Mid-Term Exam
Introduction to Computer Science
NCNU CSIE

Date: October 29th, 2008
Time: 14:10-17:00

(20%) What do the following acronyms stand for?

1. ALU
2. ASCII
3. CPU
4. EEPROM
   
5. IEEE
   
6. DRAM
7. CD-R
   
8. CD-ROM
9. SCSI
10. USB

(10%) If the ASCII code for 'N' is 01001110, then the ASCII code for 'n' is _____________.

(10%) Suppose "even parity" is used when we store the lowercase character 'n' in ASCII code on a tape.  What will be the value of the parity bit?


(10%) CD-ROM uses the infrared laser, while the new blue-ray DVD uses the blue laser in reading and writing.  According to your knowledge in physics, is the wavelength of the blue laser longer or shorter than the infrared laser?


(10%) How are data erased on a CD-RW?

(10%) Suppose you are using a 56Kbps (bit per second) modem to download a file whose size is 28MBytes, can you finish the download process in an hour? Show us your calculation about at least how many minutes will be required.

(10%) Using 8-bit allocation, interpret 10001000 if the number was stored as

1. unsigned integer
2. sign-and-magnitude
3. one's complement
4. two's complement
5. Excess_127

(10%) The software used to write a program is called a _____________.

1. preprocessor
2. text editor
3. translator
4. source file

(10%) Using a 4-bit allocation, perform the following operations for two's complement binary numbers. (Note: Report the results in both binary and decimal representations, and indicate "overflow" in case it occurs.)

1. 0011 + 0011
2. 0111 + 0111
3. 1001 + 1001
4. 1111 + 0111
5. 1000 + 0111

(10%) In contrast to a binary numbering system which has only two digits 0 and 1, a "septenary" system has only seven digits 0, 1, 2, 3, 4, 5, 6. In this system, 10₇ = 7₁₀, and 11₇ = 8₁₀. Perform the following operations in septenary systems and write down the result (also in septenary systems).

1. 13₇ + 24₇
2. 56₇ + 56₇
3. 11₇ * 11₇
4. 13₇ * 13₇
5. 25₇ * 25₇