Solution to Midterm Exam for 690--spring 1997.

1. 24 points

a. the answer is D. lossy compression

	MPEG is for video, and GIF is for images, and lossless would
	not create the greatest compression.

b. the answer is B. instances of classes

c. the answer is A. join

	restrict and project can both be used in non-relational (flat)
	databases.

d. the answer is D. all of the above

2. 25 points

a. The devices should be listed in the following order:

	CPU
	RAM
	Hard Disk
	WAN

b. Cache memory would be placed between the CPU and the RAM and Network
Cache should be connected from WAN to the Hard disk, the RAM, or the
CPU.

	CPU            |-----------CPU
	    \	       |  |--------RAM
	     \	       |  |	   Hard Disk----------|
	     /	       |  |			      | 	
            /	       |  |			      |(best answer)
       	RAM 	       |-----------WAN----------------|

c. WAN: Delivers web page to the computer system.
   Hard Disk: Stores web pages for faster access when used a second
   (third,...) time. OR, if you connected WAN to anything other than
   the hard disk:  Not Used.
   RAM: Stores data used by the CPU OR, if you connected WAN to RAM:
   Stores web pages for faster access when used a second (third,...)
   time.
   CPU: Interprets HTML and determines screen layout.
3. 25 points

a. One possible way:

Table 1 (person table)		Table 2 (package table)

Customer ID (text)
Name (text)			Package Number (text)
Phone (text)			Sender ID (text)
				Recipient ID (text)
				Weight (number)
				Location (text)

b.

Join tables on Recipient ID and Customer ID
Project: Recipient Name
Restrict: location="flight FX287"

4. 26 points

a. setup problem:

	image size: 1024*768*3=2.36 MB
	transfer over 33.6kb/sec modem=702 seconds

spreadsheet: (this is one possible way to do it)

pixel size (in bytes)		(formula=1024*768)
image size (in bits)		24
total image size (in bytes)	B1*(B2/8)
modem speed (in bytes)		3360
seconds to transmit		B3/B4

b.

	1. save spreadsheet in M: drive with the name MODEM.XLS

	2. Click on file transfer icon from windows:
		remote host=wam
		user ID=(your ID)
		password=(your password)
	        click on binary transfer
		highlight MODEM.XLS and click on copy

		OR

		telnet to WAM
	 	FTP ttclass
	   	enter your class user ID and password
	   	cd class
	   	cd lbsc690
	   	cd (your directory)
	   	get MODEM.XLS
	   	quit

	3. Telnet to WAM
	   get into pine
	   c for compose message
	   send to: jharding@wam.umd.edu
	   cc: oard@glue.umd.edu
	   attachment: MODEM.XLS
	   send mail