Milestone-Proposal:The Manchester University 'Baby' computer; Small-Scale Experimental Machine (SSEM)

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Docket #:2020-09

This Proposal has been approved, and is now a Milestone

To the proposer’s knowledge, is this achievement subject to litigation? No

Is the achievement you are proposing more than 25 years old? Yes

Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy. Yes

Did the achievement provide a meaningful benefit for humanity? Yes

Was it of at least regional importance? Yes

Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? Yes

Has an IEEE Organizational Unit agreed to arrange the dedication ceremony? Yes

Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? Yes

Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes

Year or range of years in which the achievement occurred:

1948 - 1951

Title of the proposed milestone:

The world’s first electronic stored program digital computer, 1948.

Plaque citation summarizing the achievement and its significance:

At this site on 21 June 1948 the world’s first electronic stored program digital computer successfully ran a program. Designed and built at the University of Manchester by F.C. Williams and T. Kilburn, it incorporated a successful random-access memory and subsequently contained the first index registers. Based on this design, the world's first commercially produced computer, the Ferranti Mark I, was delivered to the University on 12 February 1951.

In what IEEE section(s) does it reside?

UK & Ireland Section, Region 8

IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:

IEEE Organizational Unit(s) paying for milestone plaque(s):

Unit: UK & Ireland Section, Region 8
Senior Officer Name: Professor Rod Muttram FREng, SMIEEE

IEEE Organizational Unit(s) arranging the dedication ceremony:

Unit: UK & Ireland Section, Region 8
Senior Officer Name: Professor Rod Muttram FREng, SMIEEE

IEEE section(s) monitoring the plaque(s):

IEEE Section: UK & Ireland Section, Region 8
IEEE Section Chair name: Mona Ghassemian

Milestone proposer(s):

Proposer name: Professor Roderick I Muttram CEng, FREng, FIET, FIRSE, SMIEEE
Proposer email: Proposer's email masked to public

Proposer name: Roland Ibbett FRSE, FBCS, CEng, SMIEEE
Proposer email: Proposer's email masked to public

Proposer name: Professor Simon Lavington, CEng, FIET, FBCS,
Proposer email: Proposer's email masked to public

Proposer name: James Miles
Proposer email: Proposer's email masked to public

Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.

Street address(es) and GPS coordinates of the intended milestone plaque site(s):

Bridgeford Street, Manchester M13 9PL. 53 .466218 -2.

Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.

Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need. The plaque will be mounted on the outside of the Coupland 1 Building, Bridgeford Street, in a place where the plaque will be viewable by the public.

Are the original buildings extant?

Yes. The implementation of the computer and its historic first demonstration took place in the Coupland I Building., where the plaque will be located.

Details of the plaque mounting:

The University of Manchester’s provisional plan for the precise location is that the IEEE plaque would replace the existing informational plaque shown in Fig. 1 of the accompanying collection of images

How is the site protected/secured, and in what ways is it accessible to the public?

The public will be able to view the plaque at all hours. Bridgeford Street is pedestrianised and at night this area of the University of Manchester is regularly patrolled by security staff.

Who is the present owner of the site(s)?

The University of Manchester

What is the historical significance of the work (its technological, scientific, or social importance)?

On the morning of 21st June 1948 the Small-Scale Experimental Machine (SSEM), also called the Baby, was the first electronic stored program digital computer to run a program [ref. 1a, 1b]. Fig. 2 in the accompanying collection of images gives an impression of the moment when a factoring program completed its first successful run of about 52 minutes’ duration, having executed some 3.5 million operations.

Looking back, one could say that the 21st June 1948 marked the start of software development and the birth of the Computer Age. When the SSEM first worked, however, it was noticed by contemporary computing pioneers more for its memory system than for its first program – which was small, only 25 instructions [ref. 1c]. The SSEM’s memory system was important because at that time “The most difficult problem in the construction of large-scale digital computers continues to be the question of how to build a memory” [ref. 2].

