HIMEM.SYS - Computer Definition
An extended memory manager that has been included with DOS and Windows, starting with DOS 5 and Windows 3.0. It allows programs to cooperatively allocate extended memory in 286 and higher PCs. HIMEM.SYS is an XMS driver. Starting with Windows 95 and subsequent 32-bit versions of Windows, HIMEM.SYS was automatically loaded at startup. See XMS.