Branchng Group Instruction , 8085 programming



)Branching, 
The branching instructions alter normal sequential program flow, either unconditionally or conditionally. The unconditional branching instructions are as follows:

JMP Jump
CALL Call
RET Return

Conditional branching instructions examine the status of one of four condition flags to determine whether the specified branch is to be executed. The conditions that may be specified are as follows:

NZ Not Zero (Z = 0)
Z Zero (Z = 1)
NC No Carry (C = 0)
C Carry (C = 1)
PO Parity Odd (P = 0)
PE Parity Even (P = 1)
P Plus (S = 0)
M Minus (S = 1)

Thus, the conditional branching instructions are specified as follows:

Jumps Calls Returns
C CC RC (Carry)
INC CNC RNC (No Carry)
JZ CZ RZ (Zero)
JNZ CNZ RNZ (Not Zero)
JP CP RP (Plus)
JM CM RM (Minus)
JPE CPE RPE (Parity Even)
JP0 CPO RPO (Parity Odd)

Two other instructions can affect a branch by replacing the contents or the program counter:

PCHL Move H & L to Program Counter
RST Special Restart Instruction Used
with Interrupts

Stack I/O, and Machine Control Instructions:
The following instructions affect the Stack and/or Stack Pointer:

PUSH Push Two bytes of Data onto the Stack
POP Pop Two Bytes of Data off the Stack
XTHL Exchange Top of Stack with H & L
SPHL Move content of H & L to Stack Pointer

The I/0 instructions are as follows:

IN Initiate Input Operation
OUT Initiate Output Operation

The Machine Control instructions are as follows:
EI Enable Interrupt System
DI Disable Interrupt System
HLT Halt
NOP No Operations
e) Miscellaneous
i)  STACK
the stack is defined as a set of memory location in R/W memory specified by a program in main memory these main memory are used to store binary information temporarily during execution of the  program. The beginning of the stack in the  program by usin g the  instructin LXI SP,!6 bit address.
Once the stackj  location has been defined it loads the 16 bit address in the stack pointer register.
Some left
ii) Push RP/PSW
·         Store content of register pair in the stack
·         1 byte instruction
·         Copies the content of specified register pair or program status word i.e. PSW, accumulator and flag an the stagment
·         Stack pointer is increment and the content of higher order register is copied .Then it is again decremented and content of lower order is copied. 
iii) POP RP/PSW
retrieve register Pair from stack
1 byte instruction register pair or program status word
Lapes the content of the top to memory locations on the stack into specified register pair or program status word.
 Content of memory location indicated by the SP is copied into low order register and sp is incremented by 1figure ok …………….
Then the content of memory locationspecified by sp is copied into high order register and sp is incremented by one .


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