noted in number systems is,

The largest number possible to represent using n digits of base b is (b to the power of n) - 1.

Base is also called radix.

Minimum number of digits required to represent a k digit base b number in base x system is (n) >= k(log b to the base x).

Complementary Number system is mainly proposed to do subtraction using addition circuit already present.

Base b has two types of complements: b-1 's complement and b's complement.

So, how the subtraction (X-Y) works using complements is as below:

For b-1 's complement:

If  X-Y>=1, ignore carry and add 1 to the X+Ycomplement

If X-Y<1, get the b-1 's complement of X+Ycomplement and negate the result to get answer in a familiar form.

For b 's complement:

If  X-Y>=0, ignore carry to the X+Ycomplement

If X-Y<0, get the b 's complement of X+Ycomplement and negate the result to get answer in a familiar form.

Binary numbers are of two types Signed and unsigned.

Signed numbers can be represented in three ways:

1. Sign magnitude form
2. Signed 1's complement 
3. Signed 2's complement

Here we are only talking of integers not other numbers like fractions or real numbers(integers+fractions). Generally integers have decimal point fixed after the least significant number as well as fractions at their most significant number. Hence called Fixed Pointer Representation and as you have gussed the other (integers+fractions or real numbers) have floating point representation since the decimal point/radix point is not fixed. (LOL floating!)

Signing off for today! Good night.

08-07-2020

Hola!

Good progress today, completed yesterday's last hours content and also covered three hours of Sequential Circuits. Will complete another hour also. 

GOAL and DEADLINE is that should complete Number Systems by 10-07-2020 and start notes for DLD. 

As we have seen SR yesterday i.e. Set-Reset FlipFlop, another type is JK FlipFlop which acts same as SR but is also define when JK=11 also unlike SR=11 is invalid JK=11 gives complement of Qpresent. 

JK is again can be modified or seen as two broad types -> T(toggle) and D(delay) FlipFlops. These have an extensive application and role in the construction of counters.

Solve any question by tabling or constructing as follows:

Characteristic Equation -> Function Table-> Characteristic Table-> Excitation Table.

Another important concept is the conversion of a given FF to another FF:

Suppose,

AB is a given/existing/to be used to realize another FF and 

CD is the target FF/new FF/to be constructed using given FF then,

CD should be realized using inputs of given FF AB.

Steps: (Here important thing is to know what is the FF to be constructed using what FF!)

1. Get the characteristic table of the target FF

2. Replace the next state using excitation of the given FF

3. Obtain the expression for the input of given FF and realize them.

Counters are used to provide accurate timing and control signals. Two types: synchronous and asynchronous.

For N states in a state diagram - > Ceil(logN) FFs are needed to realize it.

All the free running counters are Self-starting counters.

Synchronous:

In IC fabrication D-FFs are used. Technically, any flipflop can be used.

Also called shift counters.

Two types: Ring counter I0 = f(QN-1) and Johnson counter I0=f(QN-1 prime).

Johnson counter is also called as switch-tail ring counter. Can be used as gray counter since only one bit changes for every adjacent transition state in the state diagram.

Asynchronous:

In IC fabrication T-FFs are used. Technically, any flipflop can be used.

Also called ripple counters. 

IC-7490 -> decade counter(%10 counter) and IC-7492 -> Hexadecimal counter(%16 counter)

binary-up counter (increasing order states) can be designed.

Hope it is not too technical but it is very important to know how these flipflops work since they are the basic building blocks of memory as well as some control systems like if OS wants to assign a resource through round-robin, then using counters we can make sure that each device is getting the resource for an equal amount of time. Okay! that's it for today.

 

Sayonara!!

07-07-2020

Good Evening,

Completed two hours today with which Design and synthesis of Combinational circuits is completed. 

Now moving on with Sequential circuits. It is 00:12 now and completed almost a hour of that now. SRFlip Flop.

FlipFlop is the smallest building block of memory. It can store a bit of data. Has two stable states 0 or 1 and hence can also be called as "bistate multi-vibrator".

Though it may have the state complement also stored i.e. Q and Qprime it does not mean it can store 2 bits bcoz 11 and 00 cannot be stored. Simple!

Now one of the types is this SR Flip Flop. Mostly SR input is given through a NAND gate (popular representation). 

FlipFlop Circuit - S R have NAND gate before giving it to the inputs of latch.

Characteristic Table - SRQ |||||| 00 Latch ||||||||| 01 Reset |||||||||||| 10 Set ||||||||||| 11 Invalid

Characteristic Equation - Which is used for realization or implemetation -> Qnext = S+Qpresent.Rprime

Excitation Table - What inputs/excitations (SR) should be given for the behavior of Qpresent -> Qnext transition. 

Function Table - Writing the Qnext in terms of Qpresent based on the inputs S and R.

So basically, these are the things we should understand to analyze a flipflop. 

Anyways, I will try to complete another hour today and try to complete notes first man. It's been piling up for a while now. :(

Good night.

05-07-2020

Good Evening,

It is 21.00 now. Completed two hours of videos. Now moving on to Encoders (Non-priority). 

ok. Done with three hours now.

04-07-2020

Good Evening,

I have completed two hours of video today.