Issue Number 78 Summer 2017 Computer Conservation Society Aims and objectives The Computer Conservation Society (CCS) is a co-operative venture between BCS, The Chartered Institute for IT; the Science Museum of London; and the Museum of Science and Industry (MSI) in Manchester. The CCS was constituted in September 1989 as a Specialist Group of the British Computer Society. It is thus covered by the Royal Charter and charitable status of BCS. The aims of the CCS are: To promote the conservation of historic computers and to identify existing computers which may need to be archived in the future, To develop awareness of the importance of historic computers, To develop expertise in the conservation and restoration of historic computers, To represent the interests of Computer Conservation Society members with other bodies, To promote the study of historic computers, their use and the history of the computer industry, To publish information of relevance to these objectives for the information of Computer Conservation Society members and the wider public. Membership is open to anyone interested in computer conservation and the history of computing. The CCS is funded and supported by voluntary subscriptions from members, a grant from BCS, fees from corporate membership, donations and by the free use of the facilities of our founding museums. Some charges may be made for publications and attendance at seminars and conferences. There are a number of active projects on specific computer restorations and early computer technologies and software. Younger people are especially encouraged to take part in order to achieve skills transfer. The CCS also enjoys a close relationship with the National Museum of Computing. Resurrection The Journal of the Computer Conservation Society ISSN 0958-7403 Number 78 Summer 2017 Contents Society Activity 2 News Round-Up 10 Programming the ENIAC and Electronic Analogue Computers 11 Rainer Glaschick Miniature Bricks : CCS Visit to the Deutsches Museum, Munich 14 Ben Trethowan Big Physics and Small Computers 19 Geoff Sharman A Long-Undiscovered Bug 25 David Holdsworth Letter to the Editor : Teleprocessing and LEO? 25 Frank Land Obituary : Harry Huskey 30 Martin Campbell-Kelly John Poulter Papers 31 Martin Campbell-Kelly 50 Years Ago …. From the Pages of Computer Weekly 32 Brian Aldous Forthcoming Events 35 Society Activity Software — David Holdsworth Kidsgrove Algol There have been various improvements to David Huxtable’s brick 20 (the most indispensable missing component), and we can now compile quite a variety of ALGOL 60 programs. Not only that, we can also run them, using our rather rudimentary run-time system and library of standard functions. A significant part of our development has relied on reverse engineering other missing material, especially the POST system’s PANACEA module which provides the API to magnetic tape and which is essential for the Kidsgrove compiler. This development has involved putting specific facilities into my own emulator. This means that the compiler will not run on any other emulator. I have constructed equivalent facilities using KDF9 code, and we now have a version that will generate KDF9 Usercode and will run on any KDF9 emulator — or even a real KDF9. The plan is to use Bill Findlay’s emulator ee9, which we also use for our Whetstone Algol facility (kdf9.settle.dtdns.net) At present our code is proving to be quite a good test program for ee9. We do not have brick 84, the Usercode compiler for use with POST. Hitherto we have used my own assembler for converting the compiler output to KDF9 binary code. A few months ago. Brian Wichmann discovered a listing of the Paper Tape Usercode Compiler in the Science Museum archives, and now we have this operational. It always had a flaky reputation (deserved). It remains to produce a better engineered integration of this last phase of the compilation, and further experiments are necessary to determine the best way to do this. A further area of imperfection is our somewhat Heath- Robinson means for incorporating the library routines and the run-time system. Brian Wichmann still has his ALGOL 60 test suite, and he is keen to try it with our resurrected Kidsgrove Compiler. There is a little demonstration at: kdf9.settle.dtdns.net/KDF9/kalgol/DavidHo/demo.zip. 2 Resurrection Summer 2017 Analytical Engine — Doron Swade Excellent progress on the database of the Babbage technical archive. Tim Robinson in the US has produced a searchable database of all catalogued material with related content fully cross-referenced. Each item links directly to the corresponding Science Museum catalogue entry and to the recently available (low resolution) online scans of the originals. This work covers all technical drawings and related Notations (there are some 2,200 Notations for the Analytical Engine). A