Hi Rod, I think you have mixed up two different systems. The Ferranti Atlas (later ICT/ICL Atlas) was in a custom built building, I understand the CPU occupied two floors, and yes there was one at Harwell I've been told. I would expect that Harwell also had at least one ICT/ICL 1900, and that would indeed run the George 3 multi access system. I did my computer science degree at Queen Mary College (University of London) and we had a ICL 1905E, upgraded to a 1904S which ran George 2 batch processing and the Maximop multi access system. Later I used a 1906 (S?) at the Royal Aircraft Establishment and it used either George 3 or George 4, and I was relieved to find that all the Maximop commands worked on it. When I was in the sixth form we visited the computer centre at the NatWest tower - huge floors - IIRC, one floor had nothing but IBM CPUs (probably 370s - this was 1969) and other static electronics, one floor had all the storage - magnetic tapes, discs, and juke box like machines which picked up strips of magnetic tape. Another floor had the hard peripherals - card readers, line printers and a massive document reader with a curved 'retina' on top about 20 feet across where all the optical sensors were. Another floor had all the cheque reading machines, the operators were moaning about people stapling their cheques and the staples getting caught in the works. At that time a random 2% of the cheques were also processed manually for quality assurance purposes, and presumably to prevent fraud. That day was the first I heard of the fraction of a penny (or cent) scam, where all interest payments were rounded down and all the fractions of a penny credited to the programmer's account. The same day I visited the University of London's central computer centre (as opposed to the individual college's private ones). They had a CDC 7600 and one operator was using a terminal to send messages to chat up a girl operating one of the remote stations which fed the 7600 with punched card data and printed the results. A very early form of Internet chat room you might say. Roger Owner of a ICT 1301 built 1962