I actually went down to the basement and dug out my old notebook. DOS 3.3 Fast Load Enhancement, by Thomas N. Burt (author of HyperDOS) 1983 Nibble Vol 4 no 5 p48+. It was pretty much as I remembered in my previous post. Comparison-load 93 sector Applesoft program Regular DOS - 23 secs, Fast Load DOS - 5.5 secs. The article in great detail documents DOS shortcomings, how it only reads one sector per rotation. The great optimised sector interleave was botched in the file manager. After the mod, it reads 8 sectors per rotation. So raw data access is increased 8 fold. WIth other file handling overhead, the total increase is from 2 to 5 fold, with longer files giving the greatest increase. This performance increase would be seen with LOAD,RUN, BLOAD, and BRUN commands. The patch was about 200 bytes, replacing INITs low-level format code. It was a very worthwhile patch. Of course with emulators, it doesn't really matter. I wonder what the copyright status is for Nibble programs. I know at one time there was a provision in copyright law that after 20 or so years the rights would revert to the original author.