When I was considerably younger I had a Samsung SPC-3000V, an XT machine with 640KB plus an extra 128KB of RAM that could only be used for a print spooler or RAMdisk. It had a Faraday chipset, and I think it might have been based on the Juko XT (ST?) board, since I've seen similar mention of that online. I had a choice between loading spooler.exe or vrtdisk.sys to use that 128KB.
I now have a Veridata XT laptop that has a similar arrangement, and also uses a Faraday chipset. The BIOS counts to 640KB and then an extra 128KB of 'Expended' memory, as it calls it (though this can be disabled in the BIOS). MS-DOS of any version won't use this (ramdrive.sys, etc.) but DR-DOS vdisk.sys will see it and create a RAM drive. I can write data to it, and even read it back... but then a few minutes later it disappears and the RAM drive becomes corrupted.
Since this laptop can boot to DOS from ROM, I'm wondering if the memory is mapped into the ROM address space, hence the destruction (and the option to disable the 128KB in the BIOS). But before I attempt to disable the ROM (the ramdrive would be more useful on a machine with no hard drive), I'd like to try the original drivers for the chipset, specifically the RAM drive.
From searching online the Juko one was called CDISK.SYS but I'm pretty sure the Samsung one was VRTDISK.SYS. I suspect either might work.
Can anyone help?