The address space of a processor is the total amount of memory addressable at one time. Note that the physical address space (represented by the address lines on the chip) may differ from the virtual address space (represented by the size of a pointer in the processor’s machine code). For example, the Intel Pentium Pro has a 36-bit physical address space, yet the virtual address space can vary between 1MB (the 20-bit real-mode space) and 4GB (the 32-bit protected mode space). Modern processors generally allow more than one address space to be accessed: each task might have its own separate address space, giving protection between applications.