Review

							         COSC1078 Introduction to
          Information Technology
                           Lecture 13


                Revision and Review
                          James Harland
                     james.harland@rmit.edu.au


Lecture 13: Review                      Intro to IT
Introduction to IT
1-4 Introduction, Images, Audio, Video
5-6 Computer Fundamentals        Assignment 1, WebLearn Test 1


7 Review

8 Operating Systems          WebLearn Test 2
9 Operating Systems          Assignment 2
10 Internet
11 Internet Security         WebLearn Test 3
12 Future of IT              Assignment 3, Peer and Self Assessment


 Lecture 13: Review                      Intro to IT
Overview

 Questions?

 Hexadecimal


 Two’s complement


 Flip flops


 Questions?

Lecture 13: Review   Intro to IT
Review / Catch Up...

 Continues tomorrow


 “Repeat the last two lectures”


 Any other suggestions?




Lecture 13: Review                 Intro to IT
Assignment 2

You will need to find audio files containing:
 Human voice speaking in English (at least one minute)
 Music including singing (at least two minutes)
 Music with no singing (at least three minutes)
 No copyrighted material!


You will also need to use (but not copy or `rip’)
  your favourite music CD

Lecture 13: Review                  Intro to IT
Assignment 2

The following may be useful:


 Internet Audio Archive www.archive.org/details/audio
 Classic Cat             www.classiccat.net
 LADSPA plug-ins for Audacity


o Assignment requirements ready `soon’
o Start choosing files etc. now


Lecture 13: Review                 Intro to IT
Hexadecimal
01010100001010101010100110100010101001101001010010
100011100010101010100101111001001010…




 AF136DF738CA23895389BCFE5C36A63B…



 Lecture 13: Review            Intro to IT
Two’s complement
01010100001010101010100110100010101001101001010010
100011100010101010100101111001001010…




   X=4+6

   X = 13 -5




 Lecture 13: Review            Intro to IT
Flip-flops
01010100001010101010100110100010101001101001010010
100011100010101010100101111001001010…




   ???

 Lecture 13: Review            Intro to IT
Hexadecimal
 Notation for binary numbers
 More compact than 1001010001010101001010...
 NOT decimal (0-9)
 Base 16: 9 + 9 = 1 x 16 + 2 x12
0   0000         4 0100   8 1000   C    1100
1   0001         5 0101   9 1001   D   1101
2   0010         6 0110   A 1010   E   1110
3   0011         7 0111   B 1011   F    1111


 Lecture 13: Review                Intro to IT
Two’s complement
01010100001010101010100110100010101001101001010010
100011100010101010100101111001001010…




   X=4+6

   X = 13 -5




 Lecture 13: Review            Intro to IT
Numbers

 Represented in binary notation

 25 in ASCII is 00110010 00110101

 8 bits per digit seems too much!

 Can represent 256 numbers in 8 bits …

 Don’t want to add, multiply etc. in ASCII …

 Remember that 1 + 1 = 10 …
Lecture 13: Review             Intro to IT
Two’s Complement

 Bit pattern         Value
 011                 3
 010                 2
 001                 1
 000                 0
 111                 -1
                             How do you store
                             negative numbers?
 110                 -2
 101                 -3
 100                 -4


Lecture 13: Review                 Intro to IT
Two’s Complement

                                   Bit pattern   Value
0 first means +ve (sign bit)
                                   011           3
1 first means –ve
+ve: Count from 0 up to 01n-1      010           2
-ve: Start from 1n down to 10n-1   001           1
3 is 011, -3 is 101                000           0
2 is 010, -2 is 110                111           -1
1 is 001, -1 is 111                110           -2
                                   101           -3
                                   100           -4



Lecture 13: Review             Intro to IT
Two’s Complement

                                   Bit pattern   Value
1 + 2: add in obvious way
                                   011           3
3 – 1: calculate as 3 + (-1)
011 + 111 = 1010                   010           2
Answer is 010, ie 2.               001           1
Can add and subtract with          000           0
the same circuits                  111           -1
                                   110           -2
                                   101           -3
                                   100           -4



Lecture 13: Review             Intro to IT
Excess Notation

                                    Bit pattern   Value
A different encoding of the
                                    111           3
numbers
“naive” bit pattern encodes 4       110           2
more than actual value              101           1
100 (looks like 4) encodes 0        100           0
101 (looks like 5) encodes 1        011           -1
110 (looks like 6) encodes 2        010           -2
                                    001           -3
                                    000           -4



Lecture 13: Review              Intro to IT
Gates and circuits


 1
 0
                     or            1
                                   0
 0
 1
                           1
                           0
  1
  0                  and   1
                           0

  0
  1                  not   1
                           0


Lecture 13: Review             Intro to IT
Gates and circuits


  No storage here

  Results instantaneously available

  Disappear when inputs change

  How can a bit be `stored’?



Lecture 13: Review              Intro to IT
Memory via `Flip flops’


 0                         0
                     or                  0
                               0


  0                  and
                           0
                           1
  0
  1                  not


Lecture 13: Review                 Intro to IT
Memory via `Flip flops’


 01                        1
                     or                  1
                               1


  1                  and
                           1
  0                  not


Lecture 13: Review                 Intro to IT
Memory via `Flip flops’

 Can design other versions of flip-flops

 Shows how circuits can be designed using
AND, OR, NOT (NAND, NOR, XOR, …) in
combinations (gates)

 Hierarchy and abstraction

 Shows how electric circuits can store
values

Lecture 9: Computer Fundamentals   Intro to IT
Conclusion


 Assignment 2 specified sometime this week



 Finish reading book!




Lecture 13: Review           Intro to IT