FY04: Course Information Autumn Term Jennifer George Email: mas02jg@gold.ac.uk Office Hours: Mondays 3.00pm 5.00pm (email for appointments) Office: Room 4, 29 St James 1
Lectures & Labs Lectures: RHB 306 Time 1.00pm 3.00pm Labs Whitehead Building 300 & 316 Time 9.00-10.00 & 10.00-11.00 I ll split the class into two and the times you come will alternate Lectures & Labs Two completely independent sets of information Lectures deal with exam Labs deal with the coursework Attendance at lectures is at your own discretion so is the exam. If you email me in advance that you cannot attend a lecture I will help you during surgery hour, if not, you have to take responsibility 2
Course Assessment: 2 Coursework 70% Exam 30% Lecture notes and lab sheets: http://doc.gold.ac.uk/~mas02jg/fy04/ Lecture Structure 1. Storage and File Systems 2. Files and Characters 3. Processor 4. Logic Gates 5. Operating Systems 6. Internet 7. Email and Web 8. Users 9. Legal Issues 10. Revision 3
Lab Structure 1. SSH and VNC 2. The GNOME Desktop 3. Emacs 4. Text Encoding 5. Advanced Text Editing 6. Command Line Shell 7. HTML 8. Network Tools 9. Network Protocol 10. Apache Web Server 4
Hardware Components Monitor Components of a simple personal computer 5
Number systems Binary 2 states, on status (1), off status (0) Each state is a binary digit 8 bits = 1 byte (smallest word) 1024 bytes = 1 kilobyte (kb) 1024 kb = 1 megabyte (MB) 1024 MB = 1 gigabyte (GB) 1024 GB = 1 terabyte (TB) Average CD=740 MB Average USB stick: 1 16GB Average Built in /External Hard Drive: 320GB 6
Punch Cards Jacquard loom (1801) Early computers Hole = 1 No hole = 0 Obsolete since 1970s Random Access Memory (RAM) A chip on which information such as the operating system is stored. a few GB in modern PCs Very fast (nano seconds) 100% electronic Volatile (needs power) This is the working memory which means that when the computer is switched off, any information that has been modified (such as the settings) is lost. This is why you restart the computer when the operating system freezes. It restores original settings. 7
RAM RAM makes computers work faster This is beneficial when you are running applications paralellly Read Only Memory - ROM Also known as Firmware Read only Memory A chip on which information is permanently stored. It tells the computer what to do. Example = When the computer is switched on it tells the computer to search for the operating system. 8
Why use removable storage? Why is removable storage is useful? Making back-up copies of important information. Transporting data between two computers. Storing software and information that you don't need to access constantly. Copying information to give to someone else. Securing information that you don't want anyone else to access. Modern removable storage devices offer an incredible number of options, with storage capacities ranging from the 1.44 megabytes (MB) of a standard floppy to the upwards of 60 to 80-gigabyte (GB) capacity of some portable drives. 9
Storage Storage of media can be broken down into several categories: Magnetic Storage Tapes Hard drives (not always removable) Floppy Zips Jaz Optical Storage CDs DVDs Magneto-Optical MiniDiscs MO Discs Solid State Storage Compact flash Smart Media Storage Non-volatile Large capacity Low cost Used for archival storage On-line vs. off-line Often mechanical (so slow) 10
Magnetic Storage Tapes Hard drives (not always removable) Floppy Zips Jaz 11
What is Magnetic Media? The most common and enduring form of removable-storage technology is magnetic storage. The magnetic medium can be easily erased and rewritten, and it will "remember" things stored onto the medium for many years. How does magnetic storage work? The storage media is typically called a disk or a cartridge. The drive generally uses a motor to rotate the media at a high speed. At this speed it accesses (reads) the stored information using small devices called heads. The heads pull or push the signal of data so that they can be read or stored. 12
Tape In the audio realm, magnetic tape (in the form of compact cassettes) used to be a popular way of distributing music. In the video realm, video tape is used widely both in the broadcast industry and at home to store material for later viewing on VCRs. Two other types of tape used in audio: ADAT DAT 13
Magnetic Tape 1951: 1000 bits/inch 2008: about 10! bits/inch (100MB) per inch Low-cost per bit High-capacity (1TB) Reliable Very slow access Archival storage 14
