PPT Of Unit 1 of Microprocessor & Microcontroller.ppt

MICROPROCESSOR &
MICROCONTROLLER
UNIT 1
INTRODUCTION TO MICROPROCESSOR
Faculty: GHANSHYAM MISHRA
Department Of ECE

Text Books:
1. Microprocessor Architecture, Programming, and
Applications with the 8085 – Ramesh Gaonkar

A Programmable Machine
• Multipurpose,
programmable, clock-
driven, register-based
electronic device.
• Memory-storage device.
• Input- to accept data
• Output- to provide result.

Traditional Block Diagram of a
Computer
•Four components-
1.Memory
2.Input device
3.Output device
4.CPU

Computer with Microprocessor as
CPU
•CPU on a single chip-
microprocessor

Block Diagram of a Microcontroller
Microcontroller- an
entire computer on a
single chip.

Advances in Semiconductor
Technology
• SSI- Small Scale Integration
• MSI-Medium Scale Integration
• LSI- Large Scale Integration
• VLSI- Very Large Scale Integration

Evolution of Microprocessors
First microprocessor released by IntelCorporation in
1971 was INTEL 4004.
First Generation Microprocessors:
• Introduced between 1971 and 1973.
• Designed using PMOS technology.
• Having low cost, slow speed and low output currents.
• Not compatible with TTL.
• 4-bit processors- INTEL 4004, INTEL 4040,
NATIONAL IMP-4.
• 8-bit processors- INTEL 8008, NATIONALIMP-8.
• 16 bit processors- NATIONAL PACE.

Second Generation Microprocessors:
• Introduced in 1973.
• Designed using NMOS technology.
• Offers faster speed and higher density.
• Compatible with TTL.
• 8-bit processors- INTEL 8080, INTEL 8085,
NATIONAL cMP-8.
• 12 bit Processors- TOSHIBA TLCS- 12.
• 16 bit processors- TI TMS 9900.

Third Generation Microprocessors:
• Introduced after 1978.
• Designed using HMOS technology.
• Offers high speed and very strong processing
capability.
• Easier to program.
• 16 bit processors- INTEL 8086, INTEL 8088,
INTEL 80186, INTEL 80286, TI TMS 99000.

Fourth Generation Microprocessors:
• Introduced in 1980.
• Designed using low power version of HMOS
technology called HCMOS.
• 32 bit processors- INTEL 80386, INTEL 80486,
MOTOROLA M68020.
Fifth Generation Microprocessors:
• INTEL pentium released in 1993.
• 32-bit processor.

Microprocessor-based System
with Bus Architecture
• Microprocessor-
ALU
Register Array
Control Unit
• Memory-
ROM
RAM
• I/O
• System Bus

Microprocessor buses and Its
Operations
Three sets of
communication lines are
called buses-
1.Address bus
2.Data bus
3.Control bus
The 8085 Bus Architecture

Address Bus-
•used to identify a peripheral or memory location.
•Consists of 16 address lines: A0 – A15.
•Operates in unidirectional mode: The address bits are always sent
from the MPU to peripheral devices, not reverse.
•16 address lines are capable of addressing a total of 216
= 65,536
(64k) memory locations.
•Address locations: 0000 (hex) – FFFF (hex).
Data Bus-
•Consists of 8 data lines: D0 – D7.

• Operates in bidirectional mode: The data bits are sent from the
MPU to peripheral devices, as well as from the peripheral devices
to the MPU.
• Data range: 00 (hex) – FF (hex)
Control Bus-
• Consists of various lines carrying the control signals such as read /
write enable, flag bits.

Microprocessor Architecture and
Its Operations
Microprocesor functions are classified as-
1. Microprocessor-initiated operations
•Memory read.
•Memory write.
•I/O read.
•I/O write.
2. Internal operatins
•Store 8-bit data.
•Perform arithmetic and logical operations.
•Test for conditions.
•Sequence the execution of instructions.
•Store data temporarily.
3. Peripheral ( or externally initiated ) operations
•Reset
•Interrupt
•Ready
•Hold

Register Array:
•Six general purpose registers- B,C,D,E,H,L.
Accumulator:
•Used to store 8 bit data and to perform arithmetic and
logical operations.
•Used to store the result.
Program Counter and Stack Pointer:
•Used to hold memory address.
W and Z Registers:
•Not available to the programmer.
•Used to hold 8-bit data during execution of some
instructions.

General features of 8085
Microprocessor for 2 marks
• 8-bit microprocessor introduced by INTEL in 1977.
• Has 16 address lines.
• 40 pin IC present in DIP.
• Capable of addressing 64KB of memory.
• Has 8 data lines.
• Low-order address bus is multiplexed with the data bus.
• Requires a +5V single power supply.
• Can operate with 3MHz clock.

