CHAPTER 3

ICT IGCSE

Term Project Grade 9 Section BDue december 18

•Find and research one Emerging technology not studied in class. It can be a prototype or already available in the market.•Each student must present their findings

•Must use microsoft powerpoint •Presentation must have pictures and at least 5 slides, including a list of references

•Student should be prepared to answer questions about their topic

The memory that a computer uses as a temporary work area is called Random Access Memory. The computer adds data and removes data from this memory. RAM is erased when the computer shuts off (volatile memory).

When a computer is switch on, the operating system is copied into the RAM, any software that is run (such as Microsoft Excel) is also loaded into RAM and run from there. When a file is loaded (such as an excel file) that is also loaded into RAM.

Main Memory - RAM

Main Memory - ROM

Backing Storage

Backup Copy

Read Only Memory permanently stores data (non-volatile), can not be changed by the user. Usually only contains the instructions to initialize and start up your computer; program cycles in a washing machine/program instructions in games such as gameboys, playstations, etc.

Place where data can be stored long term and be changeable. The only systems that do not need backing storage are those systems that are embedded in things, like washing machines.

Making an extra copy of the data on your computer in case something happens to damage or delete your data.

Comparing Main Memory with Backing Storage It is always faster to access data from main

memory than from backing storage. The processor can only use data and instructions that are in memory.

Data stored in main memory is lost when the computer is turned off but data stored in backing storage is not lost.

When programs are run or data files are loaded the contents are copied from the backing storage to the main memory of the computer

Main memory is much smaller than backing storage. It is far too small to hold the data and programs that would be on the backing storage.

STORAGE DEVICES

Storage Medium = the part that holds the data

Storage Device = the machine that lets you store data on the medium and read data from it

3 Types of Storage Devices

Magnetic

• Tiny areas on the surface of the media can be magnetised in different ways and these store bits in codes that represent characters.

Optical

• Store data on their surface by little ‘pits’ burnt by laser into the surface

Solid State

• Different from magnetic and optical, has no moving parts, fits directly into the computer

Magnetic

• Fixed Hard Disk

• Portable Hard Disk

• Magnetic Tape

• Floppy Disk (almost obsolete)

Optical

• CD/DVD –ROM

• CD/DVD –R

• CD/DVD-RW

• DVD-RAM

• Blu-Ray

Solid State

• Memory Stick/Pen Drive/USB

• Flash Memory

Fixed Hard Drives Used as main storage because

They can store very large amounts of data Access to the data is fast There is no limit to the number of times they

can delete data and then reuse the medium Used to store 3 types of data

Operating system Applications User’s data, files, videos, etc.

These 3 types of data are all stored on the hard disk and then sent to the computers memory when they need to be used.

Stores and retrieves data much faster than a CD/DVD Hard disks can crash. That is when read/write head

crashes down on the surface of the hard disk (can cause data loss); fragile

Portable Hard Disk

More robust than fixed hard disk; but can be damaged if dropped or mishandled

Used primarily to backup files and for transferring large files from one computer to another.

Data access times are fast; data transfer rate is fast; large capacity

Transfer rates are NOT as fast as fixed hard disks; more expensive than other forms of media

Magnetic Tape Magnetic tapes are very thin strips of plastic

that are coated with a magnetic layer and are fed through a read/write head mechanism.

Used in any application that requires an extremely large storage capacity and where the speed of accessing data is not that important. Batch processing Utility billing systems – where all customer bills are

produced at the same time and every customer record has to be processed

Making backups (usually larger organisations) Cheaper than using disks; robust; data transfer

rate is fast Access to data is slow; updating requires a new

tape to be created

More than 60,000 slots for magnetic tape cassettesData Archiving

• There is no need to read through the whole disk to find just one piece of data, which speeds up the process considerably

• Fixed Hard Drive• Portable Hard Drive

Direct Access to Data

• Data is stored one piece after the other• Sequential storage (data is arranged in

some sort of order, for example: alphabetical)

• Magnetic Tapes – used when there is a need to store large amounts of data and where the speed of access is not important.

Serial Storag

e

OPTICAL STORAGE DEVICES

CD/DVD RCD/DVD ROMCD/DVD RWDVD RAMBLU RAY

Properties Uses Advantages Disadvantages

CD/DVD ROM

Read Only Memory

Can NOT be recorded on

Storing music albums, software, games, etc.

More robust and cheaper than hard disks

Data access rates are longer than for hard disks

CD/DVD R

Read & Write Once Memory

CAN be recorded ONCE

Home recordings of music and films; storing and transferring data

Once burned they cannot be accidentally written over

If a mistake is made it must be thrown away

CD/DVD RW

Rewritable optical disks

Can be written over several times

Used for data and recording TV shows, etc. that need to be deleted and rewritten

Can be used more than once

More costly ; Can be accidentally overwritten

DVD RAM

Possible to record and use at the same time

General data storage; archiving

Greater capacity; Longer lasting than other forms of optical media

Expensive; not compatible with most DVD players

Blu Ray Largest capacity

Video games, data, HD movies, camcorders

Highest access speeds and data transfer rates

Expensive

DO NOW IN COPYBOOK

What is the difference between backing storage and main memory?

Solid State Backing Storage Memory Stick/Pen Drive/USB Drive Storage medium and device are the same Can store up to 64 GB of data Used to transport files and backup data

from computer to computer Advantages

More compact than equivalent optical or magnetic media; very portable

More robust than other forms of memory, even surviving being “washed”

Disadvantages More expensive per GB than hard disk

drives

Solid State Backing Storage Flash Memory Cards Can store up to 64 GB of data Used for storing photographs in digital

cameras Used in mobile phones to store phone

numbers, photographs, etc. Used in MP3 players to store music

Advantages More compact than equivalent

optical or magnetic media

Disadvantages More expensive per GB than hard disk drives; can

only be used for a particular number of read/write operations Have lower storage capacity than hard disk drives