I figure there was only one computer - the computer. Not like today with a virtual machine on any lever close by to test stuff.
I think this was how things where at the time, also in reality at The Swedish Social Insurance Agency and their Bull Cobol machines - you coded in prod and just solved the thing where it was needed.
I recall this from a tour I had some 20 years ago when I was an employee but 20 years is a long time to mess upp memories so I might be wrong.