General features of 8085
Microprocessor for 10 marks
• The Intel 8085 is an 8-bit microprocessor that was
widely used in the late 1970s and early 1980s. It
has several general features:
• 8-bit Data Bus: The 8085 has an 8-bit data bus,
which means it can process data in 8-bit chunks at
a time.
• 16-bit Address Bus: It has a 16-bit address bus,
allowing it to address up to 64 KB (64,000 memory
locations) of memory.
• Clock Speed: The 8085 typically operates at a clock
speed of 3 MHz, although some versions and
applications could run at different frequencies.

• Registers: It has six general-purpose registers (B, C, D, E, H,
and L), which can be combined as register pairs (BC, DE, and
HL). It also has a 16-bit stack pointer (SP) and a 16-bit
program counter (PC).
• Instruction Set: The 8085 has a relatively simple and
straightforward instruction set with 74 instructions.
Instructions are typically one to three bytes long.
• Flags: It has five flags in the flag register: Sign (S), Zero (Z),
Auxiliary Carry (AC), Parity (P), and Carry (CY). These flags are
used to indicate various conditions after arithmetic and logic
operations.
• Interrupts: The 8085 supports five interrupt lines: TRAP,
RST 7.5, RST 6.5, RST 5.5, and INTR. It can handle both
hardware and software interrupts

• serial I/O Control: It has serial input and output lines
that can be controlled for serial data communication.
• Instruction Pipelining: The 8085 uses a simple
pipeline architecture, which means it can fetch the
next instruction while executing the current one.
• Memory Addressing Modes: It supports various
addressing modes, including direct addressing,
register addressing, immediate addressing, and
indirect addressing.
• On-Chip Clock Generator: The 8085 includes an on-
chip clock generator circuit, simplifying the external
circuitry required for clock generation.

Power Supply: It typically operates on a single +5V power
supply.
Minimum and Maximum Mode: The 8085 can operate in
minimum mode, where it uses externally connected
components for interfacing, or maximum mode, where it
uses additional pins to communicate with external
components like co-processors.
Instruction Execution Time: The execution time for most
instructions ranges from 4 to 10 machine cycles,
depending on the complexity of the instruction.
Binary Coded Decimal (BCD) Arithmetic: The 8085 has
instructions to perform BCD arithmetic operations directly

The signals of 8085 can be classified into 6 groups-
1.Address bus
2.Data bus
3.Control and status signals
4.Power supply and frequency signals
5.Externally initiated signals
6.Serial I/O ports

• A15-A8 (Address Bus): These are the high-order address
lines used to specify the memory or I/O device address. The
8085 can address up to 64K (64,000) different memory
locations.
• AD7-AD0 (Data Bus): These are the bi-directional data lines
used to transfer data between the microprocessor and
memory or I/O devices. The 8085 is an 8-bit
microprocessor, so it can transfer 8 bits of data at a time.
• ALE (Address Latch Enable): ALE is used to latch the
address from the multiplexed address/data bus into the
external latch or memory ICs. It is activated during the
first clock cycle of each machine cycle.

• S0 and S1 (Status Lines): These status lines indicate the
status of the microprocessor during different machine
cycles. They are used for interfacing with other devices and
for control purposes.
• SID (Serial Input Data): This pin is used for serial data
input when interfacing with serial devices.
• SOD (Serial Output Data): This pin is used for serial data
output when interfacing with serial devices.
• RESET IN (Reset Input): When a high signal is applied to
this pin, it resets the microprocessor, causing it to restart
execution from the address 0000H.

• X1 and X2 (Crystal Oscillator Input and Output): These pins
are used to connect an external crystal oscillator or clock
source to provide the microprocessor with the required clock
signal for operation.
• INTR (Interrupt Request): This is the interrupt request
input. When a high-level signal is applied to this pin, it
requests the microprocessor to service an interrupt.
• INTA (Interrupt Acknowledge): This output is used to
acknowledge an interrupt request. It indicates that the
microprocessor is ready to service an interrupt.
• HOLD and HLDA (Hold Request and Hold Acknowledge):
These pins are used for holding the microprocessor's
operation temporarily, allowing external devices to gain
control of the system bus.

