8085 Architecture | Learn Intel 8085 Microprocessor Architecture Step - By - Step
Summary
TLDRThis tutorial offers an in-depth exploration of the Intel 8085 microprocessor architecture, ideal for computer science students. It covers the 8085's history, technical specifications, and its five major functional units, including the memory unit, ALU, instruction decoder, timing and control unit, and interrupts. The video simplifies complex concepts, such as the instruction cycle and flag register, and explains the 8085's bus architecture, making it easier to grasp foundational microprocessor concepts.
Takeaways
- 😀 The Intel 8085 microprocessor was one of the first 8-bit processors launched by Intel in 1976 and remains in use today.
- 📚 Studying the 8085 architecture is fundamental for computer science students as it provides a basis for understanding more complex microprocessor architectures.
- 💡 The microprocessor's main function is to execute programs, which are sets of instructions directing the CPU to perform operations.
- 🔍 The instruction cycle of the CPU includes three steps: fetch, decode, and execute, which are repeated to perform program instructions.
- 🔧 The 8085 microprocessor architecture can be broken down into five major functional units: memory unit, ALU, instruction decoder, timing and control unit, and interrupts and serial communication unit.
- 🔢 The 8085 is an 8-bit processor with a 40-pin configuration, operating on a +5V supply and available in 3.5 MHz and 6 MHz execution speed variants.
- 📈 It has an 8-bit data bus and a 16-bit address bus, allowing it to address up to 64 kilobytes of memory.
- 🔑 The 8085 features 6 general-purpose 8-bit registers (B, C, D, E, H, L) and special-purpose registers for specific functions during instruction execution.
- 🚀 The accumulator, part of the ALU, is used to store operands and perform arithmetic and logical operations as per the decoded operation code.
- 📊 The flag register, or program status word (PSW), is an 8-bit register indicating the CPU status after ALU operations, using flags like carry, auxiliary carry, sign, parity, and zero.
- 🔄 The timing and control unit generates clock pulses and control signals to synchronize the operations of internal components and manage external hardware devices.
Q & A
What is the 8085 microprocessor and when was it launched by Intel?
-The 8085 microprocessor is an 8-bit processor launched by Intel Corporation in 1976. It was one of the first 8-bit processors and is still in use today in many devices.
Why is it important for computer science students to study the 8085 architecture?
-Studying the 8085 architecture is important for computer science students as it helps them understand foundational concepts necessary to study more complex microprocessor architectures and how CPUs work.
What is the basic operation of a CPU called?
-The basic operation of a CPU is called the instruction cycle, which includes fetch, decode, and execute operations.
What are the five major functional units of the 8085 microprocessor?
-The five major functional units of the 8085 microprocessor are the memory unit (register unit), the arithmetic and logic unit (ALU), the instruction decoder and machine cycle encoder unit, the timing and control unit, and the interrupts and serial communication unit.
What is the purpose of the Program Counter (PC) register in the 8085 architecture?
-The Program Counter (PC) register is a 16-bit special purpose register used to store the address of the instruction that needs to be fetched from memory.
What is the role of the Accumulator register in the 8085 processor?
-The Accumulator register is part of the Arithmetic and Logic Unit (ALU) and stores the operand part of the instruction format for performing arithmetic and logical operations.
What does the Flag Register indicate in the 8085 architecture?
-The Flag Register, also known as the Program Status Word (PSW), is an 8-bit special purpose register that indicates the status of the processor after each ALU operation, such as carry, sign, zero, auxiliary carry, and parity.
What are the functions of the Timing and Control Unit in the 8085 microprocessor?
-The Timing and Control Unit generates clock pulses and control signals to synchronize the operations of the CPU's internal components and manage the operations of various hardware devices connected to the system.
How many types of interrupts does the 8085 architecture support?
-The 8085 architecture supports eight software interrupts and five hardware interrupts.
What are the three main components of the 8085 bus architecture?
-The three main components of the 8085 bus architecture are the address bus, the data bus, and the control bus.
