The massification of retail finance in the 1980s relied on the successful deployment of automated teller machines (ATM) and on-line real-time (OLRT) computing during the 1960s and 1970s. We document how the deployment of ATM networks interweaved with the adoption of OLRT computing in Sweden and the UK (alongside a running comparison of similar developments in the USA). Low transaction volume and small retail bank networks facilitated the early adoption of OLRT by savings banks in America. Although they started their computerisation rather ‘late’, British savings banks benefited from adopting ‘tried and tested’ technology while overtaking clearing banks. Meanwhile, Swedish savings banks spearheaded technological change in Europe. In documenting cases of organizational change in Sweden and the UK, we depart from predominant view that considers the development of OLRT in a single move. We put forward the idea that there are specific conditions inside banking organisations that require considering on-line (OL) and on-line real-time (OLRT) as two distinct stage of development in adoption of computer technology. As a result, we show how in the process of diffusion of OLRT computing enabled the transformation of cash dispensers into ATM at the same time that European financial intermediaries were active in shaping technological change.