ROM Organization of Microcontroller 8051 | ROM Memory of 8051 | 8051 Memory Organization
Summary
TLDRThis video lecture delves into the ROM organization of the 8051 microcontroller, explaining its internal 4KB ROM and the capacity to interface with an additional 64KB of external ROM. It clarifies the Harvard architecture, distinguishing between non-volatile program memory (ROM) and volatile data memory (RAM), essential for various embedded applications. The video also discusses how to utilize the EA^ bar pin for selecting between internal and external ROM, emphasizing the flexibility of memory management in the 8051 microcontroller.
Takeaways
- 😀 The 8051 microcontroller has a built-in 4 KB ROM and can interface with an additional 64 KB of external ROM.
- 🔍 The 8051 microcontroller features 128 bytes of internal RAM and can interface with up to 64 KB of external RAM.
- 🏛️ The 8051 follows the Harvard architecture, which means it has separate memory spaces for program and data.
- 📝 Program memory in ROM is non-volatile and fixed, while data memory in RAM is volatile and can change based on the application.
- 🔑 The EA/VPP pin determines the use of internal ROM; setting it to logic one indicates the use of the internal 4 KB ROM.
- 📍 The internal ROM has a fixed address range from 0x0000 to 0x0FFF in hexadecimal.
- 🌐 When using both internal and external ROM, the external ROM can be up to 64 KB and starts from address 0x1000 onwards.
- 🔄 The external ROM's address range can be determined by the programmer and can go up to 0xFFFF in hexadecimal.
- 🛠️ The 8051 is used in various embedded applications such as remote controls, microwave ovens, and washing machine timing controls.
- 📌 Fixed data like ASCII codes and seven-segment display data are stored in ROM because they are non-volatile and do not change.
- 🔄 Data that changes during program execution, such as temperature or time data, is stored in RAM as it is volatile.
Q & A
What is the ROM organization of the microcontroller 8051?
-The microcontroller 8051 has an internal ROM of 4 KB and can interface externally with up to 64 KB of ROM.
What is the size of the internal RAM in the 8051 microcontroller?
-The internal RAM of the 8051 microcontroller is 128 bytes in size.
How much external RAM can be interfaced with the 8051 microcontroller?
-Up to 64 KB of external RAM can be interfaced with the 8051 microcontroller.
What is the Harvard architecture, as it relates to the 8051 microcontroller?
-The Harvard architecture used by the 8051 microcontroller means it has separate program memory (ROM) and data memory (RAM), with program memory being non-volatile and data memory being volatile.
Why is the program memory in the 8051 considered non-volatile?
-The program memory is non-volatile because the program instructions are fixed and do not change, unlike data which can vary with different applications and is stored in volatile RAM.
What is the significance of the EA/VPP pin in the context of the 8051 microcontroller's ROM usage?
-The EA/VPP pin determines whether the 8051 microcontroller uses its internal ROM. When set to logic one (connected to VCC), it indicates the use of internal ROM. If set to zero, it signifies the use of only external ROM.
What happens when the EA/VPP pin is not connected to VCC in the 8051 microcontroller?
-If the EA/VPP pin is not connected to VCC (set to zero), the 8051 microcontroller will not use its internal ROM and will rely solely on external ROM.
What is the default address range of the internal ROM in the 8051 microcontroller?
-The default address range of the internal ROM in the 8051 microcontroller is from 0000h to 0FFFh.
Can the 8051 microcontroller use both internal and external ROMs simultaneously?
-Yes, the 8051 microcontroller can use both internal and external ROMs, but the internal ROM must be enabled by setting the EA/VPP pin to logic one.
Why might a programmer choose to use only external ROM in the 8051 microcontroller?
-A programmer might choose to use only external ROM if they require more memory than the internal 4 KB ROM provides, or if they need a specific size of ROM that is not available as a single IC, such as 60 KB.
What is the maximum size of external ROM that can be interfaced with the 8051 microcontroller?
-The maximum size of external ROM that can be interfaced with the 8051 microcontroller is 64 KB.
Outlines
📚 Introduction to Microcontroller 8051 ROM Organization
This paragraph introduces the topic of the video lecture series on the microcontroller 8051, focusing on its ROM organization. It explains that the 8051 microcontroller has an internal ROM of 4 KB, with the capability to interface externally with up to 64 KB of ROM. The speaker emphasizes the importance of understanding the memory organization within the 8051 and outlines the basic categories of memory: internal ROM, external ROM, internal RAM, and external RAM. The paragraph also introduces the Harvard architecture of the 8051, distinguishing between non-volatile program memory (ROM) and volatile data memory (RAM), and gives examples of applications where the 8051 is used, such as in remote controls and microwave ovens, to illustrate the concept of fixed programs and changing data.
