OS

☆ Posted by admin on 28 Jul 2013 at 11:46 PM View

How are distributed systems different from multicomputer?

[a.] distributed systems are more loosely coupled
b. d.s. are more tightly computer
c. nodes in d.s. do not have cpu
d. nodes in d.s. all run on the same OS


multicomputer also known as cluster
- group of interconnected, whole computers working together as a whole


- same place
- same os
- do not share memory (loosely coupled)



d.s
- anywhere/worldwide
- multiple organization





Tut1

Question 1
1. B
2. B
3. A
4. B
5. C
6. D
7. B
8. C
9. B
10. A

Question 2
a. 42513
b. Programmed I/O, interupt driven I/O, direct memory access
c. will not use too much space on kernel space, run only when it's needed in user space

Question 3
a. 32415
b. buffering, error reporting, allocation of devices, providing device independant block size (slide 22 lecture 1)
c. buffer for incoming or outgoing data to maintain the speed

Question 4
a. lecture 2 slide 23-24
b. failure managment, load balancing, parallelization (compiler and application)
c. lecture 2 slide 27

Changelog

★ Posted by admin on 19 Jul 2013 at 3:11 PM View

v1.1
- config.php for storing constants
- footer constant
- posted by

v1.1.1 (todo)
- move create table sql to install.php

Tutorial 3

☆ Posted by admin on 19 Jul 2013 at 11:14 AM View

1. Match the following to one of the Internet layers
a) Transport Layer
b) Network Layer
c) Network Layer
d) Application Layer
e) Physical Layer
f) Application Layer
g) Transport Layer
h) Network Layer
i) Data Link Layer
j) Data Link Layer
k) Physical Layer

2. What is the difference between network layer delivery and transport layer delivery?

Transport Layer
-between processes (app)
-sender breaks app messages into segments and passes it to network layer
-receiver reassembles the segments into messages and passes to app layer
-UDP, TCP
-needs a port number (socket = ip + port)

Network Layer
-between hosts (pcs, devices)
-packet forwarding / routing
-needs IP address

3. How does a repeater extend the length of a LAN? How is the hub related to a repeater?

-repeater only regenerates/amplifies the signal to its original strength (long distance)

-hub is a multi-port repeater, functions the same


4. What do we mean when we say that a bridge can filter traffic? Why is filtering important

-allows traffic to go to the right link/port/path, blocking it from other ports
-improve the network performance by preventing the network congestion (prevent network flooding, control traffic in the network, ensure the data goes to the right path)


5. In the following figure we are using a bridge. Can we replace the bridge with a router? Explain the consequences.

-yes, a router can function as a bridge, but not the other way round
-consequences:
-overhead. a router has to do more (bridge performs simpler operations, pass the packets to the destination)
-router has to look at the packets and change the MAC address to deliver it to the right destination
-cost more

6. Complete the table in the previous figure after each station has sent a packet to another station.

| Port
A | 1
B | 1
C | 2
D | 2
E | 3
F | 3

7. A bridge uses a filtering table; a router uses a routing table. Can you explain the difference?

-routing algorithms/protocols
-identifies the best route to send the packets to the destination
-based on IP address
-bridge
-filter forward based on MAC address, based on the filtering table
-if no match is found, packets will be sent to all the ports except the receiving port -???

8. Which one has more overhead a repeater or a bridge? Explain your answer

-bridge has more overhead because it needs to forward to the right destination
-repeater just amplifies the signal


9. Which one has more overhead a bridge or a router? Explain your answer
-router has more overhead, change the MAC address, filter based on IP address

10. Explain the four sources of packet delay
a. node processing delay
b. queing delay
c. transmission delay
d. propagation delay

-lecture 5, slide 21

11. What is virtual local area network (VLAN)? What is it used for? Explain it with a diagram if needed.

-VLAN configured by software and not hardware
-grouping people in an organization (easier), load balancing, broadcasting traffic is contained
-lecture 5, slide 40


12. How does a VLAN provide extra security for a network?
-non-members of the VLAN will not receive the message that is not intended for them. (private network, broadcasting traffic is contained)


13. How does a VLAN reduce network traffic?
-VLAN members grouped in one domain, traffic are only circulated in the intended domains, so indirectly it helps the network traffic


14. Compare between MTAs and MAAs and discuss the protocols used by each agent

-and is the push mechanism
-anotehr is pull



15. Why do we need POP3 or IMAP4 for email?
Post Office Protocol (sends out to devices and that's it)
The Internet Message Access Protocol (emails are stored in the server)

-lecture 6, slide 25

when A sends B an email, the SMTP server acts as "mailbox" to collect the mails, since B may not be online all the time, therefore no connection can be established. So the POP3 or IMPA4 is another protocol that does the final delivery, when the user logs in to retrieve the mails from the SMTP server.

16. What is SMTP?
To push messages from the server to wherever you are...


17. What is a proxy server and how is it related to HTTP?
-proxy: intermediate server between client and server
-proxy server acts as cache

TEDxSydney: Beatbox Brilliance

☆ Posted by uimos on 18 Jul 2013 at 5:37 PM View

Duk xu duk xu! Bee Doo Bee Doo!



-uimos

FIRST & FOLLOW

☆ Posted by admin on 18 Jul 2013 at 11:02 AM View

FIRST(program) = { { }
FIRST(statement) = { if, id }
FIRST(if_stmt) = { if }
FIRST(else_part) = { else, e }
FIRST(assign_stmt) = { id }
FIRST(exp) = { 0, 1 }

FOLLOW(program) = { $ }
FOLLOW(statement) = { }, else }
FOLLOW(if_stmt) = { }, else }
FOLLOW(else_part) = { }, else }
FOLLOW(assign_stmt) = { }, else }
FOLLOW(exp) = { ), }, else }

LISP

☆ Posted by admin on 8 Jul 2013 at 6:36 AM View

http://www.afralisp.net/autolisp/tutorials/cond-vs-if.php

http://stackoverflow.com/questions/3767972/displaying-a-string-while-using-cond-in-lisp

http://www.cs.cmu.edu/Groups/AI/html/cltl/clm/node74.html

http://www.ai.sri.com/pkarp/loop.html

http://jtra.cz/stuff/lisp/sclr/mapcar.html

-- http://bybitsandbytes.files.wordpress.com/2007/02/ch03.pdf

THI 3461 Tutorial 1

☆ Posted by admin on 7 Jun 2013 at 3:25 PM View

Question 1
=======
cellphone
-on the go
-personal
-convenient (pre-loaded credit/postpaid)
-convenient for quick call/leaving a message

-personal details such contact lists

public phone
-fixed location
-always available as in cellphone may be limited to coverage area and battery
-nowadays, acts as backup (airport, terminal, outstation)
-may be inconvenient, as telephone cards or coins are required


-durable

-height
-enclosure (privacy weather noise)



Question 2
=======

- takes seconds to play. expectation: press "Play" and it plays.
- play (frequent), record (not as frequent).. time taken will be longer to familiarize with the system
- days - months


Question 3
=======
-as many stakeholders as possible

Yay! First post in February!

☆ Posted by uimos on 3 Feb 2013 at 4:29 PM View

So it's February now!

GONG XI FAI CAI

Happy Valentine's Day!

-uimos

NYAN~

☆ Posted by uimos on 9 Jan 2013 at 11:01 AM View

nyan nyan nyan * infinity

-uimos

Want to search for color?

☆ Posted by uimos on 8 Jan 2013 at 3:20 PM View

http://www.colorhexa.com/

-uimos