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Contents 1 Measurement 2 Storage 2.1 External Memory 2.1.1 Floppy Disk 2.1.2 Compact Disks 2.1.3 Digital Video Disc 2.2 Internal Memory 2.2.1 ROM 2.2.2 FLASH 2.2.3 RAM

Measurement

A bit can have one of two states, 0 or 1, True or False. A byte is made up of 8 bits, it can have one of 256 states (2^8). A word is made up of any number of bits depending on the architecture. A single character takes one byte.

1000 bytes equal a kilobyte (kB)

1 000 000 bytes equal a megabyte (MB)

1 000 000 000 bytes equal a gigabyte (GB)

1 000 000 000 000 bytes equal a terrabyte (TB)

In many cases the number is rounded to the nearest power of two since powers of two are much simpler to handle in hardware. This is especially true on silicon where the layout is strictly two-dimensional.

Storage

There are many ways to store data.

External Memory

Floppy Disk

A magnetic storage device that can hold 1.44 MB. Simmaler to a cassete tape

Compact Disks

CD-R CD Recordable

CD-RW CD Rewriteable

CD-R can only be wrote on once the CD-RW can be rewrote as many times needed.

Digital Video Disc

DVD's are simmilar to CD's except the DVD has much higher storage capacity.

Internal Memory

ROM

Read only memory built into the computer cannot be erased. Hold information on how to bootup an settings.

FLASH

FLASH memory has replaced ROM in almost all applications. It is electrically erasable and programmable but more fragile.

RAM

Random access memory is not permanent without power but is very fast. RAM can be added in expansion slots.