Hard Disks Nearly every computer that is made today contains one or more hard disks. Hard disks store changing digital information. Hard disks save your files! A file is simply a named collection of bytes. The hard disk is favoured over storing on tapes because so much more information can be stored in a smaller space. A typical desktop machine will have a hard disk with a capacity of between 80 and 320+ gigabytes. Hard Disks Much faster than floppy Sealed unit Floating head Capacity increasing much faster than access 1980: 5 MB 1995: 1 GB, 2008: 1.5 TB 15
Floppy Disks Technology used for almost 30 years It was possible to store entire operating systems at one point Magnetic disk in shell 1972: 175 kb 1987: 1.44 MB Now rarely used Small capacity Bulky Easily damaged 16
Zip disks The main thing that separates a Zip disk from a floppy disk is the magnetic coating used. On a Zip disk, the coating is of a much higher quality. The higher-quality coating means that the read/write head on a Zip disk can be significantly smaller than on a floppy disk. The smaller head means that a Zip drive can pack thousands of tracks per inch on the disk surface. Zip drives can hold between: 100 to 750 Megabytes 17
Jaz drives Another method of using magnetic technology for removable storage is essentially taking a hard disk and putting it in a self-contained case. One of the more successful products using this method is the Iomega Jaz. Each Jaz cartridge is basically a hard disk, with several platters, contained in a hard, plastic case. 18
Portable hard drives There are other smaller hard drive mechanisms on the market They are much cheaper than they used to be If you want to take a copy of your work home, invest in a USB Stick 2GB will be sufficient. 320 GB Seagate FreeAgent Portable Drive - 60.00 1TB Seagate FreeAgent jennifer Portable george Drive - 80.00 1 16GB USB Sticks - 6.00-20.00 19
Optical Media Reflective surface Read by laser 1985: CD 600 MB 1995: DVD 4.7 GB 2008: Blu-Ray 50 GB 20
How does optical media work? The optical storage device that most of us are familiar with is the compact disc (CD). A CD R can store huge amounts of digital information on a very small surface. The design that makes this possible is a simple one: The CD surface is a mirror covered with billions of tiny bumps (CD Rs) or pits for (CDs) that are arranged in a long, tightly wound spiral. Pit The CD player reads the bumps/pits with a precise laser and interprets the information as bits of data. 21
CD-ROM, R and RW CD-ROM = CD Read Only Can only be read CD-R = CD Recordable Can store information Can add to the disk,but you cannot remove information CD-RW = CD Rewritable Can add and remove information CDs CDs are used to hold music, data or computer software etc. Compact discs are easy and cheap to produce. And if you have a computer and CD-R drive, you can create your own CDs, including any information you want. In order to store on a CD you need a CD Writer (Burner)! 22
DVDs Digital versatile disc or digital video disc Nearly every movie produced today is available on DVD, and many older movies are being moved to the DVD format. Often, a movie comes out on DVD before it comes out on video tape, because the manufacturing and distribution costs for DVDs are so much lower! 23
DVD Three formats developed 1. DVD-R/RW: Recordable format 4.71GB 2. DVD+R/RW: Used for non-volatile data storage such as video 4.71GB 3. DVD-RAM Built in error control and reliable system Easily written and erased used for camcorders, cameras, etc. What is a DVD? A DVD is very similar to a CD, but it has a much larger data capacity. A standard DVD holds about seven times more data than a CD does. This huge capacity means that a DVD has enough room to store a full-length movie, as well as a lot of other information. 24
CDs vs. DVDs More information is stored within the same height disk through the use of layers and smaller size pits. In order to store on a DVD you need a special DVD burner. DVD CD 25
MiniDisc Created by Sony Holds up to 130 Megabytes of information but up to 74 minutes of music! How can it hold this much? This was made possible by a special compression format called ATRAC. Adaptive transform acoustic coding Mini Disks were created because at the time, CDs were not recordable and MiniDiscs were. Pre-recorded MiniDiscs are purely optical. Recordable MiniDiscs use a blend of optical and magnetic technologies. 26
MO Disks The MO (magneto-optical) disks can hold up to 640 Megabytes of information. However, they can only hold 10 minutes of high quality audio. They cannot hold as much as the mini disk because they do not compress files. 27
Solid State Storage Non-volatile circuitry No moving parts Very fast Resists damage Memory cards, USB drives (few GBs) Less reliable long-term Solid-state drives for laptops 28
