What are Instructions?

Instructions

An instruction is a command to the processor. It is usually very simple, such as 'Jump to the line labeled "DisplayHello"', 'load the a register with the value 7' or 'add the contents of the a and b registers together and store the result in a'. However, these instructions must be written in assembly, rather than English.

Example Instructions

There are hundreds of different instructions in assembly, for example:

Sample_Instructions:
  jp DisplayHello     ; Jump to label DisplayHello
  ld a,7              ; Load a register with 7
  add a,b             ; a = a + b

  inc c               ; c = c + 1
  ld hl,$1234         ; hl = $1234
  call _clrScrn       ; ROM call - clears screen
  or b                ; a = (a or b)
  ld (MyLoc),a        ; memory[MyLoc] = a
  ret                 ; return from routine / prog

These instructions will be looked at in more depth later.