Harry Stewart was a contractor for Atari from August 1978
through October 1983. He contributed to the operating system design
and the manuals for the Atari 400 and 800; created the Atari
implementation of the WSFN language (which was released in the
first Atari Program Exchange catalog, summer 1981). He worked on
Atari's PILOT programming language and the unreleased sequel, Super
PILOT (also known as Summer Camp PILOT.)
Harry saved an enormous amount of material: source code,
memos, notes, and more. He scanned some of it, I scanned some of
it, and it's online at the Internet Archive at the AtariAge
forums.
This interview took place on June 29, 2017.
"You debugged in your head. It wasn't sitting at the machine
single-stepping and doing breakpoints. If you had a problem, you
thought it out. Why is this happening? ... Working on the hardware
only as necessary."