In my journey along the asm learning trail, I have been listing the effects of b_calls on the various registers. Having listed a few of the most-used, along with their Romcall addresses, I am amazed that many Romcalls are only 3 bytes long. Since the last byte must be 'ret'. it doesn't appear to leave much for any serious code. (unless it calls yet another routine) It would be interesting to examine a list of disassembled Romcalls. Is such a list available ? Failing that, it should be relatively simple to examine the contents of Romcall addresses and disassemble them manually. as a matter of interest, in the old days of the Commodore64, there was available a cartridge which would merrily disassemble machine language.

Generally ROM calls do indeed call another routine. The reason for this is so that the actual routines can be expanded or shrunk in OS updates without having to change the addresses of the ROM calls, which would mean breaking compatibility with all programs made for previous OS versions.

There isn't really a place to look for disassembled code (I believe the OS license agreement specifically forbids reverse-engineering it or something to that effect), but you can check out BrandonW's Pterodactyl utility with the IDA disassembler. (Unfortunately, IDA isn't free.)

That does make a lot sense, I'm chuffed that I thought of the possibility.