What is the significance of the data bus in the 8085 architecture?
-The data bus in the 8085 architecture is an 8-bit bi-directional bus used to transfer data between the CPU and the main memory RAM during memory read and write operations.
Outlines
📚 Introduction to Intel 8085 Microprocessor Architecture
This paragraph introduces the Intel 8085 microprocessor, one of the first 8-bit processors launched by Intel in 1976. It emphasizes the importance of studying the 8085 architecture for computer science students as foundational knowledge for understanding more complex architectures. The video tutorial aims to simplify the learning process by explaining the architecture, its functional components, and the interaction between these units. The microprocessor's role as the 'brain' of the computer system is highlighted, along with the basic operation of fetching, decoding, and executing instructions. The paragraph sets the stage for a detailed exploration of the 8085's architecture.
🔍 Detailed Exploration of 8085 Microprocessor Components
This paragraph delves into the technical features of the 8085 microprocessor, including its 8-bit data bus, 16-bit address bus, and 40 pins. It operates at 3.5 and 6 megahertz and has a stack pointer and six 8-bit general-purpose registers (B, C, D, E, H, L). The paragraph also discusses the processor's support for software and hardware interrupts. The focus then shifts to the five major functional units of the 8085: the memory or register unit, the arithmetic and logic unit (ALU), the instruction decoder and machine cycle encoder unit, the timing and control unit, and the interrupts and serial communication unit. Each unit's role in the microprocessor's operation is explained, providing a comprehensive overview of the 8085's internal workings.
🚀 Understanding CPU Registers and Their Functions
The third paragraph focuses on the various CPU registers within the 8085 microprocessor, explaining their types and functions. General-purpose registers are used for temporary data storage, while special-purpose registers serve specific functions. The program counter (PC), instruction register (IR), and accumulator are highlighted as key special-purpose registers. The accumulator is part of the ALU, which performs arithmetic and logical operations. The flag register, also known as the program status word (PSW), is detailed, explaining its role in indicating the CPU's status after ALU operations. The five flags used in the 8085 processor are the carry flag, auxiliary carry flag, sign flag, parity flag, and zero flag, which provide essential information about the results of operations.
🔌 The Role of Timing and Control Unit and Interrupts
This paragraph discusses the timing and control unit's role in synchronizing the CPU's operations through clock signals and control signals. It explains how these signals manage the execution of the instruction cycle and the interaction with hardware devices. The concept of interrupts is introduced, describing them as signals that pause the CPU's current activity to respond to external events. The paragraph outlines different types of interrupts supported by the 8085, including software, hardware, vector, non-vector, maskable, and non-maskable interrupts. The importance of interrupts in managing real-time events and their classification is emphasized.
🛠️ Bus Architecture and the 8085 Microprocessor's Communication
The final paragraph concludes the tutorial by discussing the 8085's bus architecture and how the microprocessor communicates with system hardware components. It describes the address bus, data bus, and control bus, explaining their functions in transferring addresses, data, and control signals. The address bus transfers 16-bit addresses between the CPU and main memory, the data bus facilitates 8-bit data transfer, and the control bus manages signals to hardware devices. The paragraph provides a complete understanding of the 8085's communication infrastructure, wrapping up the tutorial on the microprocessor's architecture.
Mindmap
Keywords
💡Intel 8085 Microprocessor
💡Microprocessor Architecture
💡Instruction Cycle
💡Arithmetic Logic Unit (ALU)
💡General Purpose Registers
💡Special Purpose Registers
💡Flag Register
💡Timing and Control Unit
💡Interrupts
💡Bus Architecture
Highlights
The 8085 microprocessor was one of the first 8-bit processors launched by Intel in 1976.
It was one of the most commercially successful processors and is still used in many devices.
Studying the 8085 architecture is fundamental for understanding more complex microprocessor architectures.
The microprocessor executes programs by fetching, decoding, and executing instructions in an instruction cycle.
Microprocessor architecture involves the design and layout of functional components and their interactions.
