public static boolean isHigher8BitRegister(final String register){
  return register.equals("ah") || register.equals("bh") || register.equals("ch")|| register.equals("dh");
}

public static boolean isHigher8BitRegister ( final String register ) { return register . equals ( "ah" ) || register . equals ( "bh" ) || register . equals ( "ch" ) || register . equals ( "dh" ) ; }
determines whether a passed register is either ah , bh , ch , or dh .
