MagnaRAM

Quarterdeck Expanded Memory Manager (QEMM) is a memory manager produced by Quarterdeck Office Systems in the late 1980s through late 1990s. It was the most popular third-party memory manager for the MS-DOS and other DOS operating systems.

The principal competitors of QEMM were BlueMax/386MAX, and HeadRoom/NetRoom from Helix Software Company.

Compaq DOS 3.31, released in November 1987, was the first DOS operating system to bundle technology similar to QEMM-386, incorporating a 386-mode EMS manager called CEMM. QEMM was the first V86 memory manager on the market.

QEMM provides access to the Upper Memory Area (UMA) and memory through the Expanded Memory Specification (EMS), Extended Memory Specification (XMS), Virtual Control Program Interface (VCPI) and DOS Protected Mode Interface (DPMI).

It relocates DOS kernel, COMMAND.COM interpreter, DOS resources (e.g.: buffers, file handles, stacks, lastdrive). It supports DOS 3.2 or higher.

It allows drivers to be loaded before loading QEMM and still allow the use of QEMM's Stealth feature.

It was a virtual memory compression utility for Windows 3.1, Windows For Workgroups and Windows 95. MagnaRAM is included with QEMM 97.

MagnaRAM was also released as a separate utility.

MagnaRAM worked by replacing a portion of Windows' virtual memory system. MagnaRAM would insert itself in the string of Windows Programs that determined what pieces of RAM will be moved to the hard disk. Instead of writing directly to the hard disk, the information to be written would go to MagnaRAM's own buffer as this was a faster process. During CPU idle, MagnaRAM would compress the information in its own RAM buffer. When the RAM buffer becomes full, it is then swapped to the hard disk taking both less time and less space.

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