Windows 3.x must have 2048k minimum to run in 386 Enhanced mode.

Shadow RAM is done in extended memory between the 640K boundary and 1 Megabyte boundary. Shadow RAM improves overall performance of the computer and can increase system speed up to 400%.

Shadowing copies slower essential ROM memory into RAM for faster access speeds. The original address associated with ROM drivers are typically disabled.

Expanded memory involves mapping addresses of logical pages to physical pages. Expanded memory was originally designed for motherboards prior to the 286. EMS was designed for 8-bit systems and cannot access Extended Memory. EMS is rarely utilized in modern systems.

The unused spaces in upper memory can be divided into blocks and are known as upper memory blocks (UMB). These empty blocks have no RAM associated with them and are just reserved space.

In protected mode the memory is protected in the sense that a program can only write to the memory allocated to it. In addition, this mode allows for multitasking programs.

The MEMMAKER utility is used to modify the system's CONFIG.SYS and AUTOEXEC.BAT files so that device drivers and memory resident programs take up less conventional memory space.