M. GuymonPleasant Grove High School

Spring 2003

RAM vs. ROM

RAM “Random Access

Memory” The ability of a storage

device to go directly to a specific storage location without having to search sequentially from a beginning location.

Very volatile• Cannot hold data when

the power is off.• Looses all data when

power is lost.

ROM “Read only memory” Drives can read data

from disks, but cannot store new data on them.

One or more integrated circuits that contain permanent instructions that the computer uses during the boot process.

M. GuymonPleasant Grove High School

Spring 2003

Binary Number System

A method for representing letters or numbers using only two digits, 0 and 1. Bit

• Each 0 or 1 Byte

• 8 bits

Also referred to as Base 2 Binary Code.

M. GuymonPleasant Grove High School

Spring 2003

Memory Measurements

Bit Each 0 or 1

Byte 8 bits

Kilobyte Approximately 1,000 bytes Exactly 1,024 bytes

Megabyte Approximately 1 million

bytes Exactly 1,048,576 bytes

Gigabyte Approximately 1 billion

bytes Terabyte

Approximately 1 trillion bytes

M. GuymonPleasant Grove High School

Spring 2003

Storage Devices

Used to keep data when the power to the computer is turned off.

Medium/media Location where data is stored.

M. GuymonPleasant Grove High School

Spring 2003

Hard Disk

Usually mounted inside the computer’s system unit.

Can store billions of characters of data. Stated in forms of

bytes:• Megabytes or

Gigabytes

M. GuymonPleasant Grove High School

Spring 2003

Magnetic Storage

Recording of data onto disks or tape by magnetizing particles of an oxide based surface coating.

A fairly permanent type of storage that can be modified.

M. GuymonPleasant Grove High School

Spring 2003

Floppy Disk

Round piece of flexible Mylar plastic covered with a thin layer of magnetic oxide and sealed inside a protective covering.

May be referred to as a “floppy”

3½ disk capacity is 1.44 MB or 1,440,000 bytes

M. GuymonPleasant Grove High School

Spring 2003

Floppy Disk Options

FormattedPreparing the disk for use by the

computer. Write-protected

Setting the disk so that it can not be written to by the computer.

M. GuymonPleasant Grove High School

Spring 2003

Zip Disk

Floppy disk technology manufactured by Iomega. Available in 100 MB and 250 MB versions

M. GuymonPleasant Grove High School

Spring 2003

Digital Audio Tape

Method of storing large amounts of data on tape using helical scan technology to write data at high densities across the tape at an angle.

M. GuymonPleasant Grove High School

Spring 2003

Optical Storage

Means of recording data as light and dark spots on CD or DVD.

Reading is done through a low-power laser light.Pits

• Dark spots

Lands• Lighter, non-spotted surface areas

M. GuymonPleasant Grove High School

Spring 2003

CD-ROM

“CD – Read Only Memory” Also called CD-R

CD-Read Storage device that uses

laser technology to read data that is permanently stored on compact disks, cannot be used to write data to a disk.

M. GuymonPleasant Grove High School

Spring 2003

CD-RW

“CD-Read Write” A storage device that reads data from CD’s and also

can write data to CD’s. Similar to a CD-ROM, but has the ability to write to

CD.

M. GuymonPleasant Grove High School

Spring 2003

DVD-ROM

“Digital Video Disks – Read Only Memory”

Reads data from CD’s (audio and data) and DVD’s (data or movie)

Cannot be used to write data to a disk.

M. GuymonPleasant Grove High School

Spring 2003

Resources

Parsons, June Jamrich, and Dan Oja. Computer Concepts. Boston: Course Technology - Thompson Learning, 2002.