Maximum mode is one of the two hardware modes available to the Intel 8086

Intel 8086

The 8086 is a 16-bit microprocessor chip designed by Intel between early 1976 and mid-1978, when it was released. The 8086 gave rise to the x86 architecture of Intel's future processors...

 and 8088

Intel 8088

The Intel 8088 microprocessor was a variant of the Intel 8086 and was introduced on July 1, 1979. It had an 8-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers and the one megabyte address range were unchanged, however...

 processors (CPU

Central processing unit

The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...

). The other is minimum mode

Minimum mode

Minimum mode is one of two different hardware modes of the Intel 8086 and 8088 processors . The other is maximum mode. Mode selection is accomplished by how the chip is hard-wired in the circuit. Specifically, pin #33 is used to select the mode, depending on whether it is wired to voltage or to...

.

Maximum mode is for large applications such as multiprocessing

Multiprocessing

Multiprocessing is the use of two or more central processing units within a single computer system. The term also refers to the ability of a system to support more than one processor and/or the ability to allocate tasks between them...

. The mode is hard-wired into the circuit and cannot be changed by software. Specifically, pin #33 (MN/MX) is either wired to voltage or to ground to determine the mode. Changing the state of pin #33 changes the function of certain other pins, most of which have to do with how the CPU handles the (local) bus

Computer bus

In computer architecture, a bus is a subsystem that transfers data between components inside a computer, or between computers.Early computer buses were literally parallel electrical wires with multiple connections, but the term is now used for any physical arrangement that provides the same...

. The IBM PC

IBM PC

The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12, 1981...

and PC/XT use an Intel 8088 running in maximum mode.
http://www.8085projects.info/post/Maximum-Mode-Interface.aspx