Kaypro Micro 1

Serial Numbers I've seen:
Earliest	475947
Latest	475947
First Marketing	Q3 1988
First Shipping	Q1 1989

"Kaypro also announced yesterday the Micro I, which the Solana Beach company said is the "world's smallest desktop computer system." The machine, which has a 12-inch by 12-inch footprint, is targeted for use as a low-cost node in local area networks."
(Craig D. Rose, Staff Writer, "Kaypro finds cost-savings source of chips", Newspaper Clipping might be from the San Diego Union)