The Bob Moog Foundation has a post by Dale Ong covering his work with the prototype Moog modular, as Bob Moog's tech at Big Briar. Click through for the full post.
Pictured: Dale Ong, Bob’s synthesizer tech at Big Briar, Inc., with the prototype Moog modular, 1982.
"The instrument itself was comprised of three units. A small vertical cabinet housed two voltage controlled oscillators, two voltage controlled amplifiers, and a power supply. These were the oldest of the modules and had a distinctly handmade look to them. Controls were identified with labels printed on heavy card stock which were glued to the metal panels. Next was a small horizontal cabinet which held a low-pass filter, a band-pass filter, a noise generator, a trigger extractor, an ADSR envelope generator, and a second power supply. These were newer and sported the form which would later become so familiar to users of the 900 series modules. The third unit was a dual keyboard with built in envelope generators. All in all, it was not particularly impressive looking – If you were not aware of its history, you would never know how important this synthesizer was."