私立中原大學八十八學年度研究所招生考試命題紙

所組別 : 電子工程學系乙組 科目 :數位電路 考試時間 : 05月01日第2節


  1. (20%)Simplify the following Boolean expression in minimal sum-of-products (MSOP) form.

    2.
  2. (20%)Simplify the following Boolean expression in minimal product-of-sums (MPOS) form.

    3.
  3. (30%)A clock-mode digital system called a start-signal generator is to be designed having two input lines, ready and go ,and one output line, z. The output is to remain 0 until the following sequence of events takes place. First, ready must go to 1 for an unspecified number of clock periods. Following this the output, z,will go to 1 for exactly one clock period as soon as go goes to 1. It may be assumed that ready and go will never be 1 simultaneously, and they only change value just after the falling edge of a clock pulse. Once a one-period output has occurred, ready must appear before another one-period output can be generated.

    4. (1)(5%) Please give a typical timing diagram for the system.

    (2)(5%) Let us include only one D flip-lop in the circuit, and label this flip-flop Y. Please give the next-value table Y v+1for the system.

    (3)(5%) Please obtain a minimal sum-of-products input logic for the D flip-flop from the above table.

    (4)(5%) Please give a tabulation of output values as a function of the input and flip-flop values.

    (5)(5%) Please obtain a minimal sum-of-products expression for the output z from the above table.

    (6)(5%) Please give a circuit realization for the system.

  4. (30%) Suppose the word length of a computer is 16 bits and the instruction format is as following.

    5.        The AM section of the instruction (bits 5-7) specifies the addressing mode, which determines how the 8 address bits (8-15) are used. There are five addressing modes for the computer as shown below.

    We will investigate the effect of the different addressing mode on the instruction shown in the following memory.

            The instruction in addresses 250 and 251 is "move to AC" with the address field equal to 500. The program counter PC has the number 250 for fetching this instruction. The accumulator register AC will receive the operand after the instruction is executed. The opcode assigned to MOVE is (00101)2. Assume the index register IX has a value of 100 now.

            In the following table, please list the decimal value of the effective address and the operand to be loaded into the AC for different binary instructions in address 250.

    InstructionEffective AddressOperand
    (00101000)2　　
    (00101001)2　　
    (00101010)2　　
    (00101011)2　　
    (00101100)2　　

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