«

[natas]

In case you have not enough memory in the lower 640K range the russian PTS-DOS could be a good choice. It's written in 100% assembler language and very fast. In MAX MEMORY MODE it gives you 640K free RAM after booting. It's commercial, but there exsists a demo version which is fully functional with only a 10 second delay at boot time. It has CDROM support without extra needed drivers like MSCDEX.EXE.

I have the commercial version with full sources including the fully functional demo. If you want to try, but cannot find the demo on the net anymore PM me, and I'll send it to you.