1. What is the definition of multimedia?

Concurrent presentations of multiple formats of media

2. What are the two major areas of multimedia?

Computer Graphics
Computer Audio

3. What is the definition of Computer Graphics?

Creation, storage and manipulation of models and images

4. A certain animal can recognize up to 250000 colors. How many bits do we need to represent all colors this animal can recognize? Illustrate your steps.

Soln 1 (guessing)

# of binary numbers represented = 2 ^ (# of bits)

2^17 = 131072 < 250000
2^18 = 262144 > 250000

So, 18 bits is required.

Soln 2 (using log - 2 as the base)

log 250000 = 17.931568569324174087221916576936

So, 18 bits is required.

5. What's is the color model for TV color system?

YIQ

6. How many primary colors are there in the RGB color model? What are these colors?

3. Red, green, blue

7. In a particular RGB color model, x bits are used to store the amount of each primary color. What is the total number of colors in this model? Express the answer in terms of x.

total # of bits used to represent colors = 3x

Since

# of binary numbers represented = 2 ^ (# of bits)

So,

total # of colors in this model = 2^(3x)

8. The resolution of a monitor is l*w pixel. The color depth is b bits. Calculate the amount of video memory required. Illustrate your steps and express your answer in the unit MB.

Amount of video memory required = Color Depth * resolution
= b bit * (l*w)
= b*l*w bit
= b*l*w/8 byte
= b*l*w/(8*1024) Kbyte
= b*l*w/(8*1024*1024) Mbyte

9. If the sampling rate of an audio recording device is x kHz.

How many samples does it take in t seconds?

sampling rate = # of samples taken / time

# of samples = sampling rate * time
= x kHz * t sec
= x * 1024 * 1/sec * t * 1 sec
= x * t * 1024
= 1024tx

To take y samples, how many seconds does it take? (given that sampling rate = (no. of samples taken)/(1 unit of time))

sample rate = # of samples taken / time
# of samples = sampling rate * time
time = # of samples / sampling rate
= y / (x * 1024)
= y/(1024x )

10. Given that

Size of an audio file (bit) = sampling rate (Hz) * bit depth * recording duration (sec)

If the sampling rate is x Hz, bit depth is b bits and the recording duration is s seconds, calculate the size of the audio file in the unit of MB? Illustrate your steps.

size = x Hz * b bit * s sec
= x * 1/sec * b bit * s sec
= x * b * s bit
=(x * b * s)/8 bytes
=(x * b * s)/(8 * 1024) KBytes
=(x * b * s)/(8 * 1024 * 1024) MBytes

OS

11. What's the definition of multiprogramming?

concurrent execution of more than 1 programs

12. What are the two things that an OS do for memory management?

keep track on which portion of memory is in use and by which process
allocate memory to a process and free memory from a process

13. Can a directory contain no file or subdirectory? If yes, how is it called?

Yes. It is called an empty directory.

14. What are the two most basic form of identity in UNIX?

user account
group membership

15. The permission setting of file is -rwxr-x--x. Is it a read only file for

the owning user?

no. because it can both read and write

the owning group?

yes. because only read access is allowed

others?

no. because read access is not allowed

16. Formulate the permission setting for the followings cases. If the right on a particular access is not specified, assume that access is forbidden.

a. a file which is readable and writable to the owning user, executable to the owning group

-rw---x---

b. a directory that can be read, written by anyone

drw-rw-rw-

c. a file which is readable to the owning user, writable to the owning group and executable to others.

-r---w---x

Research question

Use the skills that you learnt from the information competency class meetings, look for a UNIX command used for changing file access permissions. State the source (eg. book, manual, Internet) where you found this command. Also, briefly explain how to use this command.