Introduction to Memory
Summary
TLDRThis video session delves into computer memory, comparing it to the brain's faculty for encoding, storing, and retrieving information. It highlights the importance of memory size, access time, and the processor's speed, explaining the concept of gigahertz processors and how they relate to nanosecond operations. The session introduces primary and secondary memory, detailing RAM as volatile and dynamic, and contrasting it with the faster, albeit more expensive, cache memory. It also touches on secondary memory's permanence and larger capacity, using the hard disk drive as an example of its slower access time. The video concludes by emphasizing the organized use of various storage units in computer architecture.
Takeaways
- 🧠 Memory in computers is analogous to human memory, storing encoded data and instructions for quick retrieval.
- 💾 Computers use bits to represent stored information, with each memory cell holding a binary value of 0 or 1.
- ⏱️ Processors are incredibly fast, with speeds measured in gigahertz, leading to nanosecond task execution times.
- 🔢 The time calculation for a 2 GHz processor is derived from the frequency, resulting in a task execution time of half a nanosecond.
- 🚀 The speed of memory is crucial for efficient computing, as a slower memory can cause the fast processor to idle.
- 💻 Primary memory, or RAM, is used for immediate tasks and is randomly accessible, unlike secondary memory which is more permanent storage.
- 🔌 RAM is dynamic, requiring periodic recharging to retain its binary state, which makes it slower than modern processors.
- 🏎️ Cache memory, made of static RAM, is faster than main memory but more expensive, serving as a quick-access storage for frequently used data.
- 🗄️ Secondary memory is slower but non-volatile, retaining data even when power is off, and is cheaper and larger in capacity than main memory.
- 💿 Hard disk drives exemplify the slower access times of secondary memory due to semi-random access patterns requiring sequential data block movement.
- 🔄 The organization of memory in a computer system, including registers, cache, main memory, and secondary storage, is essential for balancing speed and permanence.
Q & A
What is the primary role of memory in both the human brain and computers?
-Memory in the human brain and computers is responsible for encoding, storing, and retrieving data or information when needed.
How is data represented in computer memory?
-In computer memory, data is encoded as bits, with each memory cell having a value of either zero or one.
Why isn't a single large memory unit the best solution for computer memory?
-A single large memory unit is not ideal because as the size of the memory increases, the time to access the data also increases, which can slow down the processor.
What is the frequency of a 2 gigahertz processor, and how does it relate to time?
-A 2 gigahertz processor has a frequency of 2 billion cycles per second. The time for one cycle is calculated as 1 divided by the frequency, which equals 1 nanosecond for a 2 GHz processor.
Why is it important for memory to be fast in relation to the processor's speed?
-Memory needs to be fast to keep up with the processor's speed; otherwise, the processor will remain idle most of the time, leading to an inefficient machine.
What are the two main types of memory in a computer system?
-The two main types of memory are primary memory, used for immediate tasks, and secondary memory, used for more permanent storage.
What is Random Access Memory (RAM), and why is it called 'random access'?
-Random Access Memory (RAM) is the primary memory where data can be accessed in any order, hence the term 'random access,' making it efficient for quick data retrieval.
What is the difference between Dynamic RAM (DRAM) and Static RAM (SRAM)?
-Dynamic RAM (DRAM) uses transistors with associated capacitors that need periodic recharging to retain data, while Static RAM (SRAM) does not have capacitors and is faster but more costly.
Why are secondary memory devices slower than primary memory?
-Secondary memory devices are slower because they are designed for permanent data storage and are larger in capacity, making them more cost-effective but with slower access times compared to primary memory.
How does a hard disk drive (HDD) differ from main memory in terms of data access?
-A hard disk drive has semi-random access because while tracks can be accessed randomly, accessing specific data blocks within those tracks requires sequential movement, making HDDs slower than main memory.
What is the role of the operating system in managing memory and storage?
-The operating system manages the space within primary memory, moves data between primary and secondary storage, and performs tasks such as paging or demand paging to ensure efficient use of memory resources.
