Summary

SUMMARISE

  -   Permanent: Data is protected from any alterations.

  -   Sequential access: Storage locations have to be read or written in their correct order starting with the first location.

  -   Random access: Storage location can be directly read or written. Also called ‘direct access’.

        Primary Storage

-   Onboard storage devices built into an information system (e.g. motherboard)

-   Fast, easy to use and accessible at any time

-   Random access memory ( RAM)

·      Found on BIOS.

·      Checks system and loads the operating system.

·      Designed for temporary use only

·      As soon as power is turned off, all contents of RAM are erased.

·      Random

·      Volatile because it needs constant power supply to keep its data.

-   Read only memory ( ROM)

·      Random

·      Not volatile’

·      Permanent [ ROM & PROM only ]. Only permanent MEMORY STORAGE DEVICES. 

Secondary Storage

-   Storage devices attached to an information system

-   More permanent.

-   Provides space for data and software that are not immediately needed by the information system.

-   Hard disks, Floppy discs, CDs.

-   CD

·      Random

·      Not volatile

·      CD Rom, CD- A, CD-R are non recordable DVD.

Volatile

-   Refers to storage decives that will lose all their data if the power is switched off.

  Non-Volatile

-   Opposite

             CPU

-   Wider data bus: Consisting of wires that allow data ti enter and leave the CPU. It controls the number of data bytes that can enter and leave the CPU in a single step.

E.G. one with 64 bits can more 8 bytes of data in or out in one operation.

- Faster clock speed: CPU that operates with a clock speed of 2GHz will obey twice as many instructions in a second as a CPU with a clock speed of 1GHz.c

-  Higher FLOP rating. ( Floating-point Operation ) indicates how many floating point number can be added together in a second. It is considered to be more reliable indicator of CPU speed than clock speed.

- Is working in parallel with other CPUs. If the information system contains multiple CPUs then it may be possible to divide the analysing process between them so that each CPU gets a shorter list of task to perform. 

Motherboard

-   Central printed circuit board in many modern computers which holds many of the crucical components of the system, while providing connectors for other peripherals.

-   Also known as the main board, system board.

-   Include:

·      sockets

·      chipset

·      non-volatile memory

·      clock generator

·      slots for expansion cards

·      power connectors.

DISPLAYS –CRT, LCD

       CRT ( Cathode Ray Tube)

-   Sealed vacuum tube that can fire and accurately focus beams of electrons on a chemically coated screen.

-   Problems

·      Bulky and heavy

·      Uses a lot of electricity

·      Scan line refresh tech. can produce noticeable flicker.

-   Its alright: manufacture, produces bright, clear display, viewed from all angles

LCD ( Liquid Crystal Display)

-   Uses a material that switches between blocking light and allowing it to pass through when an electric current is applied.

-   LIKE CRT organised into pixels, each containing group of three crystals. 

Activities pg 145

nREMEMBER
1. Random Access: That any storage location can be directly read or written.
* It is also called "direct access"
 Storage device:
-DVD
-USB Memory Device
-Hard Disk Drives
2.Sequential Access: That any storage locations have to be read or written in their correct order, starting with the first location.
Storage Device:
- Tape
3. Volatile: Storage devices that will lose all their data is the power is switched off.
- RAM not volatile

THINK
4. RAM is the only volatile storage device as it needs a constant power supply to keep its data.
- Refreshed

- SSD ( Sold State Drives): Instead of using hard disk drive, they use flash memory. They are secondary storage, form role of hard disk, but use flash memory. They are not removable
Advantages:
- Fast
- No moving parts, thereby don't tend to crash.
- No motor to fail
- No read write head to crash

- How long can they last?
- Solid State Drive: Like having memory sticks within the computer.
- Solid State Drive good for cameras, due to the environment cameras are used in.

