Differences between Primary and Secondary memory of a computer

Subject: 

COMPUTER     SCIENCE

Term:

FIRST TERM

Week:

WEEK 4

Class:

SS 2

Topic:

MEMORY UNIT

1. Memory Unit:(c) Differences between primary and secondary memory (d) Units of storage: Bits, Nibble, Bytes, Kilobytes (KB), Megabytes (MB), Gigabytes (GB) and Terabytes (TB) (e) Conversion from one unit to the other (f) Comparison of auxiliary Storage Devices under: Size, Speed, Technology (optical, magnetic and semiconductor)

Previous lesson: 

The pupils have previous knowledge of

COMPUTER MEMORY UNIT

that was taught as a topic in the previous lesson

 

Behavioural objectives:

At the end of the lesson, the learners will be able to

• say the Memory differences between primary and secondary memory
• Explain Units of storage of computer: Bits, Nibble, Bytes, Kilobytes (KB), Megabytes (MB), Gigabytes (GB) and Terabytes (TB)
• Understand the Conversion from one unit to the other
• Comparison of auxiliary Storage Devices under: Size, Speed, Technology (optical, magnetic and semiconductor)

 

Instructional Materials:

• Wall charts
• Pictures
• Related Online Video
• Flash Cards

 

[mediator_tech]

Methods of Teaching:

• Class Discussion
• Group Discussion
• Asking Questions
• Explanation
• Role Modelling
• Role Delegation

 

Reference Materials:

• Scheme of Work
• Online Information
• Textbooks
• Workbooks
• 9 Year Basic Education Curriculum
• Workbooks

 

WEEK 4

CLASS: SS 2

SUBJECT: COMPUTER SCIENCE

TOPIC: MEMORY UNIT (Cont’d) CONTENT:

Differences between Primary and Secondary memory

Units of Storage

Conversion from one unit to the other

Comparison of auxiliary storage devices

 

Sub-Topic 1: DIFFERENCES BETWEEN PRIMARY AND SECONDARY MEMORY

As earlier discussed, Computer memory can be categorized into primary and secondary memory. Both memories vary in speed, cost and capacity. The table below shows the clear differences between both memories;

PRIMARY MEMORY	SECONDARY MEMORY
It is considered as a main memory that is accessed directly by the computer	It is considered as an additional or additional memory not directly accessed by the CPU
The memory devices used for primary memory are semiconductor memories	The memory devices are magnetic and optical memories
These memories are also called internal memory	These memories are also called external memory
It is a type of temporary memory	It can be used as a permanent memory
The sizes of primary memory ranges between 512MB to 16GB RAMs	Secondary memories ranges between 80GB to 4TB Hard disk drives
It is directly accessed by the processor in a	It is not directly accessed by the processor,

 

random manner	input/output channels are used to access the secondary memory
It is embedded with two types of memory technologies – RAM and ROM	It is embedded in the form of mass storage devices like pen drive, CD, DVD, etc
It is classified as volatile (RAM) and non- volatile (ROM) in nature	It is generally non-volatile in nature
Data Processing speed is faster	Data Processing speed is somehow slow, not as fast as primary memory
It is costlier than the secondary memory devices	It is cheaper than primary memory
They are connected to the computer through ‘slots’	They are connected to the computer through drives and cables

 

EVALUATION:

Enumerate FIVE differences between Primary and Secondary memory

 

Sub-Topic 2: UNITS OF STORAGE

Data in a computer is represented or stored in a series of bits. Computer data storage provides one of the core functions of the modern computer, that of information retention. It is one of the fundamental components of all modern computers. We have various units of storage; they are as follows;

• Bit
• Nibble
• Byte
• Kilobyte (KB)
• Megabyte (MB)
• Gigabyte (GB)
• Terabyte (TB)
• Word

BIT:

This refers to the smallest basic unit of information that can be stored on a machine. A bit (binary digit) is the basic unit of information in computing and telecommunications. It exists in one of two possible distinct states (0 or 1). These may be the two stable states of a flip flop, two positions of an electrical switch, two distinct voltage or current levels allowed by a circuit, etc.