• READY: This input indicates to the microprocessor that the
external devices are ready to provide or accept data. It is
used to insert wait states if needed.
• RST 7.5, RST 6.5, and RST 5.5: These are hardware
interrupt request inputs for specific vectored interrupts.
• TRAP: This is a non-maskable interrupt (NMI) input. When a
high-level signal is applied to this pin, it generates an NMI.
• RESET OUT: This is the reset output pin. It provides a
reset signal to other devices in the system when the
microprocessor is reset.
• +5V and GND: These pins are used to provide the power
supply to the microprocessor. +5V is the positive voltage
supply, and GND is the ground reference.

The remaining pins are used for various control
signals, clock-related signals, and interfacing with
memory and peripheral devices.
Understanding the pin diagram of the 8085
microprocessor is essential for interfacing it with
memory, input/output devices, and other components
in a computer or embedded system design.

Memory
• Stores binary instructions and data for the microprocessor.
• Can be classified in two groups- Prime (main) memory and storage memory.
• Prime memory- Read/Write memory (R/WM) and Read-Only memory (ROM).
• R/WM-
Made of registers and each register has a group of flip-flops.
Flip-flop- memory cell.
Memory word- number of bits stored in a register.
Used to hold programs and store data.
• ROM-
Stores information permanently in the form of diodes.
Group of diodes- register.
• Memory Address- binary numbers by which all registers are identified.
• To communicate with memory, the MPU should be able to-
select the chip.
identify the register, and
read from or write into the register.

Memory Model
R/W Memory Model and ROM Model

R/WM-
•Popularly known as RAM.
•Information stored can be altered.
•Volatile.
•Two types- Static and Dynamic.
Static Memory (SRAM)-
•Made up of flip flops, stores the bit as a voltage.
•Low density but high speed.
•More expensive and consumes more power.
Dynamic Memory (DRAM)-
•Made up of MOS transistor gates, stores the bit as a charge.
•High density and low power consumption.
•Cheaper.

• Refreshing is required.
ROM-
• Nonvolatile memory.
• Information can be read only.
• Permanent group includes- masked ROM and PROM.
• Semipermanent group includes- EPROM and EE-PROM.
Masked ROM-
• Bit pattern is permanently recorded.
PROM-
• Programmable Read-Only Memory.
• Memory can be programmed by the user.
• Information stored is permanent.

EPROM-
•Erasable Programmable Read-Only Memory.
•Erasing is done through ultraviolet light.
EEPROM-
•Electrically Erasable PROM.
•Erasing is done using electrical signals.
Flash Memory-
•Can be erased either in it entirely or at the sector or block level.

Input and Output Devices
There are two different methods by which I/O devices can be
identified-
1.I/Os with 8 bit addresses ( Peripheral –mapped I/O)-
• MPU uses eight address lines to identify an I/O device.
• Also known as I/O mapped I/O.
• The I/O map is independent of the memory map; 256 input
device and 256. output device can be connected.
• Less hardware is required to decode 8-bit address.
• I/O devices are differentiated by the control signals.
• The I/O devices are treated as I/O devices and the memory is
treated as memory.

2. I/Os with 16 bit addresses ( Memory–mapped I/O)-
• MPU uses 16 address line.
• The processor treats the I/O devices like any other memory
location
• MPU uses the same control signal and instructions as those of
memory.
• I/Os and memory share the same memory map (64K).

Demultiplexing the Bus AD7-AD0
Schematic of Latching Low-Order Address Bus

• ALE is high every time the 8085 begins an
operation.
• When the ALE is high, the latch is transparent.
• When the ALE is low, data byte is latched until
the next ALE, and hence output of the latch
represents the low-order address.

Generating Control Signals
Schematic to generate Read/Write control
signals for memory and I/O
8085 demultiplexed address and data bus
with control signals

Flag Register
There are 5 flags:
1.S-Sign Flag
2.Z-Zero Flag
3.AC-Auxiliary Carry Flag
4.P-Parity Flag
5.CY-Carry Flag
Flag Register of 8085

Timing Diagrams
Timing Diagram: Pictorial representation of execution of
an instruction using various control, timing and status
signals.
Instruction Cycle: Time required to complete the
execution of an instruction. It consists one to six
operations.
Machine Cycle: Time required to complete one operation.
It consists three to six T-states.
T-state: One sub-division of an operation performed in
one clock period.

Opcode Fetch Machine Cycle
• It is the first step of executing any instruction.
• Microprocessor brings in the instruction’s opcode from
memory.
• The control and status signals are set as follows:
• IO/M=0, S0 and S1 both are 1.
• This machine cycle has 4 or 6 T-states. First three T-
states are used to fetch the opcode and T4 is used to
decode and execute.

8085 Timing for Execution of the
Instruction MVI A,32H

PPT Of Unit 1 of Microprocessor & Microcontroller.ppt

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