The most you can cram on a DD floppy

[Tomas]

It depends on how efficient the orginal data is packed. You can probably get like 10megs onto a single floppy if you compress a non compact txt file. If you compress a file that is already using a compressed format like a mpeg, divx, mp3 and so on, then you will most likely not be able to gain more at all by compressing it into zip, lha or so on..

[Tomas]

I already tried powerpacking all the large executables before adding them to the lzx archive, but surprisingly it made the lzx archive BIGGER. I guess the lzx compression works better on non-powerpacked files. I wouldn't even attempt to use a newer compressor like "RAR" because the unrar executable is a whopping 180K and uses huge stack and RAM to extract.

There is pretty much nothing to gain on compressing something that has already been compressed with something else.