From 1970 to 1975 he worked at NASA Ames Research Center where he wrote, as a part of the Pioneer 10/Pioneer 11 mission control operating system, both the telemetry monitoring and real time display of the images of Jupiter.

He joined Stanford University in August 1975 as a member of Dr. Elliott Levanthal's Instrumentation Research Laboratory.

This laboratory in conjunction with several chemists, and the Department of inherited rare diseases in the medical school made significant inroads in identifying inherited rare diseases from the gas chromatograph, mass spectrometer data generated from blood and urine samples of sick children.

His significant accomplishment was to complete a prototype program initiated by Dr. R. Geoff Dromey [3] called CLEANUP.

At Stanford in 1979, Yeager wrote the ttyftp serial line file transfer program, which was developed into the Macintosh version of the Kermit protocol at Columbia University.

In 2002 he along with Jeff Altman, then a contributor to the JXTA Open Source community, initiated the effort to establish the Internet Research Task Force (IRTF) Peer-to-Peer working group.

He has 20 US Patents issued, 4 of which are on the SIMS High Performance Email Servers which he invented and with a small team of engineers implemented, and 16 on Peer-to-peer and distributed computing.