Summary based on entries from the Star Trek Memory-Alpha site and elsewhere:
Stardate was originally published by FASA. Its subtitle called it "The Magazine of Science Fiction and Gaming", but it focused almost exclusively on the FASA Star Trek Role Playing Game and its supplements.
Issues 8 to 11 were published by Associates International, Inc. and the coverage expanded to other RPGs and table-top games, fiction and comic strips. The magazine's subtitle became "The Multi-Media Science Fiction Magazine".
Volume 3 was published by Reluctant Publishing, Ltd. and started focusing more on Battletech and less on Star Trek. The subtitle changed again, becoming "The Science Fiction Gaming Resource" to reflect its expanded coverage of role-playing and fighting games. This run lasted 6 issues.
By 1988, the magazine would change its name to StarDrive, Volume 1 Issue 1. This was the first and last issue published, as Reluctant Publishing went out of business.