8085 microprocessor
EE 201 : Digital Circuits and
Microprocessors
Dr. Amit Sethi
Room 303, EEE Dept.
2529, amitsethi
Objectives for this session
Introduce the 8085 Microprocessor
Introduction to 8085 programming model
Introduction to 8085 instruction set
All computers are based on the Turing
Machine concept
• In 1937, Alan Turing described this abstract idea of a computer
• Turing Machines consist of:
– A tape of infinite length with symbols printed in cells
– A read-write head that can move along the tape to read and write symbols
– A state from a finite set stored inside the machine
– A finite set of instructions that translate the current state and the read symbol into an action which can be:
• Change to another state
• Move to another place on the tape
• Write a symbol on the tape
Computer: Basic definitions
• Computer is a machine that sequentially and automatically carries out a sequence of arithmetic or logical operations given as instructions in form of a program, which can be changed readily, allowing the computer to solve more than one kind of problem • Data and programs can be read from memories, storage or input devices • Data can be written into memory, storage and output devices
Computer components: Memory
• Write: An arbitrary word can be written into the memory • Store: Memory can store data (multiple words)
• Read: An arbitrary word can be read from the memory for usage
• Examples so far
– Data latches are 1-bit memories
– Registers are 1-word (e.g. 1-byte) memories
• But, we want to study bigger memories
Each bit of a memory is a latch
I1
2n lines out
DECODER
n-bit address in bit Lx
EN
D
… From x-1
… From x-1
I0
EN
Q
D
Q
Lx+1
EN
D
EN
Q
D
Q
• To write a bit, we need to enable the latch
(Lx=1)
• This can be done for all the bits in the word
• We can add multiple lines with their respective selects
• For each line, only the enabled output
Microprocessors
Dr. Amit Sethi
Room 303, EEE Dept.
2529, amitsethi
Objectives for this session
Introduce the 8085 Microprocessor
Introduction to 8085 programming model
Introduction to 8085 instruction set
All computers are based on the Turing
Machine concept
• In 1937, Alan Turing described this abstract idea of a computer
• Turing Machines consist of:
– A tape of infinite length with symbols printed in cells
– A read-write head that can move along the tape to read and write symbols
– A state from a finite set stored inside the machine
– A finite set of instructions that translate the current state and the read symbol into an action which can be:
• Change to another state
• Move to another place on the tape
• Write a symbol on the tape
Computer: Basic definitions
• Computer is a machine that sequentially and automatically carries out a sequence of arithmetic or logical operations given as instructions in form of a program, which can be changed readily, allowing the computer to solve more than one kind of problem • Data and programs can be read from memories, storage or input devices • Data can be written into memory, storage and output devices
Computer components: Memory
• Write: An arbitrary word can be written into the memory • Store: Memory can store data (multiple words)
• Read: An arbitrary word can be read from the memory for usage
• Examples so far
– Data latches are 1-bit memories
– Registers are 1-word (e.g. 1-byte) memories
• But, we want to study bigger memories
Each bit of a memory is a latch
I1
2n lines out
DECODER
n-bit address in bit Lx
EN
D
… From x-1
… From x-1
I0
EN
Q
D
Q
Lx+1
EN
D
EN
Q
D
Q
• To write a bit, we need to enable the latch
(Lx=1)
• This can be done for all the bits in the word
• We can add multiple lines with their respective selects
• For each line, only the enabled output