The 8085 microprocessor can be broken down into five major functional units for simplified study.
Technical features of the 8085 include an 8-bit processor with 40 pins, operating on a plus 5 volts supply.
It has variants with execution speeds of 3.5 and 6 megahertz and supports a 16-bit address bus.
The 8085 has a 16-bit program counter register and a 16-bit stack pointer for addressing memory.
It features 6 general-purpose 8-bit registers and can perform 16-bit operations by combining them into pairs.
The 8085 operates at 3.2 megahertz with a single-phase clock and supports multiple software and hardware interrupts.
The memory unit, also known as the register unit, is used for storing data, addresses, and machine instructions.
General-purpose registers are used for temporary data storage during program execution.
Special-purpose registers perform specific functions and some are accessible to programmers.
The program counter register (PC) stores the address of the next instruction to be fetched.
The instruction register (IR) holds the part of the instruction to be decoded.
The accumulator is part of the ALU and stores the operand for arithmetic and logical operations.
The flag register indicates the status of the processor after each ALU operation.
The timing and control unit generates clock pulses and control signals for synchronized operations.
Interrupts allow the microprocessor to pause current activity and respond to external events or peripheral device requests.
The 8085 supports eight software interrupts and five hardware interrupts, classified into various types.
The 8085 bus architecture includes an 8-bit data bus and a 16-bit address bus for data, address, and control signal transfer.
Transcripts
if you are looking for a complete guide
that will help you
understand the intel 808.5
microprocessor architecture
in the most simplified language then
this video tutorial is for you
in this video you will learn 808.5
architecture
its functional components and the
interaction between
various functional units step by step
let us start with a quick introduction
to 8085 microprocessor
the 8085 microprocessor was one of the
first 8-bit processor
launched by the intel corporation in
year 1976.
this was also one of the most
commercially successful processor
that is still being used in many devices
after the success of 808.5 processor the
intel
also launched many processors with
16-bit
32-bit and 64-bit architecture
however it is important for the students
of computer science
to first study the 808.5 architecture in
detail
this will help you understand some of
the most important
foundational concepts necessary to study
the microprocessor architecture
and how cpu works once you learn 808.5
architecture
then learning other complex architecture
will be much easier for you
welcome to learn computer
learncomputerscienceonline.com
and in this video we are going to
discuss intel 8085 microprocessor
architecture
in detail in this video you will learn
all the foundational concepts necessary
to understand
the intel 8085 microprocessor
architecture
its functional units and the technical
features
before we dive into our main topic it is
important to first understand
the functioning of the microprocessor
and how cpu works
the microprocessor is the brain of the
computer system
the main function of the microprocessor
is to execute the program
a computer program essentially consists
of
set of instructions that directs the cpu
to perform various operations as per the
program instruction
the program instructions are stored into
the main memory
ram each program instruction residing in
the memory
is a represented by machine instruction
in binary
these machine instruction in binary can
be directly decoded
and executed by the processor the cpu
initiates the program
execution by fetching decoding and
executing
each instruction one by one the cpu
executes the program
by repetitively performing its basic
operation
called the instruction cycle the
instruction cycle
is a three-step cpu operation which
includes
fetch decode and the execute operation
so now i presume you know how
microprocessor works
let us now move on to the next topic
since we are studying
the microprocessor architecture let us
find out
what is microprocessor architecture is
all about
the term microprocessor architecture is
the design
and the layout of various functional
components
that exist inside the microprocessor
chip
and how these various functional units
interact with each other
when the microprocessor performs various
operations
in order to simplify the study of 8085
architecture
let us group all the microprocessor
components
into five major functional units
each of these functional unit performs a
specific role
these microprocessor functional units
are as follows
the first unit as the memory unit it is
also referred to as
the register unit the second unit is the
arithmetic
and logic unit alu the third unit is the
instruction decoder and the machine
cycle encoder unit
the fourth unit is the timing and