* Hard Disk Drive: Motor which spins the disk, 7000 revolutions/minute. Floating above it, delicate wafer, devices that can magnetic fields and generate magnetic field. Disk has ion compound and can be ionised. Can read magnetic patterns of disk.
* Read write head, crashes onto the surface: it destroys the surface, regions on the disk that are corrupt. Not hard to corrupt hard disk.
5. Sequential access devices are better suited for storing backup data due to [its speed problem.]
Note: It is the slowest, especially if data is at the other end of the tape.
- there are tape systems which record the position of every file on the tape.
- it then uses fast forward and fast rewind to move quickly to the file.
- in saying this their speed is significantly slower than disk access.
Therefore better suited for storing back up data as well as long term data storage.

Activities pg 141

REMEMBER
1. The most common type of RAM used in computers are:
- SDRAM ( Synchronous)
2. EE ( electronically erasable) EEPROM is the most useful of the ROM type of memories as:
- data can be erased by exposing the chip to ultraviolet light.
- new data can be added
3. Optical storage devices store data as light- false

THINK
4. PROM would be an ideal storage device for security data as:
- prevents any alteration of the data
- once the data is added it cannot be changed.
5. Examples of situations where CD-R is a better choice for data storage than CD-RW is:
- For archiving, CD-R will be a better choice/
Note:
-->CD-R ( CD Recordable) technology uses a coloured dye that can be changed by heating to permanently record data.
--> CD-RW ( CD- ReWriteable) technology uses a dye that can be switched betweeen cloudy and transparent.

6. 3.5 inch floppy disks have changed very little since they were first introduced in the mid 1980's- that makes them old technololggy.
 Reasons for their continued popularity include:
- they are still partially compatiable
-" higher density drives are built to read, write and format lower density media without problems, provided the correct media is used."

RESPOND using assess
7. The advantages and disadvantages of flash storage devicesd as replacements for floppy devices are as follows:
Advantages- Flash memory storage devices
- fast and do not require any power to keep data in storage.
- smaller, more compact
- capacity- much bigger
- once data is written into the chip by applying an electric charge to each memory location, its electric charge is trapped and does not need any electric power to be kept there.
- no moving parts, thereby there is no issue of significant danger being done to wipe out or corrupt data in any way.
Advantages- Flash RAM
- uses less power but requires a small electric curren to remember its stored data.
- better suited for small, low power portable devices.
Diadvantages
- higher cost
- contents of an entire flash memory chip can be erased in a single operation.

MAGNETIC FIELDS
- Magnetic
- If on floppy disk, contents can get deleted.

Collection Hardware: Barcode Scanners

 My Powerpoint Presentation can be viewed on the school website!

Collection Hardware

Biometrics Scanners

--> Examples:

-        - DNA

-        - Iris scanning

   * Prevents:

-        - Identity fraud

-        - Can be used for passwords

--> Modern day examples:

-        - In Walt Disney: Passes aern’t being shared

-        - Japan uses palm vein identification

-->Specifications:

-        - Scanning patterns on fingerprints .

-        - Can fool scanners, have moulds of fingerprints.

-        - Larger area

--> Functions:

-        How biometric scanner identifies the input sample by comparing it to exisiting template.

-       
     Fingerprint

*Forensics

*Security

--> Optical recognition

-        - Takes 2 seconds to scan the iris, more accurate method of fingerprint.

--> Fallbacks

-        - Difficulty scanning because of glasses and contacts

Voice Recorder & Microphones

--> Typical use:

 - Record and playback of data that is fed to the voice recorder verbally.

--> Applications:

-        - Pen recorder

-        - Black box

-        - Camera phone

-        - Cellular phone

-        -  Hearing aids

--> Data transferred:

-        - Through USB interface from hardware to computer.

-        - Talking directly into the voice recorder.

-        - Entertainment purposes

Carbon Microphones:

Dynamic Microphones:

Ribbon Microphones:

Condenser Microphones:

Crystal Microphones

Vibrating air particles converted in signals

BLACK BOXES:

-        - Time

-        - Pressure altitude

*Bigger sample- more variations

Note: When digitising sound, we need to consider the following:

-  Mono or stereo

-  Sample rate (bits per second), the higher the sample rate, more true to life! E.G. 144kb/s

-  Sample Size (kilo bits, Mega bits): Larger SS, more variations are allowed: E.G. High or Low frequencies, loud or soft. [To know in the exam] E.G. 16 Bits

      Digital Instruments

        

-->  Uses:

-        - Anywhere live music is there.

