the difficulty with a large assembly project is that you have to write a lot of well-named and well-designed macros and subroutines and otherwise create your own modularizations, otherwise it will be completely unmanageable. the main difficulty in my case though was having to interface to multiple devices, one of which was designed to be networkable (ie pain in the ass protocol,) something with which the language didn't help
That's where you fail. The first thing we learnt about assembler was this - write in assembler, do not invent your own language and write in that language. If you do so, nobody will be able to read your program but you.
It sounds like you went and implemented your DSL on top of assembler, which is really bad practise.
