How We Measure Memory

Learning Goal

Today we are going to learn how the computer stores information.

At the Bottom of things

• A piece of digital information is always stored as a sequence of binary states.

What is a “binary state”???

A microscopic view of a CD

Electrical Memory

• RAM, Memory Sticks, Memory Cards all store information as sequences of negative or neutral charges.

• The two states are negative and Neutral

A “bit”

A bit of information is a single binary state.

For example:

• “on” or “off”

• “pit” or “land”

• “negative” or “neutral”

• “dead or “alive”

“A Byte”

There are 8 bits in a byte.

A byte can hold a single character. Ex: ‘A’

A “Kilobyte” (Kb)

A Kilobyte is 1024 bytes or 210. (or about 1000 bytes)

You would measure an Email in Kb.

A Megabyte Mb

A megabyte is 1 048 576 bytes which is 220. (Or about 1 million Bytes)

Mp3s and digital pictures are usually 2-5 Mbs.

Gigabytes (Gb)

A Gigabyte is 1 073 741 824 bytes or 230 or about 1 billion bytes.

We measure RAM, Hard drives, Memory cards in Gb.

Terabyte

• A Terabyte is 240 which is 1 099 511 627 776 bytes

Large hard drives are measured in Terabytes.

Beyond Terabytes??

Chart from Wikipedia.

Summary1.A bit is a single binary state.

2.There are 8 bits in a byte

3.There are about 1 000 bytes in a Kilobyte.

4.There are about 1 000 Kilobytes in a Megabyte

5.There are about 1 000 Megabytes in a Gigabyte

6.There are about 1 000 Gigabytes in a Terabyte