Re: [Freedos-devel] New freeware DOS memory manager: EMS Magic

[Liam P. <lp...@gm...>]

On Tue, 21 Jan 2025 at 22:06, David Schwab via Freedos-devel
<fre...@li...> wrote:
>
> From memory, XMS was earlier, and it required both a driver and an external memory card. I believe you could go as high as 8 MB. I can't recall the processor requirements, but I know EMS required at least a 386. Most programs, and most technical programming books I had (like Norton) used EMS almost exclusively. Most of the magazines I still have from that era, like PC Magazine, seem to focus more on HMA and EMS, likely because DOS focused more on those than XMS.

You have it backwards.

EMS is short for Expanded Memory. It works with hardware from an
8088/8086 upwards. On a 386 it can be done entirely in software and
that is what MS's EMM386 does.

https://en.wikipedia.org/wiki/Expanded_memory

Because of this it's widely supported in classic DOS apps from before
the Windows 3 era (which began in 1990).

XMS is short for eXtended Memory. It is available in DOS from the
80286 upwards. It just means "memory over the 1024 kB address". There
is no way to access it directly from DOS but the HIMEM.SYS driver
added an API to manage it. HIMEM.SYS needs a 286 or better.

https://en.wikipedia.org/wiki/Extended_memory

Few DOS apps can use it, but from the 1990s onwards, you could write
286 or 286 apps for DOS using a tool called a "DOS extender". They
cost money per copy, and your apps wouldn't work on an 8088/8086, or
under some other OSes, or under some DOS memory managers.

https://en.wikipedia.org/wiki/DOS_extender

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