1. created by :Gaurav Shrivastava contact:-gaurav9915969367@ymail.com
INTEL 8085

2. Organization of A Microprocessor-based System (Computer)
created by :Gaurav Shrivastava
Organization of A Microprocessor-based System (Computer)
CPU – Central Processing Unit
Memory
ROM – Read Only Memory
RAM – Random Access Memory
I/O
Keyboard
Display Device
Clock – Square Wave Oscillator (Timing)
System Bus

3. created by :Gaurav Shrivastava contact:-gaurav9915969367@ymail.com
Microprocessor (CPU)
Programmable integrated device (silicon chip) that has computing & decision making capabilities
Communicates & operates in binary numbers 0 & 1, called bits
Has a fixed set of instructions in the form of binary patterns – machine language
Difficult for humans to remember machine language – each instruction is represented using abbreviated names (mnemonics)

4. Memory Symbolic representation Word length 1 word instruction
created by :Gaurav Shrivastava
Memory
Symbolic representation
Word length
1 word instruction
2 word instruction
Word: no. of bits micro-P recognizes and processes at a time ( bit ).
Instruction: combination of bit patterns with specific meaning known to micro-P.
Program: Set of all instructions.
address

5. I/O Microprocessor’s connection to the outside world
created by :Gaurav Shrivastava
I/O
Microprocessor’s connection to the outside world
Input: Keyboard, mouse
Output: Monitor, printer

6. System Bus – wires connecting memory & I/O to microprocessor
created by :Gaurav Shrivastava
System Bus – wires connecting memory & I/O to microprocessor
Address Bus
Unidirectional
Identifying peripheral or memory location
Data Bus
Bidirectional
Transferring data
Control Bus
Synchronization signals
Timing signals
Control signal

7. Actions performed by microprocessor:
created by :Gaurav Shrivastava
Actions performed by microprocessor:
CPU – Memory
CPU – I/O
Data Processing
Arithmetic operations
Logical operations
Control
Jump
Interrupts

8. Basic Concepts of Microprocessors
created by :Gaurav Shrivastava
Basic Concepts of Microprocessors
Differences between:
Microcomputer – a computer with a microprocessor as its CPU. Includes memory, I/O etc.
Microprocessor – silicon chip which includes ALU, register circuits & control circuits
Microcontroller – silicon chip which includes microprocessor, memory & I/O in a single package.

9. Differences between: High level language Assembly language
created by :Gaurav Shrivastava
Differences between:
High level language
Assembly language
Machine language

10. Architecture of Intel 8085 Microprocessor
created by :Gaurav Shrivastava
Architecture of Intel 8085 Microprocessor

11. Intel 8085 Microprocessor Microprocessor consists of:
created by :Gaurav Shrivastava
Intel 8085 Microprocessor
Microprocessor consists of:
Control unit: control microprocessor operations.
ALU: performs data processing function.
Registers: provide storage internal to CPU.
Interrupts
Internal data bus

12. Registers General Purpose Registers Special Purpose Registers
created by :Gaurav Shrivastava
Registers
General Purpose Registers
B, C, D, E, H & L (8 bit registers)
Can be used singly
Or can be used as 16 bit register pairs
BC, DE, HL
H & L can be used as a data pointer (holds memory address)
Special Purpose Registers
Accumulator (8 bit register)
Store 8 bit data
Store the result of an operation
Store 8 bit data during I/O transfer

13. created by :Gaurav Shrivastava contact:-gaurav9915969367@ymail.com
Flag Register
8 bit register – shows the status of the microprocessor before/after an operation
S (sign flag), Z (zero flag), AC (auxillary carry flag), P (parity flag) & CY (carry flag)
Sign Flag
Used for indicating the sign of the data in the accumulator
The sign flag is set if negative (1 – negative)
The sign flag is reset if positive (0 – positive) D7 D6 D5 D4 D3 D2 D1 D0 S Z X AC P CY

14. Zero Flag Carry Flag Is set if result obtained after an operation is 0
created by :Gaurav Shrivastava
Zero Flag
Is set if result obtained after an operation is 0
Is set following an increment or decrement operation of that register
Carry Flag
Is set if there is a carry or borrow from arithmetic operation
Carry
Borrow

15. Auxillary Carry Flag Parity Flag
created by :Gaurav Shrivastava
Auxillary Carry Flag
Is set if there is a carry out of bit 3
Parity Flag
Is set if parity is even
Is cleared if parity is odd

16. 16 – Bit Registers Program Counter Stack Pointer
created by :Gaurav Shrivastava
16 – Bit Registers
Program Counter
A pointer to the next instruction to be executed
Contains the 16-bit memory address of the next instruction
Updated after processor has fetched the instruction
Stack Pointer
Stack – an area in memory in which temporary info is stored
Stack – FILO (First In Last Out) basis
Holds the address of the top of the stack

17. Non Programmable Registers
created by :Gaurav Shrivastava
Non Programmable Registers
Instruction Register & Decoder
Instruction is stored in IR after fetched by processor
Decoder decodes instruction in IR
Internal Clock generator
3.125 MHz internally
6.25 MHz externally

18. Basic Working of a Microprocessor
created by :Gaurav Shrivastava
Basic Working of a Microprocessor
Instructions are stored sequentially in memory
Microprocessor
Fetches instruction from memory
Decodes instruction
Executes instruction

19. Interrupts of 8085 Microprocessor
created by :Gaurav Shrivastava
Interrupts of 8085 Microprocessor
Maskable Interrupts
Microprocessor can ignore or delay interrupt request
INTR – General purpose interrupt
RST 5.5, RST 6.5, RST 7.5 – Restart interrupts, higher priorities
Nonmaskable Interrupts
Enabled by default
Cannot be disabled
Microprocessor must respond to it immediately
TRAP – highest priority

20. Grouping of Signals of 8085 Microprocessor
created by :Gaurav Shrivastava
Grouping of Signals of 8085 Microprocessor
Power supply and frequency signals
Address bus signals
Data bus signals
Control and status signals
Externally initiated signals & external signal acknowledgement
Serial I/O port signals

21. Address bus signals, Data bus signals
created by :Gaurav Shrivastava
Address bus signals, Data bus signals
AD0-AD7, A8-A15
16 address lines – 2 sets
Most significant bits (A8-A15) – single directional
Least significant bits (AD0-AD7) – bidirectional
Multiplexed with the bits of bi-directional data bus
It is used as both address and data bus

22. Control and status signals
created by :Gaurav Shrivastava
Control and status signals
Status lines:
IO/M
Differentiate I/O and memory applications
High – I/O
Low – Memory
S1, S0 – status signals, to indicate the type of machine cycle in progress
Control lines:
RD, WR & INTA
RD – data on the data bus to be read into processor
WR – data on the data bus to be written to processor
INTA – acknowledge an INTR interrupt _ _ _ _ _

23. Externally initiated signals & signal acknowledgement
created by :Gaurav Shrivastava
Externally initiated signals & signal acknowledgement
Initiated signals
Reset In – reset CPU
Hold – suspend CPU operation
Ready – CPU go into wait state, to sync with slower devices
Signal acknowledgement
Reset out – high once CPU is rest
HLDA – acknowledges hold signal

24. created by :Gaurav Shrivastava contact:-gaurav9915969367@ymail.com

25. created by :Gaurav Shrivastava contact:-gaurav9915969367@ymail.com