🔍 Deep Dive into 8051 ROM Architecture and External Memory Interfacing
The second paragraph delves deeper into the ROM architecture of the 8051 microcontroller, explaining how to interface with external memory and the role of the EA/VPP pin in determining whether to use internal ROM. It details the default address range for internal ROM and how to extend this with external ROM, which can go up to 64 KB. The paragraph clarifies the use of the EA/VPP pin: setting it to logic one indicates the use of internal ROM, while setting it to zero signifies reliance solely on external ROM. It also addresses the practicality of ROM sizes available in the market, explaining why one might choose to use both internal and external ROMs, and the flexibility this provides in designing embedded systems with the 8051 microcontroller. The speaker invites any students with questions to post them in the comment box for further clarification.
Mindmap
Keywords
💡Microcontroller 8051
💡ROM Organization
💡Internal ROM
💡External ROM
💡Internal RAM
💡External RAM
💡Harvard Architecture
💡EA/VPP Pin
💡Non-Volatile Memory
💡Volatile Memory
💡Embedded Applications
Highlights
Introduction to the ROM organization of the microcontroller 8051.
The 8051 microcontroller has an internal ROM of 4 KB and supports interfacing with an external ROM of up to 64 KB.
Understanding the memory organization within the 8051 microcontroller is essential for students.
8051 has four different categories of memory: internal ROM, external ROM, internal RAM, and external RAM.
The 8051 microcontroller follows the Harvard architecture, separating program and data memory.
Program memory in ROM is non-volatile, while data memory in RAM is volatile.
The reason for the use of volatile data memory is the changing nature of data in various applications.
8051 is used in many embedded applications such as remote controls, microwave ovens, and washing machine timing controls.
Program stored in ROM is fixed and does not change, unlike data stored in RAM which may vary with application.
Fixed data such as ASCII codes and seven-segment display data is stored in ROM due to its non-volatile nature.
The EA/VPP pin configuration determines the use of internal ROM in the 8051 microcontroller.
When using only external ROM, the EA/VPP pin should be set to 0, and the external ROM can have a maximum size of 64 KB.
The internal ROM has a fixed address range from 0000h to FFFFh when EA/VPP is set to 1.
When interfacing external ROM, the address range can be decided by the programmer, starting from 1000h to FFFFh.
The flexibility of the 8051 microcontroller allows for the use of internal ROM, external ROM, or a combination of both.
The video offers to help clarify any confusion regarding ROM architecture in the 8051 microcontroller.
Transcripts
welcome to engineering funda family this
video is a part of microcontroller 8051
video lecture series and in this video
i'll be going to explain you
rom organization of microcontroller 8051
my dear students there are few basic
things that you should understand
see
the single chip of microcontroller 8051
that is having 4 kb of rom
but
here we can interface
externally 64 kb of rom
and whenever you interface external
memory
at that time there are few things that
you need to keep in your mind that is
what i'll be explaining you in this
video
but before that you should understand
how memory organization is there inside
microcontroller 8051 so all the basics
regarding memory that i'll be explaining
you in this video step by step so let us
see all those things one by one so here
my dear students
first of all you should understand that
8051
that is having four different categories
of memories
here
internal rom is there which is having
size of 4 kb with 8 0 5 1
as well as externally we can interface
64 kb of rom with 8051
and
8051 that is having internal ram of size
of 128 bytes
here my dear students externally we can
interface
64 kb of ram with 8051 so in total there
can be four different categories of
memories
these two memories internal memories
that is already there with eight zero
five one but as if programmer is having
need of some extra memory then
programmer can
interface external ram and rom with
eight zero five one
here few more things that you need to
understand like architecture of 8051
microcontroller
8051 microcontroller follows harvard
architecture howard architecture means
what howard architecture means here we
have separate program memory and
separate data memory
obviously program memory which will be
having instructions that we will be
having with rom it should be
non-volatile
while data memory that will be there
with ram that could be volatile
let me try to explain you why it is like
this the reason is
see whatever program that we have for
this microcontroller that should be
fixed right it will never change it will
just execute instructions one by one
but data may change so in various
applications you will be having
different data so you may need to change
the data with respect to execution of
program that's why
data will be volatile that will be
storing inside ram
let me explain you further how things
are there with eight zero five one so
when we talk about applications then you
should know eight zero one that we use
it with many embedded applications those
applications may be remote control it
may be there based on microwave own it
