Initially, the operating system from the GEC 4000 series was implemented (under pressure from the marketing department, concerned about compatibility with its existing user base) but subsequently a version of UNIX System V Release 2 was added - largely to compete with VAX machines which were becoming the fashionable computer of choice amongst academics, concerned about being able to access software from US colleagues. This was the first port of UNIX to a different processor order code undertaken in the UK. The C compiler, necessary to effect the implementation, was first produced for OS4000 and cross compiled.
The Series 63 was used by several UK universities. One of the first student-run university computing facilities in the UK, Tardis, was established in 1987 in the Department of Computer Science of the University of Edinburgh using a Series 63. The name came from the resemblance of the Series 63's large blue cabinet to Doctor Who's time machine.
The Series 63 was discontinued in August 1987 after disappointing sales.