SESSION:35

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1)       What are Encoders and Decoders?

Encoders are logic circuits which change a set of signals into a code using certain logic. It has a set of input signals of which only one line is active at a certain instant of time.

Decoders are logic circuits which accept a set of inputs that represent a binary number and activate only the output that corresponds to the input number. It produces only one output as high for an input set.

Encoding and Decoding is done for the safe transmission of data.
Now a day, data is encrypted using 128-bit encryption. It may have 2 to the power of 128 possible combinations. This is widely regarded as immune to brutal force attacks from hackers simply because it would take too long to crack.

2)       What’s a microprocessor?

A microprocessor is a computer. It’s an IC (integrated circuit), and acts as the central computing/processing unit of any system. It works on the input in the way required by the user, as he programs it (the program is stored in the memory of the processor), and gives the output/result one is looking for. 

Initially, computers were designed with a large number of transistors soldered on the circuit board with lots of visible logic gates. Basically, it was too big and hence, the signals had to travel long distances resulting overheating, and largely restricted the speed of the computer. The new and small IC, act as microprocessors and help the computer to process at speeds greater by far!

The first few microprocessors were calculators, and they came out in 1970s.

For example: INTEL4004, TMS 1000 etc.

3)       Briefly explain the construction and application of a JFET.

JFET stands for Junction Field Effect transistor. This device uses one electrical field signal to control another. Electrical fields varying in one region is used to control current flow between two other terminals.

Some of the applications of JFET are:

Solving Analog Problems: It is used in solving real-world, small-signal-chain problems typically requiring low power, high impedance and low noise.

Military applications: They also offer excellent radiation and temperature tolerance, required in many military applications.

Advantages of JFET are:

·         It is a voltage controlled device, not current controlled.

·         It shows a high degree of isolation between input and output signals.

·         It is a unipolar device. Hence, the charge carriers are either only electrons or only holes.

·         It makes less noise compared to other devices.

4)       What are the flags in 8086?

In 8086 Carry flag, Parity flag, Auxiliary carry flag, Zero flag, Overflow flag, Trace flag, Interrupt flag, Direction flag, and Sign flag.

5)       Why crystal is a preferred clock source?

Because of high stability, large Q (Quality Factor) & the frequency that doesn’t drift with aging. Crystal is used as a clock source most of the times.

6)       In 8085 which is called as High order / Low order Register?

Flag is called as Low order register & Accumulator is called as High order Register.

7)       What is Tri-state logic?

Three Logic Levels are used and they are High, Low, High impedance state. The high and low are normal logic levels & high impedance state is electrical open circuit conditions. Tri-state logic has a third line called enable line.

8)       What happens when HLT instruction is executed in processor?

The Micro Processor enters into Halt-State and the buses are tri-stated.

9)       Which Stack is used in 8085?

LIFO (Last In First Out) stack is used in 8085.In this type of Stack the last stored information can be retrieved first.

10)    What is Program counter?

Program counter holds the address of either the first byte of the next instruction to be fetched for execution or the address of the next byte of a multi byte instruction, which has not been completely fetched. In both the cases it gets incremented automatically one by one as the instruction bytes get fetched. Also Program register keeps the address of the next instruction.

11)    What are the various registers in 8085?

Accumulator register, Temporary register, Instruction register, Stack Pointer, Program Counter are the various registers in 8085.

12)    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.

13)    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.

14)    How many bit combinations are there in a byte?

Byte contains 8 combinations of bits.

15)    Have you studied buses? What types?

There are three types of buses.

Address bus: This is used to carry the Address to the memory to fetch either Instruction or Data.

Data bus: This is used to carry the Data from the memory.

Control bus: This is used to carry the Control signals like RD/WR, Select etc.