Making IT Work – Abstracts of Papers

Monday 22^nd May 2017

Large reconstruction and restoration projects invariably involve high levels of motivation and commitment. None is without heroic tales of setbacks, ingenuity, obstinacy, determination, expertise and sacrifice over sustained periods of time. We applaud, and so we should. But how do we justify these huge undertakings? To what category of object do these new-old machines belong – fictitious antiques, new primary sources, sculpted monuments? How important is physical fidelity to historical authenticity? What is the social and historical value of such projects to their makers, to the scholarly community, and to visitors who view them? What, if anything, is learned that could not otherwise be learned? And what kind of history is it we do when we undertake these enterprises? This paper uses as case studies major reconstruction and restoration projects from the last three decades to address a raft of questions agitated by such projects – museological, historiographical and social.

The EDSAC Replica Project started in 2011 with the ambition to recreated EDSAC, the world’s first practical stored program electronic digital computer and the construction is now substantially complete. The original EDSAC ran its first programme on 6^th May 1949 and went on to provide a computing service to the University of Cambridge for almost 10 years. The computational advantage it gave to Cambridge research is acknowledged by three Nobel Prize winners from that time.

The EDSAC was unceremoniously scrapped in 1958 to make room for its successor EDSAC 2. Some documentation at the level of architectural and logical design was deposited in the university library but very few mechanical drawings or circuit schematics were found. Some further detail is given in later retrospective papers by the pioneers and in related secondary sources, but for the reconstruction the starting point was photographs of the original. From this baseline a dedicated team of volunteers engaged in the construction of a replica of EDSAC as it was when used as a service machine. In our paper we describe how the detailed design of EDSAC was forensically reconstructed, including the compromises that have been made to meet the available budget, satisfy modern safety standards and provide a working exhibit for The National Museum of Computing. We describe the challenges faced in running a large scale reconstruction project and the lessons we have learned. We also comment on the knowledge recovered of how the pioneers of the 1940s designed digital systems in what was essentially an analogue age

The author’s experience with the restoration of the Pegasus and the Elliott 401 computers, together with the project to replicate the Manchester Baby computer, is drawn on to review various issues associated with maintaining such systems in working order. Some consequential thoughts on sustainability, i.e. for how long will the objects be seen to be useful, will follow. The indispensable value of appropriate volunteers will be highlighted. The discussions are based on the premise that an operational artefact is vastly more useful than a static one.

After reviewing the evolution of the traditional museum and its practices, we examine the emergence of the dissenting world of Operational Preservation and the suspicion with which this is regarded.

But in the fields of Transport and Industrial Preservation a great body of praxis has already built up, and the principles of curatorial ethics we require are well established in historic-building conservation and elsewhere.

If we regard the experience of an environment or process in action as the ‘object’ being conserved, and the skills so required as another, we can propose a typology of both material and non-material artefacts, with their parallel codes of ethics and curatorship, and find a foundation for more systematic judgements about the classic conflicts of intent.

The Computer History Museum in Mountain View, California, sponsored long-term projects beginning in 2003 to fully restore and exhibit two IBM 1401 systems and a DEC PDP-1. A volunteer team of retired IBM customer engineers together with Silicon Valley engineers contributed over 30,000 hours over five years to restore the two 1401 mainframes plus some unit record equipment. The 1401 team also designed a 729 magnetic tape drive emulator to debug the tape control circuits while the PDP-1 team built hand controllers for the vintage Spacewar! video game. In 2013, the museum remodeled the raised-floor labs to accommodate live public demonstrations and interpretive media. In the 1401 Demo Lab, accredited docents invite visitors to keypunch their names into punched cards which they then see printed by the cacophonous 1403 chain printer. In the PDP-1 Demo Lab, visitors pit duelling Spacewar! spaceships against each other on a large cathode ray tube display. This paper covers the project organization, culture, and teamwork that led to these two successful vintage computer restorations and authentic “time machine” visitor experiences.

A multi-generational volunteer team at the Vintage IBM Computing Center at TechWorks! in Binghamton, New York, has revitalized a 1960s IBM 1403-N1 high-speed printer, designed and built for IBM’s System/360. Using a three-pronged approach, this two-plus year effort combined conservation of the printer’s mechanical components, reverse engineering of controller hardware in today’s technology, and implementation of real-time software to perform complex functions originally controlled by hardware. The IBM1403-N1 printer is regularly demonstrated for TechWorks! visitors, for whom personalized souvenir banners are printed on classic 20th century fanfold paper.

The objectives and the complexity of computer conservation projects can vary within a broad range. The Heinz Nixdorf MuseumsForum in Paderborn, Germany, follows different approaches to address the trade-off between partially opposing restoration goals.

On the one hand a museum’s task is to encourage visitors from all ages and backgrounds to understand and reflect on the evolution of information technology from the very beginning to the digital internet era of today. This requires simplification and an entertaining presentation. On the other hand this simplification must not lead to historic inaccuracy and a precise reconstruction of historic facts and machines is always an important objective. Also, available manpower, knowledge and budget determines the scope of a restoration project.

We present three different projects realized by the museum to show the possible trade-offs between these restoration goals. These include a restoration of a relay based Turing machine, a remake of the first German automatic game machine “Wolf and Sheep,” and the award winning build of an interactive ENIAC accumulator.

Tuesday 23^rd May 2017

Restoration of the ICL 2966 system at The National Museum of Computing has been ongoing since 2009. In this session we will look at some of the problems faced and how they were solved, as well as the remaining challenges. We will also look at the custom hardware interfaces and emulation techniques that helped to bring the system back to life and continue to play a part in making day-to-day operation of a large mainframe system practical in a museum environment.

An ongoing project at The National Museum of Computing is to present to the public an early air traffic control system. This paper discusses the importance of capturing an extensive range of information relating to the system at the point of donation. I describe the value of this information within the restoration process, the techniques used in the restoration itself, and the value of expressing the social impact of the system in order to convey its relevance to the public.

Phil Hayes: “Colossus: The Light is on but the Door is Shut”

We describe the 14 year struggle, with little or no information, to rebuild Colossus IX.

The original mercury delay line store of the EDSAC will be described, and the reasons why it would be difficult to make an exact working replica of it set out. Instead a technology dating from three or four years later, the wire delay line, is used and this design will be explained, as will the determination of the parameters needed for its construction.

As with any non-trivial technology, a full range of tests is needed and the key tests used for setup and acceptance testing of the individual delay units will be described. Finally, the tests used in sub-system integration and for monitoring correct operation in the running machine will be outlined.

The Harwell Dekatron Computer, also known as WITCH, was designed in 1949 to produce mathematical tables for the Atomic Energy Research Establishment at Harwell near Oxford in the UK. After a long working life, including in education, the machine came to The National Museum of Computing in 2009. Key components and systems needed careful repair, but the original conservative design has ensured it can now be regularly demonstrated to the public. Those repairs will be discussed and the machine demonstrated.