Also known as "manually pumping the message loop". I'm almost certain that that program was handling communications events on the same thread as the message pump, and only relying on a very slow timer to move them through. There was probably plenty of such badly-written software back then, because 16-bit Windows was cooperatively multitasked and had no concept of threads.

Related article and discussion:

https://news.ycombinator.com/item?id=625957

http://web.archive.org/web/20140105042459/http://support.mic...