1) It's the needed attitude that gave TCH the information he needed to start using his Atari instead of posting messages in a forum. He is now heading in exactly the correct direction.
2) You are so wrong. DOS must ALWAYS be booted so as to be present in order to write/read files - there is no workaround for this, go back to school. At least re-think this aspect - it is a DOS boot that places entries in the HATABS table that allows for disk PUTBYTE and GETBYTE functions to work even in BASIC.
Atari Artist does NOT have DOS in the cartridge - no DOS means no disk file access period.
It is that simple and TCH needs to know that with the very first step. He needs someone to send him a working DOS boot disk so he can start using his Atari, there is no way around this.
What you are trying to say is that not all disks need to have DOS boot files on them which is true. And such a disk can be used to store files - but this same disk can not be used by any Atari computer that did NOT boot up with a DOS boot disk...