课程名称︰计算机概论 课程性质︰选修 课程教师︰周承复 开课学院：电机资讯学院 开课系所︰资工系 考试日期（年月日）︰2012.11.5 考试时限（分钟）：100分钟 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : 1. (20%) Data Compression a) (5%) Encode the following characters using Huffman coding with the given frequencies : A(15),B(5),C(10),D(20),E(25),F(17),G(8) b) (15%) Encode the message BACABBBCABAA using the Lempel Ziv method, then decode the encoded message to get the original message. 2. (45%) Number System a) (5%) What is the binary representation of 7 9/16 ? b) (10%) Using an 8-bit allocation, first convert each of the following integers to two's complement, do the operation, and then convert the result to decimal. (1) 12 + 43 (2) 15 - 60 c) (10%) What bit pattern (and its value) represents the sum of 11101011 and 01000111 if the patterns represent values stored in two's complement notation? What if the patterns represent values stored in the floating-point format discussed in Chapter 1 ? d) (5%) How many errors in a single code pattern could be corrected when using an error-correcting code in ehich each code pattern is a Hamming distance of at least five from any other code pattern ? e) Identify both the mask and the logical operation needed to accomplish each of the following objectives : (i) (5%) Put 1s in the upper 4 bits of an 8-bit pattern without disturbing the other bits. (ii) (5%) Complement the lower 4 bits of an 8-bits pattern without changing the other bits. f) (5%) What is difference between logical shift and arithmetic shift ? 3. (20%) Networking a) What is CSMA/CD ? b) Please explain why CSMA/CD is not compatible (feasible) with wireless networks. (e.g., wifi network) 4. (10%) Operation System Suppose each non-sharable resourse in a computer system is classified into as a level 1, level 2, or level 3 resource. Moreover, suppose each process in the system is required to request the resources it needs according to the required level 1 resource at once before requesting any level 2 resources. Once it receives the level 1 resources, it can request all the required level 2 resources, and so on. Can deadlock occur in such a system? Why or why not ? 5. (15%) The following table shows a portion of a machine's memory containing a program written in the language described in the language description table. Answer the questions below assuming that the machine is started with its program counter containing 00. address content address content 00 10 07 00 01 02 08 C0 02 24 09 00 03 04 0A C0 04 B4 0B 00 05 0A 0C C0 06 C0 0D 00 a) What bit pattern will be in register 0 when the machine halts ? b) What bit pattern will be in register 4 when the machine halts ? c) What bit pattern will be in the program counter when the machine halts ? 6. (10%) a) (6%) "360p" low definition video can be delivered at a rate of 24 frames per second (fps) where each frame has a resolution of 640 x 360 pixels using 24 bits per pixel. Can an uncompressed video stream of this format be sent over a USB 1.1 serial port? USB 2.0 serial port ? USB 3.0 serial port ? Explain. (Note : The maximum speed of USB 1.1, USB 2.0, USB 3.0 serial ports are 12Mbps, 480Mbps, and 5Gbps respectively.) b) (4%) Where is the CPU cache placed between ? (choose from moniter, register, hard disk. CD-ROM, main memory, and I/O controller) 7. (10%) Please use only NAND gates to construct a XOR gate. 8. (10%) Suppose a computer contained 512MB of main memory, and an operating system needed to create virtual memory of twice that size using pages of 8KB. How many pages would be required ? --

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