SVR1 【UNIX System V Release 1】
full spelling ： System V Release 1
SVR1 is the first version of UNIX System V. It is also known as System V.0 or System V Release 1. SVR1 was developed by AT&T's Unix System Development Labs (USDL), a merger of the Computer Research Group (CRG), UNIX System Group (USG) and the PWB group.
UNIX System V Release 1 was based on System III and the Bell Labs internal UNIX/TS 5.0. System V Release 1 was first released in 1983.