Description : A dynamic RAM has refresh cycle of 32 times per msec. Each refresh operation requires 100 nsec and a memory cycle requires 250 nsec. What percentage of memory’s total operating time is required for refreshes? (A) 0.64 (B) 0.96 (C) 2.00 (D) 0.32
Last Answer : Answer: D Explanation: in 1ms : refresh = 32 times Memory cycle = 1ms/250ns = 106ns/250ns = 4000 times Therefore, % of refresh time = (32 x 100ns)/(4000 x 250ns) = 3200ns/1000000 x 100% = 0.32%
Description : In digital ICs, Schottky transistors are preferred over normal transistors because of their (A) Lower Propagation delay. (B) Higher Propagation delay. (C) Lower Power dissipation. (D) Higher Power dissipation.
Last Answer : Ans: A Lower propagation delay as shottky transistors reduce the storage time delay by preventing the transistor from going deep into saturation.
Description : The information in ROM is stored (A) By the user any number of times. (B) By the manufacturer during fabrication of the device. (C) By the user using ultraviolet light. (D) By the user once and only once.
Last Answer : (B) By the manufacturer during fabrication of the device.
Description : Which of following can not be accessed randomly (A) DRAM. (B) SRAM. (C) ROM. (D) Magnetic tape.
Last Answer : Ans: D Magnetic tape can only be accessed sequentially.
Description : Which of following requires refreshing? (A) SRAM. (B) DRAM. (C) ROM. (D) EPROM.
Last Answer : (B) DRAM
Description : The process of entering data into a ROM is called (A) burning in the ROM (B) programming the ROM (C) changing the ROM (D) charging the ROM
Last Answer : Ans: B The process of entering data into ROM is known as programming the ROM.
Description : Which of the memory is volatile memory (A) ROM (B) RAM (C) PROM (D) EEPROM
Last Answer : Ans: B RAM is a volatile memory (Volatile memory means the contents of the RAM get erased as soon as the power goes off.)
Description : The ram which is created using bipolar transistors is called: a. Dynamic RAM b. Static RAM c. Permanent RAM d. DDR RAM
Last Answer : b. Static RAM
Description : A certain population of ALOHA users manages to generate 70 request/sec. If the time is slotted in units of 50 msec, then channel load would be a. 4.25 b. 3.5 c. 350 d. 450
Last Answer : b. 3.5
Description : In a time multiplexed space switching system, one speech sample appears every (A) 125 micro sec (B) 20 msec (C) 125 msec (D) 1 sec
Last Answer : (A) 125 micro sec
Description : A disk drive has 100 cylinders, numbered 0 to 99. Disk requests come to the disk driver for cyclinders 12, 26, 24, 4, 42, 8 and 50 in that order. The driver is currently serving a request at cyclinder 24. A seek takes ... (SSTF) algorithm? (A) 0.984 sec (B) 0.396 sec (C) 0.738 sec (D) 0.42 sec
Last Answer : C
Description : A weighted resistor digital to analog converter using N bits requires a total of (A) N precision resistors. (B) 2N precision resistors. (C) N + 1 precision resistors. (D) N – 1 precision resistors.
Last Answer : (A) N precision resistors.
Description : The output of a JK flipflop with asynchronous preset and clear inputs is 1'. The output can be changed to 0' with one of the following conditions. (A) By applying J = 0, K = 0 and using a clock. (B) ... (C) By applying J = 1, K = 1 and using the clock. (D) By applying a synchronous preset input.
Last Answer : Ans: C Preset state of JK Flip-Flop =1 With J=1 K=1 and the clock next state will be complement of the present state.
Description : 1’s complement representation of decimal number of -17 by using 8 bit representation is (A) 1110 1110 (B) 1101 1101 (C) 1100 1100 (D) 0001 0001
Last Answer : (A) 1110 1110
Description : Data can be changed from special code to temporal code by using (A) Shift registers (B) counters (C) Combinational circuits (D) A/D converters.
Last Answer : Ans: A Data can be changed from special code to temporal code by using Shift Registers. (A Register in which data gets shifted towards left or right when clock pulses are applied is known as a Shift Register.)
Description : What is the phase delay of an 800 Hz voice signal if the phase shift is 15 degrees? A. 1.25 µsec B. 52 µsec C. 83.33 µsec D. 26 µsec
Last Answer : B. 52 µsec
Description : For a light detector, responsivity is measured in: a. amps per watt b. µW per amp c. mA per joule d. µsec per µW
Last Answer : a. amps per watt
Description : A 3 -stage ripple counter has Flip Flop with propagation delay of 25 nsec and pulse width of strobe input 10 nsec. Then the maximum operating frequency at which counter operates reliably is
Last Answer : A 3 -stage ripple counter has Flip Flop with propagation delay of 25 nsec and pulse width of strobe input 10 nsec. Then the maximum operating frequency at which counter operates reliably is 12.67 MHz
Description : A 4-bit synchronous counter uses flip-flops with propagation delay times of 15 ns each. The maximum possible time required for change of state will be (A) 15 ns. (B) 30 ns. (C) 45 ns. (D) 60 ns.
Last Answer : Ans: A 15 ns because in synchronous counter all the flip-flops change state at the same time.
Description : The A/D converter whose conversion time is independent of the number of bits is (A) Dual slope (B) Counter type (C) Parallel conversion (D) Successive approximation.
Last Answer : Ans: C The A/D converter whose conversion time is independent of the Number of bits is Parallel conversion. (This type uses an array of comparators connected in parallel and comparators compare the input voltage at a particular ratio of the reference voltage).
