Grade 8 Term 2

Topic: Storage

The relationship between bit and byte

In computer systems a byte is a binary unit of measurement used to refer to disk storage space in a hard disk drive or Random Access Memory (RAM) memory on computer systems.

It takes 8 Bits to create one Byte where a Bit is also a binary digit consisting of a value of 0 or 1. For example 10101010, 00000000, 11111111 are all 8 bits long and form 1 Byte. Put simply a Byte is a collection of Bits.

In Summary:

Bits are binary digits. A bit can hold the value 0 or 1.

Bytes are made up of 8 bits each.

Binary math works just like decimal math, but each bit can have a value of only 0 or 1.

Convert from Binary to Decimal

Convert from Decimal to Binary

To convert 95 to binary:

The digits are read from bottom up

Therefore the answer is:

95 written as binary  = 0 1 1 1 1 1

Adding Binary

  010

+ 111

  ---

 1001

Starting at the right, 0 + 1 = 1 for the first digit. No carrying there. You've got 1 + 1 = 10 for the second digit, so save the 0 and carry the 1. For the third digit, 0 + 1 + 1 = 10, so save the zero and carry the 1. For the last digit, 0 + 0 + 1 = 1. So the answer is 1001. If you translate everything over to decimal you can see it is correct: 2 + 7 = 9.

Subtopic: Primary Storage

Primary storage, also known as main storage or memory, is the main area in a computer in which data is stored for quick access by the computer's processor.

Random Access Memory (RAM)

Random-access memory (RAM) Alternatively referred to as main memory, primary memory, or system memory, Random Access Memory (RAM) is a computer storage location that allows information to be stored and accessed quickly from random locations within DRAM on a memory module. Because information is accessed randomly instead of sequentually like a CD or hard drive the computer is able to access the data much faster than it would if it was only reading the hard drive. However, unlike ROM and the hard drive RAM is a volatile memory and requires power in order to keep the data accesible, if power is lost all data contained in memory lost.

Read Only Memory (ROM)

ROM is "built-in" computer memory containing data that normally can only be read, not written to. ROM contains the programming that allows your computer to be "booted up" or regenerated each time you turn it on. Unlike a computer's random access memory (RAM), the data in ROM is not lost when the computer power is turned off. The ROM is sustained by a small long-life battery in your computer.

Subtopic: Secondary Storage

Secondary storage, sometimes called auxiliary storage, is all data storage that is not currently in a computer's primary storage or memory. An additional synonym is external storage.

In a personal computer, secondary storage typically consists of storage on the hard disk and on any removable media, if present, such as a CD or DVD.

Storage quiz

1. Which of the following best represents a byte?

a.       book

b.      10001001

c.       &&&&&

d.      12345678

2. A bit can be one of two values. What are they?
3. A bytes is normally represented by how many bit?
4. Add the following. 1101 + 0010 + 1100
5. What is 00001111 in decimal?
6. Show 63 in binary
7. What name is given to the area of the computer where data is stored for quick access by the processor?
8. Give another name for secondary storage.
9. List 5 secondary storage devices.
10. Order the following storage devices by capacity starting with the smallest capacity. Hard drive * DVD *diskette