may be there with washing machine timing
control so likewise there are many
embedded applications which is
practically available with eight zero
five one microcontroller
here my dear students
when you use eight zero five one in
application at a time you should
understand few basic things like
whatever program that we store inside
memory that should be fixed right you
cannot change program so that will be
there inside rom
but data may change with respect to
application that will be temporarily
stored inside memory that's why it
should be there with ram
like for example
when you store temperature as a data
obviously data will change like for
example you are having
ac in which you are storing one program
so your program is based on
temperature should not exceeds to
25 degree celsius right that is what
your program
so that program will be there inside rom
but
temperature data that will change
as cooling is happening your temperature
will go down
right and it should not exit to 25
degree celsius so that data of
temperature that will there inside ram
so harvard architecture is used with
8051 in which
program will be stored inside rom
and data will be stored inside ram
here my dear students some fixed data
like ascii code
right like data of seven segment display
that we will be storing inside rom as it
should be non-volatile right it will be
fixed but the data which we use it in
program
like temperature data time data so those
data will be changing right so that's
why we will be storing that inside ram
so in short my dear students eight zero
five one that is based on howard
architecture it will be having ram as
well as rom rom will be used for program
ram will be used for data here
internal ram and rom is available
internal ram is having size of 128 byte
internal rom is having size of 4 kb but
as if programmer is having some high end
application then programmer can
interface external memory like ram and
rom and at max we can interface 64 kb of
rom and ram now i'll explain you how
rom architecture is there with eight
zero five one
so here my dear students when
only we use internal rom at that time
it should be very clear to you first of
all you will have to make
e a bar terminal is equals to 1.
see with 8 0 5 1 this pin is playing
essential rule it explains you whether
we use internal rom or not
as if you use internal rom then you'll
have to make sure this pin that should
be connected with vcc means it is logic
one whenever you make this pin is equals
to logic one you are using internal rom
here as if programmer is not interfacing
external memory then only internal rom
will be available and that address will
start from zero zero zero zero hex to 0
f f f hex
that is by default address of this
internal rom where programmer can store
their program
here few more cases are there like as a
programmer needs to have some extra
memory
then obviously programmer will be using
internal as well as external rom
and
in case of programmer is using internal
rom then ea bar that must be equals to
one what it indicates internal rom is
there with size of 4 kb and it will be
having address ranging from 0 0 0 0 hash
to 0 f f f hex means this address is
allocated with internal rom
now
here as programmer is having need of
some more memory external rom is
available right but at max you can have
64 kb means 60 kb of external rom can be
interfaced so from here onwards only you
can use addresses so next address after
this 0 f x that will be 1 0 0 0
hex right
here my dear students
after that it can go up to maximum
ffff hacks right so this will be the
available range for external rom
and here my dear students ea bar
explains whether we use internal rom or
not here sometimes
you may be having only external rom
so in that case you will have to keep ea
bar is equals to zero what it means
eight zero five one will not use
internal rom so in that case external
rom that can be having maximum size of
64 kb it will be starting from 0 0 0 0
hex to up
ffff hex
address right now few of my students who
have been asking me some questions like
they have been telling me sir
if you use only external rom then what
is the use of internal rom so obviously
here programmer is deciding this right
let me tell you one more thing like for
example when you have external rom only
at the time you are discarding internal
rom why the reason is my dear students
when you go in market you don't have
external rom with the size of 60 kb
right
either you
buy a rom with size of 32 kb
or you can buy a rom with the size of 64
kb
so you cannot have 60 kb of rom for that
you'll have to use multiple roms right
so here external rom that we are using
with 64 kb
or 32 kb you don't have facility of 60
kb of rom for that you have to use
multiple ics that is why
8051 is having this facility in which
you can have internal as well as
external as well as only external rom
facility but here remember when you keep
ea bar is equals to 1 your internal rom
will be there in use and it will be
having fixed address you cannot change
this address right
only thing is external rom that can be
having different address that can be
decided by programmer so this is how
structure is there in terms of rom i
hope it is clear to you still if any
confusion is there just post that in
comment box i'll be happy to help you
thank you so much for watching this
video
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