 

NIBBLE:

In computing, a nibble is a four-bit aggregation, or half a byte. The nibble is used to describe the amount of memory used to store a digit of a number stored in packed decimal within an IBM mainframe. This technique is used to make computations faster and debugging faster.

 

BYTE:

A byte is a unit of measurement of information storage that equals 8bits. It can be used to represent letters and numbers, for example, the number 01000001 is 8bits long and represents the letter A in ASCII. It is equivalent to 2nibbles. The size of computer memory is determined by bytes.

 

KILOBYTE (KB):

A kilobyte (KB) is a unit of data that equals 1024bytes. Although the prefix kilo- means 1000, the term

 

kilobyte and symbol have been used to refer to either 1024 (210) bytes in the fields of computer science and information technology.

 

MEGABYTE (MB):

A megabyte is 1024KB, that is, the kilobyte squared or 1024² bytes. The Megabyte is a multiple of the unit byte for digital information storage or transmission. It is commonly abbreviated as MB. GIGABYTE (GB):

A Gigabyte is a unit of data storage worth a billion bytes. It is equal to 1024 megabytes (1024³). The unit symbol for gigabyte is GB.

 

TERABYTE (TB):

A terabyte is equivalent to 1024 gigabytes (1024⁴) and is defined as about one trillion bytes. The prefix tera means 10 ¹² in the International System of Units, which equals 1,099,511,627,776 bytes

 

WORD:

A word represents 2bytes, which is equivalent to 16bits and 4nibbles.

 

EVALUATION

• State and write short notes on FIVE basic computer memory units
• State the relationship between;
  • Bit and byte
  • Kilobyte and Megabyte

 

Sub-Topic 3: CONVERSION FROM UNIT TO THE OTHER

To convert memory from one unit to the other is a simple conversion. For example, to convert MB to GB, simply divide the MB by 1024 and to convert back from GB to MB, multiply the GB by 1024. The process is the same for all units of memory. Worked examples are shown below;

Example I: Convert 16 bits to byte Relationship between units: 1byte = 8bits Therefore 16bits = 16/8 = 2bytes Example II: Convert 2bytes to bit

= 2 x 8 = 16bits

 

Example III: Convert 3KB to bytes

Relationship between units: 1KB = 1024bytes approximately 1000bytes Therefore   3KB = 3 X 1000 = 3000bytes

 

Example IV: Convert 100KB to MB

Relationship between units: 1MB = 1024KB approximately 1000Kbytes Therefore  100KB = 100/1000 = 0.1Mbytes

 

Example V: Convert 1.44MB to bytes

Relationship between units: 1MB = 1048576Bytes approximately 1000000bytes Therefore,         1.44MB = 1.44 x 1000000 = 1440000bytes

 

NOTE: Other examples should be practiced in class

 

EVALUATION

• Convert 1440000bytes to Megabyte
• Convert 1MB to Kilobyte

 

Sub-Topic 4:      COMPARISON OF AUXILIARY STORAGE DEVICES

The table below shows a summary of the various auxiliary storage devices based on certain characteristics;

DEVICE	SIZE	STORAGE	SPEED	TECHNOLOGY
Floppy Disk	Portable	Small      storage space	Slow speed	Magnetic tape technology
Hard Disk	Not as Portable as others	Enormous storage space	Slow as compared to main memory	Magnetic tape technology
Flash Drive	Portable	Large	Very high speed	Flash memory
Compact Disk	Portable	Large	High speed	Optical disk technology
Digital Versatile Disk	Portable	Extremely large storage	High speed	Optical disk technology

 

EVALUATION

Compare the following auxiliary devices in terms of size, speed, and technology

• Floppy Disk
• Hard Disk
• DVD

 

GENERAL EVALUATION

• Clearly distinguish between Primary and Secondary memory using the following criteria;

