01 INTRODUCTION TO MICROPROCESSORS and embedded systems .pdf

INTRODUCTION TO
MICROPROCESSORS
TI Chinonyiwa 2025
isaachinoes@gmail.com
Microprocessor Electronics

INTRODUCTION
• A microprocessor is a controlling unit of a micro-computer fabricated
on a small chip capable of performing ALU (Arithmetic Logic Unit)
operations and communicating with other devices connected to it.
• It consists of register set, control array, and control unit.
• The ALU performs arithmetical and logical operations on the data
received from the memory or an input device.
• Register array consists of registers identified by letters like B, C, D, E,
H, L, and accumulator. The control units control the flow of data and
instructions within the computer.
©2025 TI CHINONYIWA

INTRODUCTION
• It is programmable in a way to read binary instructions from memory
and then execute the task to deliver the needed output.
• It is useful for storing data, device interaction, and sending/receiving
data simultaneously.
• A Microprocessor has many components like transistors, registers, and
diodes which come together to perform.
• The ability of the chip has become more complex with technology
evolution.
• The functionality has become better and the speed has become faster.

INTRODUCTION
• Most devices need to have a microprocessor to function.
• It is the element that brings intelligence to a device.
• Be it a computer or mobile phone, all devices need an interface to
handle data that only a microprocessor provides.

HOW A MICROPROCESSOR WORKS
• The microprocessor follows a sequence: Fetch, decode and then
execute.
• The instructions are stored in the memory in sequential order.
• The microprocessor fetches those instructions from memory, then
decodes them and executes those instructions till STOP instruction is
reached.
• It then sends the result in binary to the output port.
• The task of the register is to store data temporarily, and ALU performs
the computing functions.

FEATURES OF MICROPROCESSOR
• It is low in cost as it uses integrated circuit technology reducing the overall cost of
a computer system.
• It generates less heat as semiconductors emit less heat in comparison to vacuum
tube devices.
• The microprocessor has a very high speed due to advanced technology, executing
millions of instructions every second.
• It consumes low power because of metal oxide semiconductor technology.
• Its small size and less power consumption make it portable as well.
• It is small in size due to less footprint but has a large-scale integration technology.
• It has a versatile nature as it is usable for several applications.
• The microprocessor has a very low failure rate becoming reliable for the computer
system.

TYPES OF MICROPROCESSORS
• RISC Processor: – Reduced Instruction Set Computer. It is designed to
reduce the execution time by simplifying the instruction set of the computer.
• CISC Processor: – Complex Instruction Set Computer. It is designed to
minimize the number of instructions per program, ignoring the number of
cycles per instruction.
• Special Processor: – These processors are designed for special purposes.
• Some of the special processors are as follows
• Coprocessor
• Input/output Processor
• Transputer
• Digital Signal Processor

VON NEUMANN ARCHITECTURE
• Was first published by John von Neumann in 1945.
• His computer architecture design consists of a Control Unit,
Arithmetic and Logic Unit (ALU), Memory Unit, Registers and
Inputs/Outputs.
• Von Neumann architecture is based on the stored-program computer
concept, where instruction data and program data are stored in the
same memory.

KEY ELEMENTS OF VON NEUMANN
ARCHITECTURE
• data and instructions are both stored as binary.
• data and instructions are both stored in main memory.
• instructions are fetched from memory one at a time and in order -
serially.
• the processor decodes and executes an instruction, before cycling
around to fetch the next instruction.
• the cycle continues until no more instructions are available.

REGISTERS
• A processor based on Von Neumann architecture has five special registers
which it uses for processing:
• Program counter (PC) - holds the memory address of the next instruction to be
fetched from main memory.
• Memory address register (MAR) - holds the address of the current instruction that is
to be fetched from memory, or the address in memory to which data is to be
transferred.
• Memory buffer register (MBR) - holds the contents found at the address held in the
MAR, or data which is to be transferred to main memory. It is also referred to as the
memory data register (MDR).
• Current instruction register (CIR) - holds the instruction that is currently being
decoded and executed.
• Accumulator (ACC) - holds the data being processed and the results of processing.

HARVARD ARCHITECTURE
• Is the computer architecture that contains separate storage and separate
buses (signal path) for instruction and data.
• It refers to a memory structure in which the processor is connected to
two independent memory banks via two independent sets of buses.
• It was developed to overcome the bottleneck of Von Neumann
architecture.
• The main advantage of having separate buses for instruction and data
is that the CPU can access instructions and read/write data at the same
time, i.e. two memory accesses can be made during any one
instruction cycle.

STRUCTURE OF HARVARD ARCHITECTURE

BUSES
• Are used as signal pathways
• There are separate buses for both instruction and data in Harvard
architecture.
• Data Bus: carries data among the main memory, processor and I/O
devices.
• Data Address Bus: carries the address of data from the processor.
• Instruction Bus: carries instruction among the main memory system,
processor, and I/O devices.
• Instruction Address Bus: carries the address of instructions from the
processor.

OPERATIONAL REGISTERS
• There are different types of registers involved which are used for
storing addresses of different types of instructions.
• e.g. Memory Address Register and Memory Data Registers.

PROGRAM COUNTER
• Stores the location of the next instruction to be executed.
• It then passes this next address to the memory address register.

ARITHMETIC AND LOGIC UNIT
• It operates on all the calculations needed.
• It performs addition, subtraction, comparison, logical operations, bit
shifting operations and various arithmetic operations.

CONTROL UNIT
• It operates all processor control signals.
• It controls input and output devices and also controls the movement of
instructions and data within the system

INPUT/OUTPUT SYSTEM
• Input devices are used to read data into main memory with the help of
CPU input instruction.
• The information from a computer as output is given through output
devices.

RISC
• A Reduced Instruction Set Computer is a type of microprocessor
architecture that utilizes a small, highly optimized set of instructions
rather than the highly specialized set of instructions found in other
architectures.
• With RISC, a CPU implements the processor design principle of
simplified instructions that can do less but can execute more rapidly.
• A key RISC feature is that it allows developers to increase the register
set and increase internal parallelism by increasing the number of
parallel threads executed by the CPU and increasing the speed of the
CPU’s executing instructions.

DESIGN FEATURES
• one cycle execution time: RISC processors have a CPI (clock per
instruction) of one cycle. This is due to the optimization of each
instruction on the CPU and a technique called ;
• pipelining: a technique that allows for simultaneous execution of parts,
or stages, of instructions to more efficiently process instructions;
• large number of registers: the RISC design philosophy generally
incorporates a larger number of registers to prevent in large amounts
of interactions with memory

CISC
• A processor in which individual instructions may perform many
operations and take many cycles to execute.
• The main idea is that a single instruction will do all loading,
evaluating, and storing operations, e.g. a multiplication command will
do stuff like loading data, evaluating, and storing it, hence it’s
complex.

CISC
• The primary goal of CISC architecture is to complete a task in as few lines
of assembly as possible.
• This is achieved by building processor hardware that is capable of
understanding and executing a series of operations.
• For this particular task, a CISC processor would come prepared with a
specific instruction (we'll call it "MULT").
• When executed, this instruction loads the two values into separate registers,
multiplies the operands in the execution unit, and then stores the product in
the appropriate register.
• Thus, the entire task of multiplying two numbers can be completed with one
instruction:
• MULT 2:3, 5:2

TODAY’S QUOTE
“Live in the sunshine, swim the sea, drink the wild
air.”
Ralph Waldo Emerson

01 INTRODUCTION TO MICROPROCESSORS and embedded systems .pdf

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