Harry Potter wrote on 2025-12-18, 19:32:

I believe that needs to be done via msdos.sys, but you can also get your desired options by pressing F8 while Windows is starting up.

Ah, I see. But yeah, the options are there with F5 and F8.

I still seem to be struggling at getting to grips with the ins and outs of EMS, XMS, and UMBs etc. I did read some articles/pages about them and how they work, though I’m still a bit confused with certain aspects.
For instance, installing Wolfenstein 3D, and trying to load it, it gives me a box saying that it needs more conventional memory, and for me to use a memory manager, like EMMS. However, with my custom boot menu set up the way it is, I’m getting that warning with EMMS386. So I have HIGHMEM, EMMS386 and UMB. Every time I check the memory though, it always lists my Upper at 0. And that’s with having my CD driver set to DEVICEHIGH.
With XMS, the game loads. There’s only a tiny bit more Conventional Memory than with EMS though. I think it’s gone from 512…? To 572K. So I’m confused as to what’s going on. Why, despite having EMS and Upper Memory enabled, the game won’t load, and why my Upper is always at 0. Or am I supposed to set a specific amount in the config file? At the moment it’s just DOS=UMB.

Thanks

Doesn't sound like you have emm386 set for UMBs at all.

Try at least this in config.sys:
device=c:\dos\himem.sys
device=c:\dos\emm386.exe noems highscan
dos=high,umb

The add LH in front of any drivers in autoexec.bat and in config.sys use devicehigh= for anything that's not himem or emm386

To understand PC memory and architecture, It helps to know "Where it came from", and why...

"In the beginning" computers were large rooms filled with racks of electronics, all connected to a "van sized" box full of electronics called the "Central Processor". Processors are classified by "bits" meanoing how many digital "bits" of data can be manipulated in one "cycle". These mainframe systems were often 32, 40, 64, 96 or more "bits".

IBM was a well known maker of these "Big Iron" systems.

As semiconductor technology improved, the needed circuitry could be made smaller, till a company "Intel" decided they could put a limited edition of a proceesor into a single-chip "microprocessor".

The first Intel offering was the 4-bit 4004. Very limited, I don't recall any significant functionality computer using the 4004 .. but it was a game changer in that it showed the ability to "program" functionality instead of hard-wireing...

There next offering was the 8-bit 8008. Much more capable/powerful, you can experience an 8008 computer via my MOD8 simulator.

Then Intel made the 8-bit 8080, more powerful and had a 16-bit memory "Address bus" which allowed it to have 64k of memory. Now enough to make a "real" computer, amd Ed Roberts of MITS created the "Altair" - considered by some to be the first "Personal Computere". You can experience it with my Altair simulator.

Then Intel made the 16-bit 8086 - kept similar to the 8080 to ease converting software. To allow more mamory, the address bus was expanded to 20 bita (1M).

IBM noticed and chose the 8086 to make the "IBM Personal Computer" - the early PC.

To keep it more 8080 like, Intel had introduced the concept of memory "segments" 16-bit registers which make the top 16-bits of the 20-bit memory address. This allowed the processor to still "logically" use 16-bit memory addressing but it could be moved aroung to any 16-byte boundary in the 1M 8086 address space.

There were separate segments for Code, Data and Stack as well as an Extra one for other cases where the code had to go outside it's available memory.

In the original 8086, memopry addressed computed as (segment*16)+Offset which happened to exceed 20 bits (can be as much as 64k-16) wrapped aroud to offset from 0. As still more advanced proceessors had "protected mode" and supported more than 1M of RAM, this became "confusing" - some CPUs would still wrap real mode addressed to offsets from 0, some would flag an error-interrupt, and some would allow access to the (64k-16 bytes) of memory ABOVE 1M ...

There's also Bill Gates famous quote "640k ought to be enough for anyone", about MicroSofts decision to limit DOS to 640K consegutive memory, with I/O devices etc. mapped abote.

Some systems could map actual memory into the area above 640k, and this along with the (64k-16) bytes accessable above 1M became known as various types of "High" memory. And given that there was no official standards on how to allocate or manage it, various "high memory" software drivers became common and required.

And... with more advanced processors and hardware which could be comfigured to access other memory above 1M - systems/drivers were defined to create XMS, EMS etc.

I hope this helps a little ... I've not gone into details, but knowing how it came to be might help understand specifics as you discover them.