Manuals as Forensic Evidence: Reconstructing Digital Systems and Administrative Practice

This presentation examines manuals as forensic evidence for reconstructing historical digital systems and the administrative practices that surrounded them. Taking the Swiss Central Aliens Register (Zentrales Ausländerregister, ZAR) as a case study, it asks how historians can reconstruct the operation of a large administrative information system when the system itself is no longer directly accessible. The ZAR was launched in 1971 on an IBM System/360 mainframe, became one of the largest collections of personal data in the Swiss federal administration, and remained in use until 2008. Reconstructing its history therefore requires attention not only to hardware and software, but also to the clerks, offices, forms, validation routines, codes, responsibilities, and temporal rules through which the system was put into practice. The presentation argues that manuals should be read not merely as descriptive documentation, but as prescriptive and procedural sources. They define correct input, valid administrative procedure, authorized work, error handling, navigation, and maintenance. In this sense, manuals make visible how administrative authority was distributed between clerks, software, local offices, central infrastructure, and technical operators. They also reveal how persons and administrative events were translated into machine-readable records through forms, fields, codes, and validation rules. The source corpus combines ZAR programming documentation, user manuals, system administration manuals, early drafts from the Swiss Federal Archives, workspace photographs, and vendor manuals for related hardware such as IBM and ITT terminal systems. By reading these materials together, the presentation reconstructs several layers of the ZAR as a socio-technical system: the physical workspace of clerks, the workstation interface, connection procedures to the mainframe, data entry practices, validation and error routines, system navigation, and processes of debugging, extension, and repair. More broadly, the presentation proposes a forensic method for the history of computing and digital administration. Manuals, especially when combined with archival traces and visual evidence, can help historians move from abstract descriptions of computer systems to situated reconstructions of everyday administrative practice. They show not only what a system could technically do, but how people were expected to use it, how work was standardized, where uncertainty and errors were anticipated, and how administrative routines were encoded into digital infrastructures.