Yesterday I received a nice IBM PS/1 486 tower , model 2168-552. This system uses the VLSI 82C480 chipset (datasheet download) :
supposedly The Last Byte supports it and have it on it's list but auto-detection fails and if forced to use it the system freezes.
I can see the UMB area is mostly not used - plenty of space for ram to exist there. Obviously I want to create and use UMB blocks without using EMM386 or a similar EMS memory manager.
If anyone has an idea or suggestion please comment, thanks!