-        - School’s music department.

-        - Midi Files are a text document, using little disk space.

-        - BUT you need MIDI compatible hardware or software to record and playback MIDI files.

      Graphics Tablet

-        - Also called a digitizing tablet

-        - Alternate input device allowing you to draw hand draw images & other graphics.

 --> Uses:

-        - In East Asia, different characters.

-        - Artists use it in conjunction with Adobe.

-        - Also used for Audio Haptic products where blind or visually impaired people touch swelled graphics on a graphic tablet and get audio feedback from it.

--> Types:

-        - Passive

-        - Active

-        - Optical Acoustic

-        - Electromagnetic

-        * Received signal can also determine distance of stylus from surface of tablet, tilt etc....

--> Data Transfer:

-        - Transferred through USB interface which connects tablet to computer

-        - Transferred through Bluetooth of tablet.

-        - Finer detail, accurate image

--> Specifications:

-        -  Resolution

  Camera; Still & Video

--> Uses:

-        - STILL: capturing still images

-        - Capturing video

-        - Recording video

-        - VIDEO: capturing video & sound

--> Types:

-        - STILL: SLR, DSLR

-        - VIDEO: Camcorders, high definition video camera, closed circuit television camera

--> BITTER OPTICS: Digital SLR

-->Specifications

-        - STILL: Average 10-14 megapixels

-        - Av. 3-6 times optical zoom ( physical lens moving)

-        - Records sound

-        - VIDEO: HD or SD video

-        - Stereo sound capture

-        - Different file formats

-        -Averages between 20-200 frames/second

--> Data Transfer:

-        - USB cable

-        - HDMI cable- HDTV’s

-        - RCA cable

-        - Wi-Fi connectivity

-        - Memory card

-        - PictBridge connectivity for digital still cameras

- CCD Device: light sensitive, push button, light, current ( analogue signal)a digital signal  - Image, cameras have onboard processer, and processes. IS CAPTURING ANALOGUE - - INFO- LIGHT, converting into digital format!

Keyboards & Mouse

--> Mouse:

-        - Light emitting diode+ photodiodes to detect movements relative to underlying surface rather than moving some of its parts as in a mechanical mouse.

--> Keyboards:

-        - Are connected to the computer via wires and cords. These W& C transmit info. To computer so that it appears on the screen.

-        - Most Keyboards allow 250 characters, press SHIFT.

-        - Different types of keyboards:

-        QWERTY

-        DOBARIC – common letters in the home row!

 RFID: Radio Frequency Identification

 Small electronic devices that contain a chip.

--> Uses:

-       - In car

-       - Animal tracking tags

-       - Credit Card shaped for use in applications

-       - E-tags; has  a battery: receives signal, then transmits

-         

--> Specifications:

-        - RFID Tags

-        - Then antenna picks it up

-        - Computer picks it up

--> Consists of:

-        - An antenna or cord

-        - Transceiver ( with decoder)

-        - A transponder ( RF Tag) electronically programmed with unique information. [label]

-        - Must have RFID receiver on computer which can decode the signal.

-        - Different levels of frequency determines what that particular RFID is used for (low. Med, high).

--> How is data transferred?

-        - Car goes through etag scanner, sending number to receiver, its matched up (database) this 12 digit number matches up with the car (number plate).

Scanners:

--> Types:

-        - Sheet : Can scan photos

-        - Flatbed: Books that are bound.

-        - Handheld:

-        - Pen based

--> How it works:

-        - CCD- records, produces light- then the CCD receives the reflected light.

-        - Light source

-        - Guide rails

-        - Motor

-        Toothed belt

-        Toothed pulley

--> Data transfer

-        USB