Memory Development

In the post-war years several potential memory technologies were being suggested, such as: thermionic valves, electro-mechanical relays, magnetic drums, tape or wire; mercury or magneto-strictive delay lines; charge-storage devices. The important design parameters for a computer’s primary memory included: capacity, access-time, cost per bit, reliability. At Manchester, F C Williams and T Kilburn led the way and successfully patented their memory-related inventions [Ref. 3(a)]. So important was the SSEM’s memory technology that it was soon adopted by other pioneering computer design groups, particularly John von Neumann’s group at Princeton and IBM for the 701 and 702 production computers.

The SSEM’s memory system, called Williams-Kilburn Tubes, was based on electrostatic charge-storage and was random-access [ref. 3a, 3b, 3c]. See also Fig. 4 in the accompanying collection of images. In Williams-Kilburn Tubes, selection of a digit was achieved by deflecting an electron beam. Since selection-time was independent of physical location, Williams-Kilburn Tubes offered the first practical implementation of RAM (random-access memory). Most other contemporary memory devices under consideration were of the delay-line type, whose access was sequential (not random). The first computer to become operational using mercury delay line storage was the Cambridge University EDSAC, in May 1949.

The SSEM’s Williams-Kilburn Tubes were the first random-access memory system to have become operational. Other pioneering design teams such as that of John von Neumann at Princeton were hoping to use a random-access memory device called the Selectron [ref. 4], once it had been perfected by RCA. In the event the Selectron was never made available so Princeton adopted Williams-Kilburn Tubes. IBM followed suit, licensing Williams-Kilburn Tubes for their 701 computers. The Whirlwind project at MIT developed a special holding beam storage tube, which was random-access but considerably more complex than Williams-Kilburn tubes. Whirlwind first did useful work in March 1951. The Princeton computer first did useful work in the summer of 1951.

The cost per bit of Williams-Kilburn Tubes made them an economically attractive technology for central registers as well as for primary memory. One Williams-Kilburn Tube could easily store eight 32-bit central registers, at about one fiftieth the cost-per-bit of flip-flop registers. This fact soon led the SSEM team to add a set of general-purpose index (or modifier) registers to their computer – a significant architectural innovation still in use today [ref. 5(a), 5(b)].

Further enhancements

From July 1948 the University team made the following enhancements to the SSEM: increasing the primary memory; extending the word-length from 32 to 40 bits and adding a double-length accumulator; increasing the instruction repertoire to 26 orders, including fast hardware multiply; adding modifier registers; adding a magnetic drum secondary memory with a unique coding system (Phase Encoding, still in use today) [ref. 13]. With the drum secondary memory becoming operational in June 1949, the Manchester computer was probably the first machine to contain the now-familiar combination of two levels of on-line storage: a fast but smaller primary section plus a slower but larger secondary memory.


The strategic importance of the SSEM and its memory system were quickly recognised. In October 1948 Sir Ben Lockspeiser, Chief Scientist at the Ministry of Supply (MOS), paid the SSEM a visit. On 26th October Lockspeiser initiated a UK government contract with the long-established electrical company Ferranti Ltd. to produce a fully-engineered production version of the SSEM [ref. 6]. The resulting production computer was named the Ferranti Mark I. See Fig. 5 in the accompanying collection of images.

In total, the company produced two Ferranti Mark I computers and seven upgraded versions, the Mark I* (pronounced Mark One Star). See also Fig. 6 in the accompanying collection of images. A Ferranti Mark I was installed at the University of Manchester on Monday 12th February 1951 – a world first for the delivery of a commercially-available computer. Constructional details of the Ferranti Mark I are described in [ref. 14a]. The background to the academic/industrial co-operations which led to the Ferranti Mark I are given in [ref. 14b].

By the mid-1950s American companies such as Univac and IBM were installing tens of general-purpose computers in the USA. For various reasons both economic and strategic, it was not until about 1956 that American-produced computers reached non-American destinations. It seems that, in the period 1951 to 1955, Ferranti Ltd. was the only manufacturer willing and able to deliver more widely [ref. 7]. Thus, the first substantial computers to be delivered and put to use in Canada, Holland, Italy and the UK were Ferranti Mark I or Mark I* machines. The first non-British computer to reach the UK was an IBM 650, delivered in October 1956 [ref. 7].

