@ellyse @inverseatascii What I used at the time was Atari MASM and BUG, the primitive ancestor of BUG65.

Also I often just wrote my ASM on paper, converted the opcodes & bytes to ATASCII chars (see chart), and typed them in BASIC as A=USR("hxxx"). This works but it's insane.

DDT seems "better" than BUG*, but I hate that it sits on Page 6 so much.

Disk version of Mac65 seems good, the zip at
https://www.atarimania.com/pgesoft.awp?soft=10965
contains an ATR file of JUST Mac65 & Bug65, and OS/A+.
#atari #retrocomputing

@ellyse @inverseatascii The Atari Assembler was written in '78-79 alongside the original Atari BASIC. Both are pretty buggy, but worked and were small enough to go on an 8K cartridge, work with cassette if needed.

OSS was some of that team who made improved versions, which became OS/A+, MAC/65, BASIC XL, etc.

Atari's own tooling was MASM, which like all their in-house software was meant to use 2 disk drives and fully loaded machines, and they couldn't figure out why it didn't sell well.