[CSig] Data Storage

Data Storage

by Andy tsui

​Objectives

• ​Understand how data storage is measured

• ​Calculate the file size of an image file and a sound file, using information given

Storage units in computer​

• Computer represents information in Bits, however

• ​When storing data, we always use "Bytes" as smallest unit

​

​Note: Short form for Byte is "B" (capital B) while for bit is "b" (small letter")

Multiple Choice

1 Byte equals to how many bits?

• 2

• 4

• 6

• 8

SI and SI Binary Units

• 1024 or 2¹⁰ = Kibi

• 2²⁰ = Mibi or Mebi

• ​2³⁰ = Gibi

• ​2⁴⁰ = Tibi

• ​2⁵⁰ = Pebi

• ​2⁶⁰ = Exbi

• ​Note: each level is x1024 of the previous one

• ​i.e. 1024 Gibi = 1 Tibi

• 1000 or 10³ = kilo

• 10⁶ = mega

• ​10⁹ = Giga

• ​10¹² = Tera

• ​10¹⁵ = Peta

• ​10¹⁸ = Exa

• ​Note: each level is x1000 of the previous one

Multiple Choice

A hard disk drive is labelled as 500GB, how many Terabyte it has?

• 0.5TB

• 50TB

• 5TB

• 5000TB

​Fun facts

​Windows explorer reporting my hard drive is 476GB but on the label of my HDD is 512GB

​

​

Open Ended

Suggest why my 512GB HDD became 476GB only on Windows.

​Why 512GB became 476 only?

​Unit in transmission of data

• ​On the other hand, transmission speed of data is usually measured in "bps" or bits per second

​Calculating storage requirements

​Example 1:

​A 24-bit color image, with resolution 100 x 100 pixels, how much storage is required?

​

​

Multiple Choice

Calculate the storage requirements for a 100 x 10 8-bit image.

• 8 KB

• 800 KB

• 100 Bytes

• 800 Bytes

​Example 2

​A 2-minute stereo song, sampled at 16-bit, 20kHz. What is the storage requirements?

​

Multiple Choice

Calculate the storage requirements for a mono, 8-bit, 10kHz song, which is 30 seconds long.

• 300KB

• 30KB

• 2.4MB

• 240KB

​Conclusion

​Unit of storage and transmission

​Calculate the data size of image and audio