TS-UGOS 4

TS-UGOS 4 (codenamed Sydney) is a graphical operating system developed and released by Theorysonic. It was released on May 11, 1991.

History
The development of TS-UGOS 4 began on April 25, 1989, thirteen days after the release of TS-UGOS 3.

New features

 * Rounded taskbar.