control unit
and finally the fifth unit as the
interrupts
and the serial communication unit let us
now take
a quick look at some important technical
features of the
808.5 microprocessor it is a
8-bit processor and this processor has
total 40 pins it works on
plus 5 volts supply it has a execution
speed of
3 5 and 6 megahertz variants
are available it has 8-bit data bus
in other words it has 8-bit word length
it has 16-bit address bus
and it can address up to 64 kilobyte of
memory
it has a 16-bit program counter register
pc it also has a 16-bit
stack pointer it has 6 8-bit
general purpose registers referred by
its name
that is b c d e and
h l this processor operates at
3.2 megahertz single phase clock
the 8085 processor supports eight
software interrupts
and five hardware interrupts
let us now discuss each of the five 8085
microprocessor functional units
in detail let us start with the first
unit
that is memory unit also called as the
register unit
the internal memory of the processor
built into the processor chip
is called a register in other words
the cpu registers are high speed
temporary memory
present inside the processor chip these
registers are used by the 8085 processor
to store the data addresses and machine
instructions
during the program execution the cpu
makes use of
different types of registers placed
inside the processor chip
the cpu registers can be grouped into
two types the first type is called
general purpose registers and the second
type is called
the special purpose register the general
purpose registers are used
to store the data in the temporary
memory during the program
execution the 8085 processor has
six general purpose registers that can
store
eight bit of data the general purpose
registers
are named as b c d e
h and l these registers can also be
combined
to form a register pair such as bc
di and hl to perform the 16-bit
operations
the 8085 processor also make use of
some special purpose registers during
the execution of the
instruction cycle the special purpose
registers
are used to store a specific type of
data and perform
a special function and therefore they
are called as
special purpose registers some special
purpose registers
are accessible to the programmer whereas
some special purpose registers
are not accessible to the programmer let
us now take
a quick look at some important registers
and
their functions the first register that
comes into action
is the program counter register pc the
program counter register
is a 16-bit special purpose register
used in the 8085 architecture
to store the address of the instruction
that needs to be fetched
from the memory the program counter
register
always stores the memory address of the
next instruction
that needs to be fetched from the main
memory ram
as the processor begins the fetch
operation for the first instruction
the program counter register is
incremented by one
at the same time so that it now points
to the
address of the next instruction that is
to be fetched
from the memory the second register that
comes into action
is the instruction register ir
the instruction register is a 8-bit
special special-purpose register
used by the processor to store the part
of the instruction
that needs to be decoded by the decoder
of the control unit
depending upon the instruction format
the control unit of the cpu
decodes the instruction as specified in
the
op code of the instruction format
the opcode stands for operation code
it is opcode that is decoded by the
decoder
and machine instruction encoder unit the
opcode part of the instruction
is stored into the 8-bit instruction
register
during the execution of the instruction
cycle
the third register that comes into
action is the
accumulator register the accumulator is
considered to be
a part of arithmetic and logic unit alu
the accumulator stores the operand part
of the
instruction format the arithmetic and
logic unit alu
is another important component of the
processor which actually performs
the arithmetic and logical operations
the arithmetic and logic unit of the cpu
performs the desired operation on the
data
placed in the accumulator as per the
operation code
decoded by the decoder of the control
unit
let us now understand what is flag
register
as we have discussed earlier all
arithmetic and logical operations are
performed by the alu
during the alu operations the flag
register plays an important role
the main function of the flag register
is to indicate
the status of the processor after each
alu
operation the flag register is also
alternately referred to as
program status word psw of flag register
is a 8-bit special purpose register used
in 808.5 architecture
to indicate the cpu status after each
arithmetic
and logical operation the 8085 flags
register
can have a total of eight flags each
flag
is represented by a specific bit in the
8-bit
flag register however the 8085
processor use only five flags out of
eight flags
and the remaining three flags are kept
unused
the five flags used in the flag register
include
