...which seems to imply that you're going to need a more efficient language than "traditional" C/C++ if you want to fit more functionality on a single floppy, although given that early UNIX was written in C/Asm, I wonder how much of it is due to bloat/unnecessary/extra abstraction than the choice of language itself.
QNX 4 was mostly written in C and the demo disk fit on a single floppy and included the whole system including a TCP/IP stack, drivers for a few common network adapters, a GUI, a web browser (with javascript), and various demo applications.
Granted, I think it's probably easier to limit size (and more importantly, complexity) by using assembly language, it's by no means necessary. Lately I've been exploring minimizing complexity by using less-capable text editors like ed and notepad.
...which seems to imply that you're going to need a more efficient language than "traditional" C/C++ if you want to fit more functionality on a single floppy, although given that early UNIX was written in C/Asm, I wonder how much of it is due to bloat/unnecessary/extra abstraction than the choice of language itself.