Register Section of 8085
At first we will see some important configuation of 8085 Accumulator - 8bit
data bus - 8bit
address bus - 16bit
program counter - 16bit
stack pointer - 16 bit
BC DE HL - Each has 8bit (by pairing they perform as 16 bit)
>> Accumulator : Accumulator 8 - bit register ,used to perform Arithmatic(Addition, Substract..etc) and Logical Operation(OR, AND , NOT..etc) .It is used to store the result of these operation.
>>GPR(General Purpose Resister) : The 8085 has six 8 bit GPR , name B,C,D,E,H,L. Thay used for storing the operands> Temporarely during the execution of the instruction . These resgister can be used single or can be concatenated to form three 16 bit register B-C, D-E, H-L, while storing 16 bit in the register payer the higher order byte of the data/address is store in the first register(b/D/H) and lower order data/ address is store in the second register(C/E/L)
>> SFR(Special Function Register) :
- FLAG register (8-bit) : Flag register is used for storing significant information regarding the final result of an instruction . This informations are used for decision making.
The informations are store in the 5 bit o the register in the form of FLAG. while the other 3 bits insignificant . The significant bit or flags are - (i) Sign flag (ii) zero flag (iii) Auxulary Carry Flag (iv) Parity flag (v) carry flag
(i) Sign Flag : If the final result store in the Accumulator in Negetive . Then sign flagis set(S=1), other wise (positive) sign flag is reset(S=0).
(ii) Zero Flag : If the final result obtain after execution of an instruction is Zero then the zero flag is set(z=1)
(iii) Auxulary Carry Flag : Auxulary flag is set if an overflow occure out of B 3 of an Accumulator. It is used in BCD(Binary Codded Decimal)
(iv) Parity Flag: If the number of ones after execution in the accumulator is even then parity flag is set.
(v) carry Flag: When over flow occures out of B7 and borrow is occur then CY or carry flag is set.
>> rogram counter : It is a 16 bit register. Which is used for holding the address of next instruction to be executed in a program sequence . The processor update the precontain Automatically .After it has fetched one instruction for execution.
>> Stack Pointer : Stac Pointer is usually an array of memory location in the Ram which are used for storing temporary information in LIFO manner .
Stack Pointer is decremented s time data is pushed into the stack and is incremented is type when data is popped or removed from the stack.
