8085 Microprocessors Notes

Statement : Find the sum of the series of numbers. The length of the series is given in the memory location 2000H and the series itself begins from memory location 2001H.  A). If the sum is an 8-bit number, store the sum at memory location 2005H.  B). If the sum is a 16-bit number, store the sum at memory locations 2005H and 2006H. A).   EXAMPLE : (2000H) = 04H (2001H) = 30H (2002H) = 15H (2003H) = 13H (2004H) = 33H Result = 30H + 15H + 13H + 33H = 8BH Therefore, (2005H) = 8BH FLOW CHART : PROGRAM :               LDA 2000H          ; Get the length of the series               MOV C, A            ; Initialise counter               SUB A                  ; Make Sum = 0               LXI H,...

EI: This instruction is used to set the interrupt enable flip flop so that all maskable interrupts are enabled. After an interrupt is acknowledged, the interrupt enable flip flop is reset. This instruction is used to re-enable the interrupts. OPERATION : IE (FF) = 1 No flags are affected. It is a one byte instruction. Implied addressing mode is used. DI: This instruction is used to reset the interrupt enable flip flop so that all maskable interrupts are disabled. This instruction cannot disable TRAP since TRAP is a non-maskable interrupt. OPERATION : IE (FF) = 0 No flags are affected. It is a one byte instruction. Implied addressing mode is used. NOP: This instruction shows that no operation is performed. OPERATION : PC = PC + 1 No flags are affected. It is a one byte instruction. Implied addressing mode is used. HLT: This instruction is used to halt the processor. The processor can be restarted by a valid interrupt or by applying a RESE...