Comment by jasomill

I was, but my application was less fun: porting Perl code from Windows NT to MS-DOS to integrate with software that required direct hardware access to a particular model of SCSI card.

Worked great, and saved a bunch of time vs writing a VDD to enable direct hardware access from NTVDM or a miniport driver from scratch.

IIRC, the underlying problem was that none of the NT drivers for any of the cards we'd tested were able to reliably allocate enough sufficiently contiguous memory to read tapes with unusually large (multi-megabyte) block sizes.