barnieg, on Thu Dec 16, 2010 1:18 AM, said:
I really should have got some sleep last night

Anyway I've got a little further than hello world with z88dk, and yes the 2 part cassette loading is a pain. What assembler are you currently using?, and have you any pointers to creating a simple assembly program? I'm posting the sample in Intellivision / Aquarius, although it would probably be better suited to an Aquarius programming subforum if we had one!
I'm using the
Telemark Assembler; a shareware version of it is bundled with the Virtual Aquarius emulator (which, to answer your other question, is generally considered to be the best emulator for the Aquarius). I didn't have another Z80 assembler handy when I began programming for the Aquarius, so I tried TASM and liked it. You'll also find source code for a few utilities (cartridge dumpers and such) in the Virtual Aquarius archive, so you can look at those as a starting point.
I don't have any "sample code" of my own to share yet, but creating an Aquarius cartridge binary in assembly is very easy. The execution of the cartridge starts at $E000, but the first sixteen bytes are used by a cartridge header, so the code needs to begin at $E010. The cartridge header is an encrypted 8-bit "scrambler code" which is ORed by the system with every byte that is read from the cartridge space; it's a very weak form of security. For testing my code, I simply copy the first sixteen bytes of the "Zero In" cartridge image (also bundled with Virtual Aquarius), which corresponds to a zero scrambler code, into the first sixteen bytes of my own cartridge image.