Electronic – How to set all flags in 8085

Ah, more computer archaeology! I'm just going to give you a solution here, since it would take too long to address the misconceptions in your code. Study it and make sure you know exactly what each instruction is doing and why.

        ;; HL points to array of bytes to be added
        ;; DE contains 16-bit sum
        ;; C is loop counter

        lxi     h, 4500h        ; point to first byte
        mov     e, m            ; fetch first byte
        mvi     d, 0            ; clear high byte of sum
        mvi     c, 5            ; add 5 more bytes
loop:
        inx     h               ; point to next byte
        mov     a, m            ; fetch next byte
        add     e               ; add to sum
        mov     e, a
        jnc     skip            ; if carry ...
        inr     d               ; increment high byte of sum
skip:
        dcr     c               ; decrement loop counter
        jnz     loop            ; repeat if not done

        ;; Store the result
        xchg                    ; move sum to HL
        shld    3000h

        hlt

Basically you read the processor's databook, which will tell you how it starts executing, and design the board so that the ROM is mapped to the appropriate address.

For example the Z80 will assume whatever it finds at address 0000 is a valid instruction and execute it. So, when resetting a Z80 after power on, you should map the ROM to address 0 and put your startup code there.

Later, you can map the ROM to another address or even select it out of the memory map altogether, but before you do that, typically you would load an actual OS like CP/M from floppy disk, into RAM, map the RAM to address 0, and either warm reset or simply jump to 0.

Other CPUs may start up in different ways, the 8086 starts at address FFFF0, but all have in common that their documentation tells you where this first instruction or Reset Vector is located.