As one might expect, this cartridge is Atari's assembly language environment. Individuals who knew assembly language could code in this environment.
The Atari Assembler Editor cartridge was a program used to edit, compile and debug assembly language programs for the Atari 8-bit computers. It was programmed by Kathleen O'Brien of Shepardson Microsystems, Inc.
The program was a two-pass 6502 assembler, in an 8KB cartridge. It was the first commercially available assembler for the Atari 8-bit computers.
Upon bootup, the cartridge started up in EDIT mode. The programmer would enter assembly source into the editor using the full-screen features on the Atari. All source had to be prefixed with a line number, or it would be interpreted as a command. Due to limited cartridge space, errors were reported with error codes.
Finally, the code was assembled by typing in the ASM command.
The Atari Assembler Editor featured a debugger. This mode was entered by typing in the command BUG at the prompt. The debugger allowed the viewing and changing of registers and memory locations, perform a trace, single-step and disassembly.
The programmer went back to the EDIT mode by typing X at the command prompt.
Disadvantages of Atari Assembler Editor were speed, bugs, lack of macros and awkward conditional assembly features. Unfortunately, the program used the Atari's floating point routines for arithmetic calculations, greatly impacting performance. The debugger was really a monitor, limited in power and flexibility. Nonetheless, it was the only available Atari assembler for many programmers.