Outlines
🧠 Understanding Memory in Computer Organization
This paragraph introduces the concept of memory in computer organization and architecture, drawing an analogy between human memory and computer memory. It explains that computer memory, also known as 'store,' is essential for storing various types of data as bits, which are processed by the computer's processor. The paragraph highlights the limitations of a single large memory unit due to increased access time with size and the importance of speed in memory access, especially considering the high-speed processors available today. It also touches on the concept of primary and secondary memory, with primary memory being used for immediate tasks and secondary memory for more permanent storage, and introduces the idea of Random Access Memory (RAM) and its dynamic nature.
💾 Exploring Memory Hierarchy and Storage Devices
The second paragraph delves into the hierarchy of memory storage, starting with the processor's registers, which have limited storage capacity, and moving on to the main memory and cache for faster access to frequently used data. It uses the analogy of keeping a phone in a pocket for easy access to explain the purpose of cache memory. The paragraph also discusses the communication between main memory and cache through data blocks and cache memory mapping, which will be covered in more detail in future sessions. It contrasts volatile memory, which loses data when power is off, with non-volatile secondary memory that retains data permanently. The paragraph concludes with an example of a hard disk drive, explaining its slower speed due to semi-random access, and touches on virtual memory mapping and paging, which are managed by the operating system without the processor's awareness.
Mindmap
Keywords
💡Memory
💡Processor
💡Bits
💡Primary Memory
💡Secondary Memory
💡Cache
💡Volatile
💡Non-Volatile Storage
💡Hard Disk Drive (HDD)
💡Cache Memory Mapping
💡Paging
Highlights
Introduction to the session focusing on memory in computer organization and architecture.
Memory's role in encoding, storing, and retrieving data in both the human brain and computers.
Memory cells in computers store data as bits, with each cell having a value of 0 or 1.
The challenge of increasing access time with the size of memory and the fast speed of processors.
Explanation of processor frequency and its relation to time, using the example of a 2 GHz processor.
The concept of primary memory for immediate tasks and secondary memory for permanent storage.
Random Access Memory (RAM) as the primary memory, allowing any order access due to its dynamic nature.
Dynamic RAM requires periodic recharging to retain binary bits due to its capacitors.
The introduction of cache memory made of Static RAM, which is faster but more costly than main memory.
Cache memory's role in speeding up processor performance by storing frequently accessed data.
Volatile nature of main memory and cache, losing data when power is off.
Secondary memory's role in permanent data storage, despite being slower and larger than main memory.
Hard disk drives as an example of secondary storage, explaining their slower access time due to semi-random access.
The processor's unawareness of secondary memory and the operating system's role in managing memory.
The importance of memory hierarchy and the organized use of different storage units for efficiency.
Upcoming session details on delving deeper into memory storages and the memory hierarchy.
Conclusion emphasizing the importance of an organized memory system rather than a single large memory.
Transcripts
hello everyone
welcome back to this wonderful journey
of computer organization
and architecture in this session we will
be focusing on memory
so let's get to learning wikipedia
states
memory is the faculty of brain by which
data or
information is encoded stored and
retrieved
when needed similarly in case of
computers
memory which was initially termed as
store plays a similar role
everything be it an image an audio file
a text file or instructions for a key
press
or a mouse click if that is stored in
the computer memory
it's actually encoded as bits basically
each memory cell can have either zero or
one
and all these are comprised of millions
of
bits and processed by the processor the
brain of the computer
so we might think that having a single
large memory unit
is the solution to the situation but i'm
afraid
it's not with the increasing size of the
memory
the time to access them gets increased
and
time is the essence here let me put it
to you this way
we know the processor is very fast i
mean today we have gigahertz processors
even in our smartphones
suppose we have 2 gigahertz processor
this means
the frequency is 2 gigahertz hence time
is
1 upon frequency that is 1 by 2 into 10
to the power 9.
