I assume you're not just asking about an assembler but an integrated editor, assembler and debugger. Of those three, the debugger is probably where the real work gets done. The only debugger I've used is MonAm - part of Devpac. I like it but I think it might be an aquired taste. I've got adf images of two magazine cover disks that I'd be willing to email to you if you want them. The first adf is the full version of Devpac 2 and the second is Devpac Lite (3.12). I rediscovered recently that DevLite includes a special version for 1.3.
