19-02-2013, 09:20 AM
EC1362 Microprocessor & Microcontroller
[attachment=51266]
Processor System Architecture
The typical processor system consists of:
CPU (central processing unit)
ALU (arithmetic-logic unit)
Control Logic
Registers, etc…
Memory
Input / Output interfaces
Interconnections between these units:
Address Bus
Data Bus
Control Bus
The 8085 Bus Structure
Address Bus
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) – FF (hex)
The 8085: CPU Internal Structure
The internal architecture of the 8085 CPU is
capable of performing the following operations:
Store 8-bit data (Registers, Accumulator)
Perform arithmetic and logic operations (ALU)
Test for conditions (IF / THEN)
Sequence the execution of instructions
Store temporary data in RAM during execution
Example: Instruction Fetch Operation
All instructions (program steps) are stored in memory.
To run a program, the individual instructions must
be read from the memory in sequence, and executed.
Program counter puts the 16-bit memory address of the
instruction on the address bus
Control unit sends the Memory Read Enable signal to
access the memory
The 8-bit instruction stored in memory is placed on the data
bus and transferred to the instruction decoder
Instruction is decoded and executed
[attachment=51266]
Processor System Architecture
The typical processor system consists of:
CPU (central processing unit)
ALU (arithmetic-logic unit)
Control Logic
Registers, etc…
Memory
Input / Output interfaces
Interconnections between these units:
Address Bus
Data Bus
Control Bus
The 8085 Bus Structure
Address Bus
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) – FF (hex)
The 8085: CPU Internal Structure
The internal architecture of the 8085 CPU is
capable of performing the following operations:
Store 8-bit data (Registers, Accumulator)
Perform arithmetic and logic operations (ALU)
Test for conditions (IF / THEN)
Sequence the execution of instructions
Store temporary data in RAM during execution
Example: Instruction Fetch Operation
All instructions (program steps) are stored in memory.
To run a program, the individual instructions must
be read from the memory in sequence, and executed.
Program counter puts the 16-bit memory address of the
instruction on the address bus
Control unit sends the Memory Read Enable signal to
access the memory
The 8-bit instruction stored in memory is placed on the data
bus and transferred to the instruction decoder
Instruction is decoded and executed