Speed, Accessibility, Cost, Size, and Mode of connection

• Highlight FIVE units of storage and their values (in bytes)
• Convert 5MB to KB
• State two auxiliary that uses optical technology

 

READING ASSIGNMENT

Study the topic ‘LOGIC CIRCUITS’ using your students’ textbook

 

WEEKEND ASSIGNMENT

1. Primary memory is embedded in two types of memory technology; …………. and ………….
   • RAM and ROM (b) Hard and Soft            (c) Input and Output       (d) None of the above
2. The…………………….. memory is generally non-volatile (a)RAM (b) ROM              (c) EEPROM       (d) DRAM

3. The primary memory are connected to the system through ……………….
   • Drives (b) Cables           (c) Wires             (d) Slots
4. Which of the following is not a unit of storage in computer?
   • Bytes (b) Megabytes                 (c) Kilobits          (d) Word
5. A Kilobyte is exactly ………………….. bytes and approximately…………………. Bytes

 

ESSAY QUESTIONS

1. Draw and Label a Floppy disk
2. Write short note on ‘Optical disk’

 

Primary memory is the short-term memory that we use to store information temporarily

How much can you remember? Most of us can hold about seven items in our short-term memory, give or take a few. But what exactly is short-term memory, and how does it differ from other types of memory? Short-term memory, also known as primary memory, is the memory we use to store information temporarily. It’s like a holding tank for the things we’re currently thinking about or working on. Unlike long-term memory, which can store enormous amounts of information for years (or even a lifetime), short-term memory is limited in both capacity and duration. The average person can only keep about four bits of information in their short-term memory for about 30 seconds. That’s not a lot of space! To put it into perspective, a bit is a binary digit (0 or 1). A byte is eight bits, and a megabyte is one million bytes. So if four bits equals one byte, then four bits would be able to store _____ in short-term memory. While the capacity of short-term memory may seem limited, it’s actually quite useful. When we’re trying to remember a phone number or an unfamiliar name, we’re using our short-term memory. And as long as we keep rehearsal (or repeating the information to ourselves), we can keep the information in our short-term memory for as long as we need it. So the next time you forget where you put your keys, just remember: it’s not you, it’s your short-term memory!

Secondary memory is the long-term memory that we use to store information permanently

CD, DVD, and other forms of secondary memory are used to store information permanently. Just like the primary memory in your computer, secondary memory is volatile, which means it needs power to maintain the stored data. However, CD, DVD, and other forms of secondary memory are non-volatile, meaning they don’t need power to maintain the stored data. The most common type of secondary memory is a hard disk drive (HDD). HDDs are made up of spinning disks that contain small magnetic particles that store data. SSDs are another type of secondary memory that are becoming more popular due to their faster data read/write speeds and lower power consumption.

Secondary memory can be accessed faster than primary memory, but primary memory is more responsive to stimuli

If you’re like most people, your primary memory is your go-to when you need to remember something quickly. After all, it’s right there in your head, and you can usually access it without too much effort. But what you may not realize is that your secondary memory can actually be accessed faster than your primary memory. That’s because your secondary memory is stored in a more organized way, making it easier for your brain to retrieve the information. However, there are some situations where primary memory is more responsive to stimuli. For example, if you’re trying to remember a name that you just heard, your primary memory is more likely to be successful than your secondary memory. So while secondary memory may be faster, it’s not always the best option.

Conclusion paragraph: So, what have we learned? Well, primary memory is the short-term memory that we use to store information temporarily. Secondary memory is the long-term memory that we use to store information permanently. The capacity of primary memory is limited, while secondary memory has an almost unlimited capacity. Primary memory can be easily lost if it’s not used regularly, while secondary memory is more permanent. Finally, secondary memory can be accessed faster than primary memory, but primary memory is more responsive to stimuli. If you remember all that (or even just skimmed over it), congratulations! You’re now a neuroscience expert!

 

Quiz On Differences between Primary and Secondary memory of a computer

[HDquiz quiz = “822”]