In the early 1990s PC memory management became a huge issue.

Eventually, PC hardware surpassed the abilities of PC software. Specifically, DOS was limited to only 640K of main memory. Yet the PC’s processor, the 386, could access up to 4MB of RAM.

Yes, that’s 4MB.

You could pack your PC with 4MB of RAM, but DOS would use only 640K. So to make the rest of the memory useful, various memory management schemes were used.

One scheme used something called high memory. That was 64K of bonus memory that could be used to load DOS itself, making more of the basic 640K of RAM available for running programs.

Another scheme was expanded memory, which was used by some DOS programs.

Then there was extended memory, which was too closely named like expanded memory to just about confuse everyone.

Extended memory was used by the 386 when it ran in protected mode. DOS ran in real mode. Protected mode was where the processor actually protected areas of memory from having one program stomp all over another one. For DOS, which ran only one program at a time, protected mode meant nothing. But DOS wasn’t the only PC operating system at the time.

Oh, yeah, there was Windows. The Windows 386 system did multitask and use protected mode. So did the OS/2 operating system. But there wasn’t much software for those two operating systems.

Technically, Windows was not an operating system until Windows 95. Before then, Windows was merely a DOS shell, or a program that ran on top of DOS. Weird, yes, but that was the late 1980s/early 1990s.

During this time, I toyed with Windows/386, and later Windows for Workgroups, as well as OS/2. But I really got work done using a multitasking utility called DESQview.

DESQview came with a memory management program I was writing about, called QEMM. (I did a bestseller for Microsoft Press called PC Memory Management back in 1990. It was the #1 computer book until DOS For Dummies knocked it off its perch in 1991.)

Using DESQview I could run multiple DOS sessions on a single 80386 computer. Unlike the primitive versions of Windows back then — or even the Mac OS — DESQview provided true multitasking. I mean, you could format a floppy disk in one window, download a file in another, and play a game in a third. Even the Mac wouldn’t let you do that, holding you hostage while a disk formatted.

DESQview used full screen text windows, not graphics. Well, actually, you could run graphics in one DESQview window and text in another. I remember running Windows/386 in one DESQview window, a DOS prompt in another, communications program in a third, and WordPerfect in a fourth. In fact, I didn’t see that level of multitasking or computer sophistication until Mac OS X came out 8 years ago.

Memory management madness continued until Windows 95 freed the PC from its memory hell. It’s a time I’m happy has passed.