25-07-2012, 03:20 PM
MICROPROCESSORS and MICROCONTROLLER
[attachment=28922]
8085 INTRODUCTION
The features of INTEL 8085 are :
•It is an 8 bit processor.
•It is a single chip N-MOS device with 40 pins.
•It has multiplexed address and data bus.(AD0 -AD7 ).
•It works on 5 Volt dc power supply.
•The maximum clock frequency is 3 MHz while minimum frequency is 500kHz.
•It provides 74 instructions with 5 different addressing modes.
Arithmetic and Logical group
Accumulator:
It is 8 bit general purpose register.
It is connected to ALU.
Most of the operations are done in Acc.
Temporary register:
It is not available for user
All the arithmetic and logical operations are done in the temporary register but user can’t access it.
Flag:
It is a group of 5 flip flops used to know status of various operations done.
Flag Register along with Accumulator is called PSW or Program Status Word.
Register Group
Stack Pointer: Temporary storage memory 16 bit register. Since there are only 6 general purpose registers, there is a need to reuse them.
•Whenever stack is to be used previous values are PUSHED on stack and then after the program is over these values are POPED back.
Program Counter: It is 16 bit register used to point the location from which the next instruction is to be fetched.
When a single byte instruction is executed PC is automatically incremented by 1.
•Upon reset PC contents are set to 0000H and next instruction is fetched onwards.
STACK AND MACHINE CONTROL
POP Rp.(Pop register pair contents from stack).
Example
OP D(POP the content of DE pair from Stack).
•
Suppose at DE pair the data is H= 20H,L= 30H SP was initialized at FFH
[attachment=28922]
8085 INTRODUCTION
The features of INTEL 8085 are :
•It is an 8 bit processor.
•It is a single chip N-MOS device with 40 pins.
•It has multiplexed address and data bus.(AD0 -AD7 ).
•It works on 5 Volt dc power supply.
•The maximum clock frequency is 3 MHz while minimum frequency is 500kHz.
•It provides 74 instructions with 5 different addressing modes.
Arithmetic and Logical group
Accumulator:
It is 8 bit general purpose register.
It is connected to ALU.
Most of the operations are done in Acc.
Temporary register:
It is not available for user
All the arithmetic and logical operations are done in the temporary register but user can’t access it.
Flag:
It is a group of 5 flip flops used to know status of various operations done.
Flag Register along with Accumulator is called PSW or Program Status Word.
Register Group
Stack Pointer: Temporary storage memory 16 bit register. Since there are only 6 general purpose registers, there is a need to reuse them.
•Whenever stack is to be used previous values are PUSHED on stack and then after the program is over these values are POPED back.
Program Counter: It is 16 bit register used to point the location from which the next instruction is to be fetched.
When a single byte instruction is executed PC is automatically incremented by 1.
•Upon reset PC contents are set to 0000H and next instruction is fetched onwards.
STACK AND MACHINE CONTROL
POP Rp.(Pop register pair contents from stack).
Example
OP D(POP the content of DE pair from Stack).•
Suppose at DE pair the data is H= 20H,L= 30H SP was initialized at FFH