02-03-2013, 11:55 AM
ARCHITECHTURE OF 8085
[attachment=52394]
Arithmetic and Logic Unit (ALU):
It is used to perform the arithmetic operations like addition, subtraction, multiplication, division, increment and decrement and logical operations like AND, OR and EX-OR.
ALU includes Accumulator, Temporary Register, Arithmetic and Logic Circuits and five Flags.
It receives the data from accumulator and registers.
According to the result it set or reset the flags.
Accumulator (A):
The accumulator is an 8-bit register that is part of the ALU.
This register is used to store 8-bit data and to perform arithmetic and logical operations.
The result of an operation is stored in the accumulator.
Temporary Register:
It is used to hold the data during the arithmetic and logical operations.
Flags:
The ALU includes five flip-flops that are set or reset according to the result of an operation.
The microprocessor uses the flags for testing the data conditions.
They are Zero (Z), Carry (CY), Sign (S), Parity (P), and Auxiliary Carry (AC) flags. The most commonly used flags are Sign, Zero, and Carry.
Registers of 8085:
The 8085 have six general-purpose registers to store 8-bit data during program execution.
These registers are identified as B, C, D, E, H, and L.
They can be combined as register pairs-BC, DE, and HL-to perform some 16-bit operations.
Register array consists of two 16-bit registers PC and SP.
Two additional registers called Temporary Registers W and Z are included in register array.
These Temporary Registers are used to hold 8-bit data during the execution of some instructions.
These Temporary Registers are not available to the programmer because it is used internally.
Timing and Control unit:
It has three control signals ALE, RD (Active low) and WR (Active low) and three status signals IO/M (Active low), S0 and S1.
ALE is used for provide control signal to synchronize the components of microprocessor and timing for instruction to perform the operation.
RD (Active low) and WR (Active low) are used to indicate whether the operation is reading the data from memory or writing the data into memory respectively.
IO/M (Active low) is used to indicate whether the operation is belongs to the memory or peripherals.
[attachment=52394]
Arithmetic and Logic Unit (ALU):
It is used to perform the arithmetic operations like addition, subtraction, multiplication, division, increment and decrement and logical operations like AND, OR and EX-OR.
ALU includes Accumulator, Temporary Register, Arithmetic and Logic Circuits and five Flags.
It receives the data from accumulator and registers.
According to the result it set or reset the flags.
Accumulator (A):
The accumulator is an 8-bit register that is part of the ALU.
This register is used to store 8-bit data and to perform arithmetic and logical operations.
The result of an operation is stored in the accumulator.
Temporary Register:
It is used to hold the data during the arithmetic and logical operations.
Flags:
The ALU includes five flip-flops that are set or reset according to the result of an operation.
The microprocessor uses the flags for testing the data conditions.
They are Zero (Z), Carry (CY), Sign (S), Parity (P), and Auxiliary Carry (AC) flags. The most commonly used flags are Sign, Zero, and Carry.
Registers of 8085:
The 8085 have six general-purpose registers to store 8-bit data during program execution.
These registers are identified as B, C, D, E, H, and L.
They can be combined as register pairs-BC, DE, and HL-to perform some 16-bit operations.
Register array consists of two 16-bit registers PC and SP.
Two additional registers called Temporary Registers W and Z are included in register array.
These Temporary Registers are used to hold 8-bit data during the execution of some instructions.
These Temporary Registers are not available to the programmer because it is used internally.
Timing and Control unit:
It has three control signals ALE, RD (Active low) and WR (Active low) and three status signals IO/M (Active low), S0 and S1.
ALE is used for provide control signal to synchronize the components of microprocessor and timing for instruction to perform the operation.
RD (Active low) and WR (Active low) are used to indicate whether the operation is reading the data from memory or writing the data into memory respectively.
IO/M (Active low) is used to indicate whether the operation is belongs to the memory or peripherals.