now how did i get this 10 to the power 9
let's have a chart
shall we we know one kilo unit equals to
1000 units hence 10 cube units
therefore one mega unit is 1 000 kilo
units and thus
10 to the power 6 units and finally 1
giga
units is 1 000 mega units and thus 10 to
the power 9 units
now coming back to our initial
illustration 1 upon 2 into 10 to the
power 9
seconds equals to 1 by 2 into 10 to the
power minus 9 seconds
and 10 to the power minus 9 seconds is 1
nanosecond
therefore in half a nanosecond our
processor can perform a single task
so to conclude the cpu is fast not
only fast real fast and keeping up with
this kind of speed
is tough because if our memory device is
way slower than the cpu
then the cpu will remain idle for the
most of the time and we won't have an
efficient machine also not only the
speed
the size and the cost are considered to
when it comes to memory that's why we
have various memory devices
associated to our computer computer
designers termed the memory to perform
immediate tasks as
primary memory and the memory which is
used as a more permanent storage
is known as secondary memory when we
play an audio file our system manager
that is the operating system manages the
space within the primary memory
to perform the instructions which is
understanding the mouse click
opening up the default application for
playing the file
after bringing it from the secondary
storage into the primary memory
now as because we need the execution of
the instructions to be as
quick as possible the sales in the
primary memory can be accessed in any
order and that's why the name
random access memory or ram to be
precise
it's actually dynamic ram because in
each memory chip
there is a transistor with which a
capacitor is associated
the transistors can retain the binary
bit as long as the associated capacitors
have charge
so periodic recharging is needed for
value retention and that's why it's
called dynamic but it's still slow for
the modern day processors
so we opt for another fast memory
storage
the cache now the cache is made up of
static ram which doesn't have any
capacitors
but they are very costly in comparison
to the main
or primary memory however cache happens
to be the fastest memory storage
among all others anyway all these
be that cache or main memory are
volatile
that means they can only retain the data
in them until the power is off
therefore to store the data more
permanently
we opt for the next type of memory
storage the
secondary memory now secondary memories
are slower than the main memory
yet they can retain data permanently
that is the data inside them are still
there
even if the power is off they are larger
in terms of capacity
also they are cheaper than the main
memory we will definitely get into the
detailed study of various types of
secondary memories
in our due course but for the time being
i would like to take an example
of one of the most popular secondary
storage devices that is the hard disk
drive
to explain one of the reasons why these
are slower compared to the main memory
for a hard disk drive the axis is
semi-random
now why is so because using this
red right head we can randomly get to
any of these
tracks but from there getting to the
particular block where the data is
stored
requires sequential movement so the time
to access
any data in the hard disk drive becomes
longer
naturally now let me show you the big
picture
we have the processor and it has got its
registers but these are not capable of
storing large amount of data
to be really honest they can barely
store a single instruction
so we opt for main memory yet main
memory is also slow for the processor
so we stored the frequently accessed
stuffs in a smaller
yet faster than main memory speed memory
storage
the cache it's like keeping our phones
in our pockets
instead of the backpack that we are
carrying because we tend to use the
phone very frequently
now the main memory and the cachet
communicates using data word or block
and the ways the communication takes
place is known as
cache memory mapping worry not we will
learn every type of these in details
later so having this organization
does speed things up a notch but none of
these
retain data permanently so we need a
permanent
non-volatile storage the secondary
memory
using the virtual memory mapping
technique the operating system lets the
main memory
and the auxiliary secondary storage
communicate with one another
using pages for this to happen the
operating system must be capable of
performing
paging or demand paging fun fact
the processor is aware of the presence
of the registers the caches
even the main memory but it has got no
clue
about the existence of the secondary
memory there
the operating system comes at rescue and
manages all the things
so to conclude having a single large
memory is not really a solution
instead we use different types of
storage units
in an organized fashion so
that was all for this session in the
next one we will get into the details of
these memory storages and learn about
the memory hierarchy
hope to see you in the next one thank
you all for watching
you
Weitere ähnliche Videos ansehen
Memory Hierarchy & Interfacing
Primary Memory : Types and differences from Secondary Storage Memory
[Part 1] Unit 3.3 - Memory Units
Basics of OS (Storage Structure)
BANA-AG_DISK SCHEDULING:DISK PERFORMANCE PARAMETERS
L-5.19: Virtual Memory | Page fault | Significance of virtual memory | Operating System
5.0 / 5 (0 votes)