In 1980, the decision was made to close the DEC10 KI at UMIST as it was getting too expensive to run. It was replaced by a PRIME 750. There was a strong ICF team at UMIST under Bill Swindells and they initially helped with PRIME user support.
By 1982, user support for all Prime users had moved to UMIST, while system support was provided jointly by RAL and UMIST. The UMIST team developed software to distribute and update the software on the remote Primes and a file archiving system whose functionality exceeded anything Prime themselves produced. They also developed an email package, initially providing a similar user interface to that on the GEC systems.
In 1983, PRIMOS Revision 19.1 was released. From then on there were point releases every 15 months or so. The UMIST systems team had to extensively modify each release of PRIMOS to add the extensions that had accumulated over the years.