Whilst the hardware and architecture of early Manchester and Ferranti computer designs was innovative and patented [ref. 3a], the software was initially far from user-friendly. Steps were soon taken to improve this [ref. 8a]. By 1954 an Autocode had been developed and “the Mark I became possibly the easiest machine to program in Britain” [ref. 8b]. The Mark I Autocode, probably the first high-level language, was released to users in March 1954; this was a year or two ahead of the US Fortran developments.

What obstacles (technical, political, geographic) needed to be overcome?

The development path which led to the SSEM at Manchester University was not smooth. The storage research was begun by F C Williams in August 1946 in the government’s prestigious Telecommunications Research Establishment (TRE). TRE had several other higher-priority projects in development at the time, such as guided weapons systems. In December 1946 Williams’ storage project transferred to the University of Manchester’s Department of Electro-technics when Williams was appointed Professor. He inherited a Department in the doldrums after staff resignations [ref. 10]. In particular it lacked any existing electronics staff or electronics equipment. So Williams was fortunate to get agreement to import all his research resources from TRE, free of charge to the University. Freddie Williams’ close TRE colleague Tom Kilburn was seconded to Manchester and registered for a Ph.D. The TRE engineer Arthur Marsh was also transferred but quickly decided that ‘there was no future in digital computers’ [ref. 1(c)]. Fortunately TRE seconded a replacement engineer, Geoff Tootill, who was enthusiastic. The SSEM was developed by Williams, Kilburn and Tootill, using TRE resources.

There is, of course, more to a computer than its memory system and central processor hardware. In 1949 Williams said: “When I first entered the field of computers, fresh from the field of radar after the war, I was prepared to believe you could do a lot with electronics because I had had some experience of it, but the stumbling block, the thing I didn’t see, was how the programme was organised to be put onto these [computing] machines with a finite amount of effort and of space in the machine”. [ref. 11]. Help was needed from the mathematicians.

Fortunately Manchester’s Mathematics Professor Max Newman, who had supported F C Williams’ appointment, was interested in the possible uses of general-purpose computers. In May 1946 Newman had obtained a Royal Society grant of £35,000 to set up a Computing Machine Laboratory to investigate mathematical applications. Newman and one of his mathematics lecturers, I J Good, had spent a week visiting Alan Turing at the National Physical Laboratory to gain ideas. Then Newman had spent three months in the autumn of 1946 visiting John von Neumann’s computer design group at the Institute for Advanced Study, Princeton. It seems that Max Newman and Jack Good hoped to acquire a computing machine of a similar nature to von Neumann’s using Selectron storage tubes [ref. 12], but this never happened.

Unfortunately Jack Good left Manchester in April 1948 but the outstanding mathematician Alan Turing joined Newman in October 1948. Turing’s salary was the first call upon the Royal Society grant. Thus, Newman and Turing were fortunately in place in 1949 to advise Williams and Kilburn on system software for the enhanced Manchester computer. See Fig. 3 in the accompanying collection of images. Newman and Turing also specified the first useful program (investigation of Mersenne Primes) in April 1949. Finally, Newman agreed to spend £20,000 of his grant on the provision of a new, custom-designed, Computing Machine Laboratory which was required to house the Ferranti Mark I computer when it was delivered in February 1951.

What features set this work apart from similar achievements?

Manchester University’s early computer design efforts were characterised by the production of useful results by a small academic team, leading to fruitful co-operation with local industry. From January 1947 to September 1948 the hardware team essentially consisted of just three people: F C Williams, T Kilburn and G C Tootill. In September 1948 they were joined by three hardware research students.

The hardware designs were passed to Ferranti Ltd. in the period between December 1948 and November 1949, with appropriate exchange of personnel between academia and industry. About 35 patents were filed by F C Williams and colleagues at Manchester University between November 1947 and March 1950 [ref. 3(a)]. This was almost three times the total number of patents filed by all the other UK computer design groups over the same period.

On the software side, Alan Turing came to Manchester University in October 1948. Alan Turing was responsible for the input/output routines and other basic library subroutines of the early Manchester computers. An assistant mathematician, Cicely Popplewell, was appointed in October 1949. Then in October 1951 R A (Tony) Brooker arrived to head up the University’s Computing Service. In summary, the software team associated with the early Manchester computers was relatively small.

