专业： 班级： 学号： 姓名： -装-订-线- - -南京师范大学2008-2009学年 第2学期 电气与自动化工程 学院 中英班 专业 2007 年级数字电子技术基础（Electronics)课程期终试卷B Name： Class： Student ID： Score： No.123456789Points得分1. Choose the correct answer:（26 points）(1) An open TTL NOR gate input (a) acts as a LOW (b) acts as a HIGH (c) should be connected to VCC (d) cant be determined(2) Most devices are interfaced to a bus with (a) totem-pole outputs (b) tri-state drivers (c) PNP transistors (d) resistors(3) The output of an AND gate with inputs A, B, and C is a 1 (HIGH) when (a) A = 1, B = 1, C = 1 (b) A = 0, B = 0, C = 1 (c) A = 0, B = 1, C = 1 (d) A = 0, B = 0, C = 0(4) According to DeMorgans theorems, the following equality is correct: (a) (b) (c) (d) all of these(5) All Boolean expressions can be implemented with (a) NAND gates only (b) NOR gates only (c) combinations of AND gates, OR gates, and inverters (d) any of these(6) The inputs to a full-adder are A = 1, B = 1 and Cin = 0. The outputs are (a) Sum = 1, Cout = 1 (b) Sum = 1, Cout = 0 (c) Sum = 0, Cout = 1 (d) Sum = 0, Cout = 0(7) The device used to convert a binary number to a 7-segment display format is (a) multiplexer (b) encoder (c) decoder (d) register(8) An example of a data storage device is (a) the logic gate (b) the flip-flop (c) the register (d) both answers (b) and (c)(9) A modulus-12 counter must have (a) 12 flip-flops (b)3 flip-flops (c) 4 flip-flops (d)synchronous clocking(10) A 4-bit binary up/down counter is in the binary state of zero. The next state in the DOWN mode is (a) 0001 (b) 1111 (c) 1000 (d) 1110(11) A ROM is a (a) nonvolatile memory (b) volatile memory (c) read/write memory (d) byte-organized memory(12) A memory with 256 addresses has (a) 256 address lines (b) 6 address lines (c) 1 address lines (d) 8 address lines(13) An 8-bit DAC has a resolution of (a) 0.1% (b) 0.392% (c) 1% (d) 3.92%Points2. Simplify the following expressions as much as possible.（10 points）(1) (2) 得分3. Determine the output of an exclusive-OR gate for the inputs shown below and draw the timing diagram.（5 points）YA BA B Y得分4. A logic circuit accepts a 3-bit word (I2, I1, I0) and provides a 2-bit output (N1, N0) which is a count of the number of bits which are 1 in the input word. Design a circuit to implement this function.（15 points） (1) Develop the truth table and get the SOP expression.(2) Implement the circuit using a 74138 decoder. (You may add extra gates).A0 Y0A1 Y1A2 Y274LS138 Y3 Y4STA Y5STB Y6STC Y7(3) Implement the circuit using a 74153 multiplexer. A1A01D01D11D21D32D02D12D22D31Y2Y741532ST1ST得分 6. Design a modulu-12 counter using a 74161 IC. (8 points)D0LDD1D2D3Q0Q1Q2Q3CEPETCPRD74161得分5. For a negative edge-triggered JK flip-flop with the inputs shown below, develop the Q output waveform relative to the clock. Assume that Q is initially LOW.（10 points）JKQCLRJCPQKPRECPJKKQ得分 7. Draw the state diagram of the following counter.（8 points） CP1CP0Q0Q1Q2Q37490R02R01S92S91CP得分8. Create an astable multivibrator using a 555 timer. The output frequency is 20 kHz. If the external capacitor C is 0.002F and the duty cycle is 75%, determine the values of the external resistors. （10 points） 得分 9. The pin diagram of 74LS00 are given below. Construct the circuit to implement the logic function using a single 74LS00 IC. (8 points) Data Sheet: 74138InputsOutputsS1A2A1A0111111111011111111000000000000