The 8086 processor provides a 16 bit data bus. So It is capable of transferring 16 bits in one cycle but each memory location is only of a byte(8 bits), therefore we need two cycles to access 16 bits(8 bit each) from two different memory locations. The solution to this problem is Memory Banking.

It is a 16 bit µp. 8086 has a 20 bit address bus can access upto 220 memory locations ( 1 MB) . It can support upto 64K I/O ports. It provides 14, 16-bit registers.

The 8086 uses 20-line address bus. It has a 16-line data bus. The 20 lines of the address bus operate in multiplexed mode.

In this we can connect more processors to 8086 (8087/8089). 8086 max mode is basically for implementation of allocation of global resources and passing bus control to other coprocessor(i.e. second processor in the system), because two processors can not access system bus at same instant.

Maximum Mode 8086 System In the maximum mode, the 8086 is operated by strapping the MN/MX pin to ground. In this mode, the processor derives the status signal S2, S1, S0. Another chip called bus controller derives the control signal using this status information.

Register addressing mode- This addressing mode is normally preferred because the instructions are compact and fastest executing of all instruction forms. Registers may be used as source operands, destination operands or both.

DS (Data Segment) : is used to hold the address of currently active data segment. 3. ES (Extra Segment) FS, & GS : are used as general data segment registers. These registers hold the base addresses of three different memory segments.

Paging behavior is controlled by the following control bits: The WP and PG flags in control register CR0 (bit 16 and bit 31, respectively).

The maximum segment size was 64 Kilobytes. In the Intel 80386 and later processors, protected mode retains the segmentation mechanism of 80286 protected mode, but a paging unit has been added as a second layer of address translation between the segmentation unit and the physical bus.

The size of the descriptor table is subtracted by 1 because 65535 is the maximum value for size but the GDT can only be up to 65536 bytes (which means that the entries can be maximum of 8192). Also, no GDT can carry a size of 0. Step-3 : The GDT contains 8-byte entries, each having a complex structure as follows.

Minimum size of a segment can be 16 bytes and the maximum can be 64 kB.