Computer Logic
Distinction between analogue and discrete processes and
quantities. Conversion of analogue quantities to digital
form. Using sampling techniques. Storage units.
Digital Data
Digital data is represented by 1s and
0s
 1 represents that the switch is on
 0 represents that the switch is off

Digital data (1s and 0s) is known as
binary.
 A computer system only understands
digital data

Analogue Data

Analogue data is represented by
analogue signals

An example of analogue data are sound
waves from our voice
Analogue data must be
converted to digital data for
the computer to understand it.

Analogue to Digital Data
ATD
As we said before analogue signals
need to be changed to digital data to
be understood by our computer.
 ATD devices convert analogue signals to
digital data

Digital Data to Analogue Signals
DTA
For us to understand computer language
the digital data needs to be
converted to analogue data
 DTA devices convert
digital data to analogue
signals, ex: modem

1001
0010
Dear
John,Is it
OK if we
meet at
6?
IS
P
Dear John,
Is it OK if
we meet
at 6?
1001
0101
Comparing Analogue to Digital
devices
Analogue device




Continuous signal
Varying values
Values not rounded up
Difficult for precise reading
Digital device




Not a continuous signal
Values rounded up
Easy and clear to read
Becoming more precise
Analogue and Digital Graphs
Analogue graph
Digital graph
Changing an Analogue graph to a Digital graph is called Sampling
Units of Storage
A computer has many different units of
storage
 The storage units we will be going through
today are;








Bits
Bytes
Kilobytes
Megabytes
Gigabytes
Terabyte s
Each storage unit is made up of a number of
bits
Bit

A bit is the smallest unit of storage within
a computer

A bit can only store a 1 or a 0

A bit is too small to store anything, hence
they are joined to create other larger
storage units.
1 Bit
Byte

A byte is made up of 8 bits

One character is made up of 8 bits, hence
1 byte can hold 1 character.

To store the word byte you would need
4 bytes
8 Bits
1 Byte
Kilobytes

Bytes are still very small to store many
files so a larger storage unit is used, a
Kilobyte

1024 bytes are grouped together to
create a kilobyte
1024
Bytes
1
KiloByte
Units of Storage
Unit
Equivalent
Bit
(Can only store 0 or 1)
Byte
8 Bits
Kilobyte (KB)
1024 Bytes
Megabyte (MB)
1024 Kilobytes
Gigabyte (GB)
1024 Megabytes
Terabyte (TB)
1024 Gigabytes
Converting Units of Storage

In order to convert small units to large
ones we need to divide

If we want to convert 7680 Bytes into KB
(smaller to bigger unit);
1 KB = 1024 Bytes
? KB = 7680 Bytes
7680/1024=7.5KB
Converting Units of Storage

In order to convert large units to smaller
ones we need to multiply

If we want to convert 3MB into KB
(bigger to smaller unit)
1 MB = 1024 KB
3 MB = ? KB
3 x 1024 = 3072 KB
More examples to work out

Convert 4MB into kB

Convert 5890 Bytes into KB

Convert 2GB into KB
(round up your answers when needed. eg;
4.6 becomes 4)
Answers

Convert 4MB into kB
MB = 1024 KB
4MB = ? KB
4 x 1024 = 4096MB
Answers

Convert 5890 Bytes into KB
1024 bytes = 1 KB
5890 bytes = ? KB
5890/1024 = 6KB
Answers

Convert 2GB into KB
1 GB = 1024 MB
2 GB = ? MB
2 x 1024 = 2048MB
1 MB = 1024 KB
2048MB = ? KB
2048 x 1024 = 2097152KB
If I want to know how many bytes there are
in 2GB what would my next step be?
Some typical storage devices
Device
Storage
Other
Possibilities
Floppy Disk
1.44MB
CD
700MB
DVD
4.7GB
8.7GB, 9.4GB
Pen Drive
8GB
2GB,
4GB,
16GB, 32GB
Blu Ray
25GB
50GB, 100GB
Hard Disk
500GB
1TB
Home – Work
 Handout
02
(form3opt1.blogspot.com)