"This is a 4K byte program for assembling machine code
programs. It comprises 3 distinct parts: 1) a full symbolic 2 pass assembler 2)
a symbolic disassembler 3) a text file editor The ADE requires an Acorn
Operating System for handling keyboard and VDU.
Source code (ca65 format)
For those with disc based Systems here is an .ssd image containing ADE: