First post, by emendelson
The commercial dbDOS variant of DOSBox (based mostly on Megabuild, I think) claims significant speed enhancements (and something called a "live file system") in their latest version, dbDOS 4.0. The source code for the DOSBox-based part of the dbDOS system has now been posted here:
http://www.dbase.com/downloads/dbDOS_PRO_4_engine_source.zip
I don't pretend to understand the source, but I wonder whether the change in the file system is anything more than eliminating the directory cache, or whether there's anything else involved. I built the dbDOS version and wasn't able to see any specific change, except that it seemed to work in the same way that DOSBox itself works (not requiring RESCAN when changing files from Windows, not inside DOSBox itself) if you add EmptyCache after each FindFirst operation (something I didn't think up myself, of course - it was ripsaw8080 who told me about it). EDIT: ripsaw8080 actually recommended eliminating the cache entirely, not adding EmptyCache... apologies for misinformation!
It would be interesting to know what experts make of this code.