small amount of material that is known to exist but is not yet in the Science Museum catalogue remains yet to be done. Back in London I have completed a Quick Index of the 26 volumes of Babbage’s Scribbling Books — Babbage’s scratchpad daybooks. The Index identifies all material specifically relating to the Mechanical Notation, Babbage’s language of signs and symbols that he used to describe and specify his engines. The Scribbling Books comprise 8,100 folio sides each of which has been examined for relevant content. The Quick Index is a retrieval and navigation tool to support ongoing research into the notational language with a view to further decoding the Analytical Engine designs. It is thought to be only the third time in history that the set of Scribbling Books has been gone through in their entirety. The only known precedents for this are the work of the late Bruce Collier and the late Allan Bromley in the 1960s and 70s. The next step on the main database is to go systematically through the Scribbling Books, extract all cross references, tag subject content and transcribe significant material. This process is expected to be completed by the end of the year. Material already transcribed for the Notation Quick Index will be directly imported. North West Group contact details Chairman Tom Hinchliffe: Tel: 01663 765040. Email: [email protected] Secretary Gordon Adshead: Tel: 01625 549770. Email: [email protected] Resurrection Summer 2017 3 EDSAC Replica — Andrew Herbert The major item to report is the adoption of a new design for flip-flop circuits in certain areas of the machine. These circuits have been problematic since the outset of the project. In the EDSAC Report there is a circuit diagram labelled “Flip-Flop” but it shows no values for the RC components, and finding a set of values that would give the behaviour of the modern understanding of a flip-flop eluded us. Eventually the penny dropped that the circuit is actually a monostable with a set/reset facility — the monostable being tuned in each situation to hold a value for as long as it is required by the logic to which it belongs. This interpretation of the circuit was later confirmed in the cache of EDSAC circuit diagrams donated to us by John Loker, a former Mathematical Laboratory engineer. In most places the monostable design has worked reasonably well. But in Main Control it has been a different story: this unit has to retain the bits of an order throughout its execution — and for I/O, shift and multiply this can be a very long time. Setting component values suitable for this period gives a circuit that is slow to set and reset and thus the flip-flop cannot be clocked at the rate of the fastest instructions, leading to errors. The main control team, James Barr, Tom Toth and Simon Kelley, have wrestled with this problem for almost 12 months and we have finally given up and decided to adopt a bistable circuit more like a modern flip-flop. We know from the Loker drawings that the EDSAC pioneers had moved to a bistable circuit later in the life of the machine, but we had assumed this was much later than our target of the 1949-51 EDSAC. However from some of the documentary sources and closer inspection of the photographs of the original machine we have convinced ourselves that they experienced the same issues as ourselves and put in bistables as early as 1951. The other item of note is that we are now gradually introducing the nickel delay lines made by Peter Linington into the machine, replacing Nigel Bennée’s “Digital Tank Emulators” used up until now to simulate the delay line stores. So far just the Counter register (in the Coincidence Unit) has been connected to its (short) delay line and shown to be satisfactory. The remainder of the short delay lines will be connected as and when the coffin to hold them is ready to do so, and this is imminent. The large coffin was put in place at the back of the machine earlier this week and a start made by Peter Linington and Andrew Herbert installing the internal racking needed to hold the delay lines in their “pizza box” receptacle. Progress has been made in other areas: Martin Evans has a working paper tape reader electronics chassis and all the Storage Regeneration Units (chassis 01) have been updated to the latest revision and thoroughly 4 Resurrection Summer 2017 tested. Most of the coaxial cabling for connecting these units to the delay lines has been put in place. The entire arithmetic unit has been moved from Nigel Bennée’s laboratory in Cambridge to TNMoC and is being recommissioned ready for hooking up to Main Control. Our hope is for a big step forward once the monostables in Main Control are replaced by bistables: we should be able to demonstrate a working order fetch, decode and execute cycle and from that test each of the 18 EDSAC orders in turn.