CDAC Placement Paper on 6 June 2013

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    TYPICAL QUESTIONS & ANSWERS PART – I OBJECTIVE TYPE QUESTIONS
    Each Question carries 2 marks.


    Choose the correct or best alternative in the following:


    Q.1 If the crystal oscillator is operating at 15 MHz, the PCLK output of 8284 is


    (A)2.5 MHz.
    (B)5 MHz.
    (C)7.5 MHz.
    (D)10 MHz.


    Ans:(A)

    Q.2In which T-state does the CPU sends the address to memory or I/O and the ALE signalfor demultiplexing


    (A)T1.
    (B)T2.
    (C)T3.
    (D)T4.


    Ans During the first clocking period in a bus cycle,which is called T1, the address of the memory or I/O location is sent out and the control signals ALE, DT/R’ and IO/M’are also output. Hence answer is (A).

    Q.3 If a1M1× DRAM requires 4 ms for a refresh and has 256 rows to be refreshed, no more than __________ of time must pass before another row is refreshed.


    (A)64 ms.
    (B)4 ns.
    (C)0.5 ns.
    (D)15.625

    Answer is (B)

    Q.4 In a DMA write operation the data is transferred
    (A)from I/O to memory.
    (B)from memory to I/O.
    (C)from memory to memory.
    (D)from I/O to I/O.


    Ans A DMA writes operation transfers data from an I/Odevice to memory. Hence answer is (A).

    Q.5 Which type of JMP instruction assembles if the distance is 0020 h bytes
    (A)near.
    (B)far.
    (C)short.
    (D)none of the above.


    AnsThe three byte near jump allows a branch or jump within ± 32K bytes. Hence answer is (A).

    Q.6A certain SRAM has 0CS=,0WE=and1OE=. In which of the followingmodes this SRAM is operating
    (A)Read
    (B)Write
    (C)Stand by
    (D)None of the above


    Ans For CS’=WE’=0, write operation. Hence answer is (B)
    .
    Q.7 Which of the following is true with respect to EE PROM?
    (A)contents can be erased byte wise only.
    (B)contents of full memory can be erased together.
    (C)contents can be erased using ultra violet rays
    (D)contents can not be erased


    Answer is (C).

    Q.8Pseudo instructions are basically
    (A)false instructions.
    (B)instructions that are ignored by the microprocessor.
    (C)assembler directives.
    (D)instructions that are treated like comments.


    Pseudo-instructions are commands to the assembler.All pseudo-operations start with a period. Pseudo-instructions are composed of a pseudo-operation which may befollowed by one or more expressions. Hence answer is (C).

    Q.9 Number of the times the instruction sequence below will loop before coming out of loop is MOV AL, 00hA1: INC AL JNZ A1


    (A)00
    (B)01
    (C)255
    (D)256


    Ans
    Answer is (D)

    Q.10 What will be the contents of register AL after the following has been executed MOV BL, 8C MOV AL, 7E ADD AL, BL


    (A)0A and carry flag is set
    (B)0A and carry flag is reset
    (C)6A and carry flag is set
    (D)6A and carry flag is reset


    Ans , Result is 1,0A. Hence answer is (A).

    Q.11Direction flag is used with
    (A)String instructions.
    (B)Stack instructions.
    (C)Arithmetic instructions.
    (D)Branch instructions.


    Ans The direction flag is used only with the string in structions. Hence answer is (A).

    Q.12Ready pin of a microprocessor is used
    (A)to indicate that the microprocessor is ready to receive inputs.
    (B)to indicate that the microprocessor is ready to receive outputs.
    (C)to introduce wait states.(D)
    to provide direct memory access.


    Ans
    This input is controlled to insert wait states into the timing of the microprocessor.Hence answer is (C).

    Q.13 These are two ways in which a microprocessor can come out of Halt state.
    (A)When hold line is a logical 1.
    (B)When interrupt occurs and the interrupt system has been enabled.
    (C)When both (A) and (B) are true.
    (D) When either (A)or (B) are true.


    Ans
    Answer is (A)

    Q.14In the instruction FADD, F stands for


    (A)Far.
    (B)Floppy.
    (C)Floating.
    (D)File.


    Ans
    Adds two floating point numbers. Hence answer is (C).

    Q.15SD RAM refers to
    (A)Synchronous DRAM
    (B)Static DRAM
    (C)Semi DRAM
    (D)Second DRAM


    Ans, Answer is (A)

    Q.16 In case of DVD, the speed is referred in terms of n X (for example 32 X). Here, Xrefers to


    (A)150 KB/s
    (B)300 KB/s
    (C)1.38 MB/s
    (D)2.4 MB/s


    Ans
    Answer is (C).

    Q.17Itanium processor of Intel is a
    (A)32 bit microprocessor.
    (B)64 bit microprocessor.
    (C)128 bit microprocessor.
    (D)256 bit microprocessor.


    Ans
    The Itanium is a 64-bit architecture microprocessor. Hence answer is (B).

    Q.18 LOCK prefix is used most often
    (A)during normal execution.
    (B)during DMA accesses
    (C)during interrupt servicing.
    (D)during memory accesses.


    Ans LOCK is a prefix which is used to make an instruction of 8086 non-interruptable.Hence answer is (C).

    Q.19The Pentium microprocessor has______execution units.


    (A)1
    (B)2
    (C)3
    (D)4


    Ans The Pentium microprocessor is organized with three execution units. One executes floating-point instructions, and the other two (U-pipe and V-pipe) execute Hence answer is (C).

    Q.20EPROM is generally erased by using


    (A)Ultraviolet rays
    (B)infrared rays
    (C)12 V electrical pulse
    (D)24 V electrical pulse


    AnsThe EPROM is erasable if exposed to high-intensity ultraviolet light for about 20 minutes or less. Hence answer is (A)

    Q.21 Signal voltage ranges for a logic high and for a logic low in RS-232C standard are
    (A)Low = 0 volt to 1.8 volt, high = 2.0 volt to 5 volt
    (B)Low =-15 volt to –3 vol, high = +3 volt to +15 volt
    (D)Low = +3 volt to +15 volt, high = -3 volt to -15 volt
    (E)Low = 2 volt to 5.0 volt, high = 0 volt to 1.8 volt


    Ans Answer is (B)

    Q.22The PCI bus is the important bus found in all the new Pentium systems because


    (A)It has plug and play characteristics
    (B)It has ability to function with a 64 bit data bus
    (C)Any Microprocessor can be interfaced to it with PCIcontroller or bridge
    (D)All of the above


    Ans, Answer is (D).

    Q.23 Which of the following statement is true?
    (A)The group of machine cycle is called a state.
    (B)A machine cycle consists of one or more instructioncycle.
    (C)An instruction cycle is made up of machine cycles a nd a machine cycle ismade up of number of states.
    (D)None of the above


    Ans An instruction cycle consists of several machine cycles. Hence Answer is (B).




    Q.24 8251 is a
    (A)UART
    (B)USART
    (C)Programmable Interrupt controller
    (D)Programmable interval timer/counter



    Ans The Intel 8251 is a programmable communication interface. It is USART.

    Q.25 8088 microprocessor has
    (A)16 bit data bus
    (B)4 byte pre-fetch queue
    (C)6 byte pre-fetch queue
    (D)16 bit address bus


    Ans
    The 8088 is a 16-bit microprocessor with an 8-bitdata bus. The 16-bit addressbus. Hence answer is (D)

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