the carry flag auxiliary carry flag
sign flag parity flag and the zero flag
all right so far we have discussed in
detail
different types of cpu registers and
their respective functions
let us now move on to next important
topic
and that topic is timing and control
unit of the
8085 microprocessor the cpu is driven by
a stream of the clock signals generated
by the
clock circuit built into the processor
chip
these clock signals helps the cpu to
synchronize the operations of
its internal components various
registers
and other external hardware devices
the clock pulses and the control signals
are generated
by the timing and control unit of the
cpu that is built into the processor
chip
the control signals are essential to
manage and control
the operations of the various hardware
devices
connected to the system the control unit
of the
processor also sends the control signals
to all the hardware components and
peripheral devices
necessary to control their operations
the timing and control signals are
essential part of the
instruction cycle which is a basic
operation of the cpu
the cpu to execute the program
instructions
one by one by repetitively performing
the instruction cycle
for each clock pulse the cpu executes
a part of the instruction during the
program execution
okay so now you know the importance of
timing and control unit of the cpu
let us now discuss another important
component of the 8085 architecture
and that topic is interrupts as the name
suggests
the interrupts are used to current
execution sequence of the cpu
the interrupts are the signals sent to
the microprocessor
to pause the current activity and attend
to the request
sent by the external devices in other
words
the interrupts are external events that
occur in real time
to seek the processor response the
interrupts can be generated
either by the program instructions or it
can also be generated by the peripheral
devices
connected to the system the
architecture supports eight software
interrupts
and five hardware interrupts the
interrupt can be classified into the
following groups depending upon their
parameters
the interrupt types are first the
software interrupt
second the hardware interrupt third
vector interrupt
fourth non-vector interrupt fifth
maskable interrupt and finally sixth the
non-maskable interrupt all right
so far we have discussed what are
interrupts
and different types of interrupts used
in the
8085 processor
let us now discuss the final topic of
this video tutorial
which is another important component of
the 8085 architecture
and that topic is 808.5 bus architecture
and the bus interface the computer buses
are
the group of wires running across the
computer system
through which the data address and the
control signals are transferred
the microprocessor needs to communicate
with the
various system hardware components in
order to execute
the program instructions the
microprocessor chip
also has its own internal buses
essential for the
functioning of the processor the 8085
architecture has
8-bit data bus and 16-bit
address bus let us now discuss
different types of buses and its
function
the first component of the bus
architecture is the address bus
the address bus is a 16-bit
unidirectional bus
that is used to transfer the 16-bit
address
between the cpu and the main memory ram
the second component of the bus
architecture is the data bus
the data bus is a 8-bit bi-directional
bus
that is used to transfer the 8-bit data
between the cpu
and the main memory ram the cpu performs
both memory read and write operation
during the program
execution this data transfer takes place
on the data bus the third component of
the
bus architecture is the control bus
the control bus is a bidirectional bus
that is used to transfer
the control signals between the cpu and
the various hardware devices connected
to the computer system
all right so now you have enough
knowledge about
all important cpu components various
functional units
and the technical features for intel
8085
microprocessor architecture
and that brings us to the end of this
tutorial
please read the detailed article on our
website
learncomputerscienceonline.com for more
details
and in this tutorial we have discussed
the intel 8085 architecture in detail
if you have liked this video then please
give us a thumbs up
and do consider to subscribe to this
channel
for more such interesting videos thanks
for watching
and i will see you soon with another
computer science video tutorial
Посмотреть больше похожих видео
Lec-8: Instruction in 8085 | 1B, 2B & 3B Instructions | Opcode & Operand | Microprocessor
Lec-5: Types of Registers in 8085 | Accumulator | General Purpose Register
L-1.4:Types of Buses (Address, Data and Control) in Computer Organization and Architecture
Lec-6: Types of Flag Register in 8085 Microprocessor | Auxiliary carry | Parity | Carry flag
DMA(Direct Memory Access) in 8085 Microprocessor Explained in Hindi l Microprocessor Series
Lec-4: Internal Architecture of 8085 Microprocessor | Working of 8085
5.0 / 5 (0 votes)