Dave Plummer

There's no graphical interface.

Now, Microsoft did add a text-based graphical interface for things like an editor and QuickBasic.

in DOS 5, I believe, and it was a DOS shell, which was sort of a graphical file manager in MS-DOS 4.

So they experimented with it, but it's largely a command prompt.

Well, it was limited by the original x86 instruction set, which limited it to 640K.

And then there were various band-aids on top of that to do high mem and then extended memory beyond that.

And a lot of hoops have to be jumped through to make anything work without consuming base RAM.

Yeah, 640k is the maximum that's ever going to be available.

So it's not what's available to you as an operating system developer because whatever you use is what the user won't get.

So if you use 10k needlessly, every machine in the world now has 10k less.

So it's kind of a big responsibility.

Nobody will ever need more than 640k?

One of the first things I did was to take SmartDrive, the disk cache, because I had familiarity with disk caches, and to add CD-ROM caching to it because I was new.

CD-ROMs were just coming out.

Microsoft Bookshelf was one of the few products you could run for it.

And as you can imagine, caching a CD speeds it up by dozens of times if you're smart about it.

So it was a big performance win and a nice thing to work on.

A bigger part of that was moving a bunch of smart drive and eventually the double-spaced compression engine up into what's known as high memory.

And without rat-holing on the technical aspect of it, on the XA6, there's something I believe called the A20 line.

And I probably have this backwards, or I got a 50-50 shot at it, but...