Flash memory A very popular type of removable storage for small devices, such as digital cameras and PDAs, is Flash memory. Flash memory is a type of solid-state technology, which basically means that there are no moving parts. Inside the chip is a grid of columns and rows, with a twotransistor cell at each intersecting point on the grid. This technology requires a special process to alter the electrical charge which is in turn interpreted into blocks of data by the device. Flash memory Two common types of flash memory are CompactFlash or SmartMedia cards. These can range from 1GB - 16GB These are stored inside the device and the information on these cards can be downloaded to your computer, usually using a USB connection. These are used for digital cameras, pda devices etc 29
Network Storage Storing data online The Cloud Gmail Picasa Google Docs... 30
What external media will you use in this class? CD-Rs and CD-RWs I will demonstrate how to burn a cd tomorrow. External Mini Drives (highly recommended) You should always back up your work on more than one disk or cd, just to be safe. You do not get extra time if you loose your course work. External Drive Management Don t work off your external drive, it will kill it. In other words, don t just double click on something to open it. Drag a copy to the desktop or students folder and work from there. 31
Printing Please do not print loads of copies of information without a good reason. Make sure that the printer you are using is switch on and that it contains paper. Make sure to select the correct printer when you choose file > print. 32
Interfaces Part One - Parallel Ways to connect to the computer: SCSI - Small Computer Systems Interface A peripheral connection system used to transfer large amounts of data. Sometimes used to connect scanners, CD-ROM s, External drives and some printers. IDE Interface - Integrated Drive Electronics Internal connection system used to connect to internal hard drives, cd-roms etc.. Standard for both Macs and PCs Interfaces Part Two - Serial Ways to connect to the computer: USB- Universal Serial Bus Easy to use port for connecting external devices. Standard on almost all computers. Used for web cams, printers, scanners, tablets and so much more.. Transfer Rate: 12Mbits/Sec New version 2: up to 400Mbits/Sec Firewire High-speed serial input/output port developed by Apple. One of the fastest peripheral standards ever developed. Used for video recorders etc. Transfer Rate: 400Mbits/Sec New version 2: up to 800Mbits/Sec 33
Expansion Slots By plugging in special cards into the computer, your computer can perform certain tasks more efficiently or add new functionality. These cards are plugged directly into the motherboard expansion slots which are located inside the CPU. Two Important types of Expansion slots: PCI Peripheral Component Interconnect Fast speed card slot that can be used for modems, audio and graphics cards. AGP Accelerated Graphics Port Specialized type of PCI that is dedicated to GRAPHICS. 34
Burning a CD/DVD To store information on a CD/DVD you must burn it. You don t drag a file over like you would with a disk. There are two types of CD/DVDs that you can store data on. -R (recordable) - Most dependable Once you burn it, you cannot erase it. You can add to it if you set it up correctly. -RW (re-writable) You can put information on and take it off. Disks made on a CD-RW can only be read on a CD-RW drive. I have had variable results with the RW! They can only be read by a computer with a RW drive. Burning a CD/DVD: Directions Make sure that the file you would like to burn is saved and closed Insert a CDR/CDRW/DVD Name your CD/DVD and hit Toast 35
Files Files are persistent stores for data Files have names, used to retrieve contents Name 01010110111010011 Some restrictions on name DOS, early Windows: 8 characters (+3 extension) Mac OS 9: no : Typical: no longer than 255 characters, no / 36
Directories Directories contain a set of files Hierarchical filesystem directories contain directories (dir1/dir2/file) Root directory (called / ) Unix Directory Layout A file named foo in the directory bin inside the directory usr is identified as /usr/bin/foo 37
Linux Directory Layout Mac OS Directory Layout 38
Drives Windows Only Each drive is a storage device attached to the computer Floppy disk Hard disk DVD drive Network drive... Each drive has its own directory tree Windows Directory Layout 39
Group Exercise In groups of 3 or 4 Access a phone or laptop Start to map the device s filesystem Network Filesystems Filesystems can be shared across networks. Files on Unix (blue) shared to Windows (red) 40
Summary Mass storage: hard disks, optical, flash Huge increases in capacity over years Filesystems Files and directories Unix, OS X and Windows all different Windows also uses drives Can be shared over network 41