Digimon Tamers 1984 was a short story written as a prequel to Digimon Tamers and originally published in Volume 5 of SF Japan in 2002.
It was written by Chiaka Konaka who did the series composition for Tamers ("writer in chief" as he's translated to English a number of times.) In addition it has illustrations by Kenji Watanabe, longtime Digimon designer.