You can use a ISA XMS/EMS memory card like the AST Rampage - but they are not much easier to get, at least one with drivers...

Hm. EMS cards can be had easily. Lo Tech, Sergey Malinov and others have designed them. But I think that Windows 3.0/3.1 do not support EMS, right? IIRC they need raw protected mode access to the extended memory.

root42 wrote:

Hm. EMS cards can be had easily. Lo Tech, Sergey Malinov and others have designed them.

Yes, I heard positive feedback about these. I *think* the smartness of these new cards relies within the driver.
AST Rampage and others went far beyond to what final EMS 4.0 provided (EEMS).
Advanced EMS features were used excessively by DesqView and Multi-Tasking DOSes.
I'm really curious, how well that LoTech board would perform on them! I'd be cool if someone would do the experiment. 😀

root42 wrote:

But I think that Windows 3.0/3.1 do not support EMS, right? IIRC they need raw protected mode access to the extended memory.

That's a complicated matter. In simple words, as far as I understand:
a) Windows 3.1 doesn't use EMS for its own. However, It will emulate EMS for DOS programs (Enhanced Mode) or allow existing EMS drivers to stay (Standard Mode).

b) Windows 3.0 behaves the same except for Real-Mode. In RM, it will use EMS to enlarge physical memory.
It will allow large Windows 2.x and 3.x programs to run as if there was ordinary (XMS) memory available.
On Windows 3 in RM, Windows programs do not have to be EMS-aware to benefit from that.
With EMS beeing available, Windows 3.0 allows the use of wallpapers even in Real-Mode.
So on a PC/XT, an EMS card could make Windows 3.0 kinda usable, because there's enough RAM left for user applications.

c) Windows 2.x can see existing EMS memory. But can't give it to Windows programs.
Some EMS-aware DOS or Windows programs may use the extra memory provided by EMS.

d) Windows /386 can emulate EMS memory. It uses it to enhance DOS multi-tasking support (swap to disk, printer spoolers etc).
Like Windows 2.x, it can't provide that extra memory to normal Windows programs. They still run in a tiny, separate Windows-VM (running WIN86.COM).

Sorry, that's all I know. We had a discussion about this in another thread a while ago.

Windows 3.1 on a 386 with 640K RAM - Possible?

Also loosely related to that:

Is it possible to go over the 640KB barrier on an 8088 using some software ?
What am I doing with a 286?

Ok, thanks for all your replies. I thinkt for this build, I will stick with 1MiB of RAM, since more RAM usually only helps with Windows, or a few DOS applications. For my 386 build this will not be needed after all.

I will still have a search for 421000 DRAM chips on eBay, just in case... 😉

421000 is NEC's part number. Other vendors call it 511000 or 41C1000.

yuhong wrote:

421000 is NEC's part number. Other vendors call it 511000 or 41C1000.

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Thanks! I will add that to my search.