The first publicized (ie, in print
written for the TRS-80
series of computers made by Tandy
in the early 80's
Bullet-80 was designed to run to a TRS-80 Model III with 64K of RAM and upto four 180K 5 1/4" floppies. It contained a message forum with threads and searching, a download area with upto 500 files and a built-in display interrupt driver that linked all output to the screen to the serial port.