digital principles and system design two marks

32.What is propagation delay?It is the average transition delay time for the signal to propagate from inputto output when the signals change in value.33.What is Noise margin?It is the limit of a noise voltage, which may be present with out impairing theproper operation of the circuit.34.What is power dissipation?It is the power consumed by the gate, which must be available from thepower supply.35.Why parity checker is needed?Parity checker is required at the receiver side to check whether the expectedparity is equal to the calculated parity or not. If they are not equal then it is foundthat the received data has error.36.What is meant by parity bit?Parity bit is an extra bit included with a binary message to make the numberof 1’s either odd or even. The message, including the parity bit is transmitted andthen checked at the receiving and for errors.37.Why parity generator necessary?Parity generator is essential to generate parity bit in the transmitter.38.What is IC?An integrated circuit is a small silicon semiconductor crystal called a chipcontaining electrical components such as transistors, diodes, resistors andcapacitors. The various components are interconnected inside the chip to form anelectronic circuit.39.What are the needs for binary codes?a. Code is used to represent letters, numbers and punctuation marks.b. Coding is required for maximum efficiency in single transmission.c. Binary codes are the major components in the synthesis (artificialgeneration) of speech and video signals.d. By using error detecting codes, errors generated in signal transmissioncan be detected.e. Codes are used for data compression by which large amounts of data aretransmitted in very short duration of time.40.Mention the different type of binary codes?The various types of binary codes are,f. BCD code (Binary Coded decimal).g. Self-complementing code.h. The excess-3 (X’s-3) code.i. Gray code. j. Binary weighted code.k. Alphanumeric code.l. The ASCII code.m. Extended binary-coded decimal interchange code (EBCDIC).

n. Error-detecting and error-correcting code.o. Hamming code.41.List the advantages and disadvantages of BCD code?The advantages of BCD code area. Any large decimal number can be easily converted into correspondingbinary numberb. A person needs to remember only the binary equivalents of decimalnumber from 0 to 9.c. Conversion from BCD into decimal is also very easy.The disadvantages of BCD code area. The code is least efficient. It requires several symbols to representeven small numbers.b. Binary addition and subtraction can lead to wrong answer.c. Special codes are required for arithmetic operations.d. This is not a self-complementing code.e. Conversion into other coding schemes requires special methods.42.What is meant by self-complementing code?A self-complementing code is the one in which the members of the numbersystem complement on themselves. This requires the following two conditions to besatisfied.a. The complement of the number should be obtained from that numberby replacing 1s with 0s and 0s with 1s.b. The sum of the number and its complement should be equal todecimal 9. Example of a self-complementing code isi. 2-4-2-1 code.ii. Excess-3 code.43.Mention the advantages of ASCII code?The following are the advantages of ASCII codea. There are 2

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=128 possible combinations. Hence, a large number of symbols,alphabets etc.., can be easily represented.b. There is a definite order in which the alphabets, etc.., are assigned to eachcode word.c. The parity bits can be added for error-detection and correction.44.What are the disadvantages of ASCII code?The disadvantages of ASCII code area. The length of the code is larger and hence more bandwidth is requiredfor transmission.b. With more characters and symbols to represent, this is not completelysufficient.45.What is the truth table?A truth table lists all possible combinations of inputs and thecorresponding outputs.46.Define figure of merit?Figure of merits is defined as the product of speed and power. The speedis specified in terms of propagation delay time expressed in nano seconds.Figure of merits=Propagation delay time (ns)*

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