Description : The digital logic family which has the lowest propagation delay time is (A) ECL (B) TTL (C) CMOS (D) PMOS
Last Answer : Ans: A The digital logic family which has the lowest propagation delay time is ECL (Lowest propagation delay time is possible in ECL because the transistors are used in difference amplifier configuration, in which they are never driven into saturation and thereby the storage time is eliminated).
Description : Define Asynchronous sequential circuit?
Last Answer : In asynchronous sequential circuits change in input signals can affect memory element at any instant of time.
Description : Define synchronous sequential circuit
Last Answer : In synchronous sequential circuits, signals can affect the memory elements only at discrete instant of time.
Description : What are the different types of shift type?
Last Answer : There are five types. They are, Serial In Serial Out Shift Register Serial In Parallel Out Shift Register Parallel In Serial Out Shift Register Parallel In Parallel Out Shift Register Bidirectional Shift Register
Description : Define shift registers.
Last Answer : The binary information in a register can be moved from stage to stage within the register or into or out of the register upon application of clock ... arithmetic and logic operations used in microprocessors. This gives rise to group of registers called shift registers.
Description : Define registers.
Last Answer : A register is a group of flip-flops flip-flop can store one bit information. So an n-bit register has a group of n flip-flops and is capable of storing any binary information/number containing n-bits.
Description : What is a master-slave flip-flop?
Last Answer : A master-slave flip-flop consists of two flip-flops where one circuit serves as a master and the other as a slave.
Description : What is edge-triggered flip-flop?
Last Answer : The problem of race around condition can solved by edge triggering flip flop. The term edge triggering means that the flip-flop changes state either at the positive ... negative edge of the clock pulse and it is sensitive to its inputs only at this transition of the clock.
Description : Define race around condition.
Last Answer : In JK flip-flop output is fed back to the input. Therefore change in the output results change in the input. Due to this in the positive half of the clock pulse if both J and K are high then output toggles continuously. This condition iscalled ‘race around condition’.
Description : What is the operation of T flip-flop?
Last Answer : T flip-flop is also known as Toggle flip-flop. • When T=0 there is no change in the output. • When T=1 the output switch to the complement state (ie) the output toggles.
Description : What is the operation of JK flip-flop?
Last Answer : When K input is low and J input is high the Q output of flip-flop is set. When K input is high and J input is low the Q output of flip-flop is reset. When both the inputs ... are high it is possible to set or reset the flip-flop (ie) the output toggle on the next positive clock edge.
Description : What is the operation of D flip-flop?
Last Answer : In D flip-flop during the occurrence of clock pulse if D=1, the output Q is set and if D=0, the output is reset.
Description : What are the different types of flip-flop?
Last Answer : There are various types of flip flops. Some of them are mentioned below they are, RS flip-flop SR flip-flop D flip-flop JK flip-flop T flip-flop
Description : Define Flip flop.
Last Answer : The basic unit for storage is flip flop. A flip-flop maintains its output state either at 1 or 0 until directed by an input signal to change its state.
Description : What are the classification of sequential circuits?
Last Answer : The sequential circuits are classified on the basis of timing of their signals into two types. They are, 1)Synchronous sequential circuit. 2)Asynchronous sequential circuit.
Description : What do you mean by comparator
Last Answer : A comparator is a special combinational circuit designed primarily to compare the relative magnitude of two binary numbers.
Description : Define multiplexer
Last Answer : Multiplexer is a digital switch. If allows digital information from several sources to be routed onto a single output line.
Description : What is priority Encoder?
Last Answer : A priority encoder is an encoder circuit that includes the priority function. In priority encoder, if 2 or more inputs are equal to 1 at the same time, the input having the highest priority will take precedence.
Description : Define Encoder?
Last Answer : An encoder has 2n input lines and n output lines. In encoder the output lines generate the binary code corresponding to the input value.
Description : What is binary decoder?
Last Answer : A decoder is a combinational circuit that converts binary information from n input lines to a maximum of 2n out puts lines.
Description : Define Decoder
Last Answer : A decoder is a multiple - input multiple output logic circuit that converts coded inputs into coded outputs where the input and output codes are different.
Description : Define Half adder and full adder
Last Answer : The logic circuit that performs the addition of two bits is a half adder. The circuit that performs the addition of three bits is a full adder.
Description : Define combinational logic
Last Answer : When logic gates are connected together to produce a specified output for certain specified combinations of input variables, with no storage involved, the resulting circuit is called combinational logic.
Description : Convert the decimal number 3.375 to binary. 132) A) 0101.1100 B) 0011.1010 C) 0011.0011 D) 0011.01
Last Answer : D) 0011.01
Description : Convert binary 1001 to octal. 131) A) 1018 B) 98 C) 108 D) 118
Last Answer : D) 118
Description : Convert decimal 19 to octal. 130) A) 278 B) 218 C) 238 D) 178
Last Answer : C) 238
Description : The hexadecimal equivalent of decimal 88 is ________. 129) A) 6816 B) 5816 C) 5116 D) 551
Last Answer : B) 5816
Description : Any number with an exponent of one is equal to 128) A) two. B) itself. C) zero. D) on
Last Answer : B) itself.
Description : What is the decimal value of 20? 127) A) 2 B) 0 C) 1 D) 3
Last Answer : C) 1
Description : The binary equivalent of hexadecimal 16 is ________. 126) A) 01110000 B) 1100001 C) 0010011 D) 0001
Last Answer : D) 0001