16-bit instruction mode of 8086 and 8088 processors is called real mode. It could only address 1 MB of system memory using 20 address lines. Note that the first 1 MB byte of memory is called either the real memory or conventional memory system. Multitasking and protection are not supported. One program could be overwritten by another. All processors have real mode available. In fact, each of these microprocessors begins operation in the real mode by default whenever power is applied or the microprocessor is reset.