The Rosenbrock Report had raised the issue of upgrading existing university mini-computers to multi-user capacity, envisaging that up to 5 machines should become part of the Interactive Computing Facility (ICF). In all, 7 machines were eventually approved for upgrades between March 1977 and October 1978. These were located at:
| University Location |
Original System |
Upgraded System |
Potential User Population |
|---|---|---|---|
| Sheffield | Interdata 80 | Interdata 8/32 | 100 |
| Leeds | PDP11/45 | PDP11/70 | 80 |
| Southampton | PDP11/45 | PDP11/45 | 60 |
| Nottingham | Prime 300 | Prime 400 | 60 |
| Swansea | PDP11/40 | PDP11/40 | 50 |
| Oxford | PDP11/45 | PDP11/45 | 50 |
| Manchester Graphics Unit | PDP11/45 | PDP11/45 | 30 |
Apart from Leeds, the ICF provided the capital for the upgrades to each machine, additional terminals and contributed to the recurrent costs of running the machine. In the case of Leeds, the University Grants Committee provided the capital on the understanding that the ICF would provide the recurrent support.
Each of these upgraded facilities provided a valuable additional resource for the ICF and the grant community. They also gave some input into the assessment of systems that might be purchased as part of the new multi-user mini systems programme.
DEC had quite a presence in the small machine market and it was clear that a PDP11 would be a contender. Of the machines upgraded, the largest was the Interdata which gave impressive single user performance albeit rather expensive. The surprise was probably the Prime 300 at Nottingham which performed surprisingly well as a multi-user system. Prime did not have a great deal of penetration in the UK market and what it had was in the engineering area.
Of interest was that Unix had been made available by Bell Labs as an unsupported interactive system on both the Interdata 8/32 and the PDP11 range. However, none of the university engineering machines were running it.
The PDP11/45 had been launched in 1971 and was a 16-bit machine with the possibility of 128K words of memory. The PDP11/70 was introduced in 1975 and was the top-end of the range in 1976. DEC continued to make PDP11s right up until 1990.
Bill Poduska and 6 others started up Prime in 1972 so, in 1976, it was a relatively new company. Bill Poduska had worked on the MULTICS Operating System at MIT. The Prime hardware was based on the Honeywell DDP516 but was 32-bit rather than 16-bit. The PRIMOS operating system was based on MULTICS and written in FORTRAN. The Prime 300 came out in 1973 and was advertised as a 32-bit virtual computer system with each of 31 users (some system ones) being able to compile and run FORTRAN programs independently. Of the machines upgraded, it was the one clearly aimed at the multi-user FORTRAN market. DEC did not really enter the 32-bit market until the VAX arrived in 1978.
