COSC1078 Introduction to
Information Technology
Lecture 9
Data Storage Devices
James Harland
james.harland@rmit.edu.au
Lecture 9: Data Storage Devices
Intro to IT
Introduction
Who is this bloke?
Lecture 9: Video
Intro to IT
Introduction
Lecture 9: Data Storage Devices
Intro to IT
Overview
 Questions?
 WebLearn Test 1
 Assignment 1
 Binary Representation
 Questions?
Lecture 9: Video
Intro to IT
Introduction to IT
1 Introduction
2 Images
3 Audio
4 Video
WebLearnTest 1
5 Binary Representation
Assignment 1
6 Data Storage
7 Machine Processing
8 Operating Systems
WebLearn Test 1
9 Processes
Assignment 2
10 Internet
11 Internet Security
WebLearn Test 3
12 Future of IT
Assignment 3, Peer and Self Assessment
Lecture 9: Audio
Intro to IT
Questions?
How did you spend 6-8 hours on this course
last week?
This week?
Lecture 9: Video
SE Fundamentals
Assessment Process
 Submit all assignments via Blackboard in the
Learning Hub
 Assignment 1 due 11.59pm Sunday 1st April
 Assignment 2 due 11.59pm Sunday 6th May
 Assignment 3 due 11.59pm Sunday 27th May
 Late assignments attract a penalty of 10% per
day late, up to a maximum of 50%
Lecture 9: Video
Intro to IT
Assignment
 Assignment will be in three parts
 Overall task is to produce a video
 Groups of up to 3
 Assessed by final video and group blog
 Part 1: images and audio (end of week 5)
 Part2: hardware (end of week 9)
 Part 3: reflection, research (end of week 12)
Lecture 9: Video
Intro to IT
Assignment 1
 Use GIMP (or a similar tool) to perform some
manipulations on an image
 Use Audacity to perform some manipulations on sound
 Use a movie making tool to produce something like (and
much better than!) ‘Lord of the Controllers 1 & 2’
 Email me your group and its name so that I can set up
a blog on the Learning Hub
Lecture 9: Video
Intro to IT
Overview
01010100001010101010100110100010101001101001010010
100011100010101010100101111001001010…
Lecture 9: Data Storage Devices
Intro to IT
What do computers do?
 Compute!
 Input/Output
 Processing
 Memory
Lecture 9: Data Storage Devices
Intro to IT
History
 …
 Babbage’s Difference Engine (1849)
 Babbage’s Analytical Engine (1837-1871, never built)
 Turing’s Universal Machine (1936, mathematical model)
 Turing digital Boolean-logic multiplier (1937)
 Colossus (1943, destroyed 1945)
 ENIAC (1946)
 Von Neumann architecture (c. 1945)
 EDVAC (1949)
 CSIRAC (1949)
Lecture 9: Data Storage Devices
Intro to IT
Overview
“Thomas the Tank Engine”
Lecture 9: Data Storage Devices
Intro to IT
Overview
Video
Audio
Text
Thumbnails
Lecture 9: Data Storage Devices
Intro to IT
Memory via `Flip flops’
0
or
0
0
0
0
01
and
0
1
not
Lecture 9: Data Storage Devices
Intro to IT
Memory via `Flip flops’
01
or
1
1
1
1
and
1
0
not
Lecture 9: Data Storage Devices
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: Data Storage Devices
Intro to IT
Computer Memory
Cells of 8 bits each (one byte)
…
Most
significant
bit
address
Lecture 9: Data Storage Devices
…
Least
significant
bit
Intro to IT
Random Access Memory (RAM)
 Random access means any cell can be accessed at any
time (and in any order)
 Volatile – contents cleared when machine is switched off
 Very fast compared to other forms of memory
 DRAM: dynamic RAM (replenishes charges constantly)
 SDRAM: synchronous DRAM – faster still
 Often have small very fast caches and registers
Lecture 9: Data Storage Devices
Intro to IT
Magnetic Disk
 Thin spinning metal disk with magnetic coating
 Each disk contains a number of circular tracks
 Often several disks stacked on top of each other
 Cylinders made up of tracks made up of sectors
 Can have very large storage this way
 Slow access time!
Lecture 9: Data Storage Devices
Intro to IT
Magnetic Disk (Hard Disk)
Seek time: move heads from one track to another
Latency time: half time for complete disk rotation
Access time: seek time + latency time
Transfer rate: rate data can be read from disk
`Typical’ Hard disk
Seek time: 2ms to 15ms
Latency time: 8ms to 20ms
Transfer rate: 0.5 GB per second
Sounds fast, but is actually quite slow …
Lecture 9: Data Storage Devices
Intro to IT
Optical Disks (CDs, DVDs)
Laser readers rather than magnetic ones
Disks more error-tolerant than magnetic ones
Type
Features
Date
Storage
CD
“compact disk”
1984
800MB
DVD
Multiple layers
1995
15GB
Blu-ray
`blue laser’
2004
100GB
(405 vs 650 nm)
Lecture 9: Data Storage Devices
Intro to IT
Flash Drives
 Disks of all sorts are slow compared to other circuits
 Flash drives ‘write’ small electronic circuits
 Eventually decay after many changes of data
 Suitable for slow-changing data, not main memory
 Portable and much more resilient than disks
Lecture 9: Data Storage Devices
Intro to IT
Older Storage Types
Magnetic tape
`Floppy’ disk
(5.25’’ disk)
3.5’’ disk
Lecture 9: Data Storage Devices
Intro to IT
Conclusion
 Get Assignment done this week
 Don’t forget to blog …
 Keep reading! (book particularly)
Lecture 9: Data Storage Devices
Intro to IT