Alan Turing and Max Newman were the first users of the early Manchester computer. Useful theoretical work was done in the spring of 1949 and in the period October 1949 to August 1950, investigating Mersenne primes and the Riemann hypothesis. A more practical application involved optical ray tracing for high-precision lens design. There was then a pause whilst a new building, the Computing Machine Laboratory, was completed to house the production computer. The Ferranti Mark I arrived in February 1951. Alan Turing issued the 100-page Users’ Programming Manual in March 1951.

From its very small beginnings in 1948, use of the computing facilities at Manchester University grew rapidly after the installation of the Ferranti Mark I. During calendar year 1955, 104 people were trained to use the machine and 66 scientific papers were published based on machine results [ref. 1c]. The community of users at Manchester had grown to include 15 University departments, three industrial research associations, seven engineering companies and nine government establishments [ref. 1c]. By 1955 a total of seven Ferranti-manufactured derivatives of the SSEM had been installed at customer’s sites and a further two computers would be installed by the end of 1957. The nine sites together covered four countries: UK, Canada, Holland and Italy [ref. 7]. The influence of the 1948 SSEM (the Baby) therefore grew, making a significant presence on the world stage.

Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English, or accompanied by an English translation.

. (a). F C Williams & T Kilburn, Electronic digital computers. Letter to Nature, vol. 162, September 1948, page 487. This Letter includes the following text: “A small electronic digital computing machine has been operating successfully for some weeks in the Royal Society Computing Machine Laboratory, which is at present housed in the Electrical Engineering Department of the University of Manchester. The machine is purely experimental, and is on too small a scale to be of mathematical value. It was built primarily to test the soundness of the storage principle employed and to permit experience to be gained with this type of machine before embarking on the design of a full-size machine. However, apart from its small size, the machine is, in principle, 'universal' in the sense that it can be used to solve any problem that can be reduced to a programme of elementary instructions; the programme can be changed without any mechanical or electro-mechanical circuit changes. … It will, of course, be understood that it is intended to have other arithmetical facilities, as well as a much larger store, in a full-sized machine … At present routines are chosen with the sole object of testing the machine as thoroughly as possible. The development of this machine has been very actively supported by the Telecommunications Research Establishment, Great Malvern”. See also Fig. 2 in the accompanying collection of images.

1 (b). M H A Newman, Status Report on the Royal Society Computing Machine Laboratory, prepared for an internal committee of the Senate of the University of Manchester, 15th October 1948. Max Newman, Professor and Head of Mathematics at Manchester University, had obtained a grant from the Royal Society in May 1946 to establish a Computing Machine Laboratory. In his October 1948 Report Newman explains the difficulties in acquiring a digital computing machine for his proposed Laboratory. He highlights the engineering problems in finding “a satisfactory memory unit or method of storage of information” and the delays in obtaining Selectron memory units from RCA. Newman goes on to state that “a small prototype of the [digital computing] machine using Professor Williams’ storage came into action about three months ago in the Electrical Engineering Laboratory and is thus the first of these automatic general-purpose computing machines to have actually worked”. The mathematician Max Newman had led the Colossus cryptanalytical group at Bletchley Park during the war. Newman kept in touch with John von Neumann at the Institute of Advanced Study at Princeton and had visited their computer design group at Princeton from October to December 1946. Newman had organised a Discussion on Computing Machines at the Royal Society, London, on 4th March 1948 at which there were short presentations from most of the UK’s embryo computer design projects. Max Newman would therefore have been aware of any stored-program machine that might have pre-dated the SSEM. It is believed that the main challenger was the EDSAC computer at the University of Cambridge, which first ran a program on 6th May 1949.

1 (c). The first program is reproduced in: S H Lavington, A History of Manchester Computers, Second edition, published in 1998 by the British Computer Society. ISBN 0-902505-01-8.

2. Nathaniel Rochester (IBM), Radio progress during 1949: electronic computers. Keynote paper in the Proceedings of the IRE, April 1950, page 374.

3 (a). The Williams Tube (or more strictly the Williams-Kilburn Tube) stored digital information as a matrix of electrostatically-charged areas on the phosphor coating of a cathode ray tube. See Fig. 4 in the accompanying collection of images. The unique feature of the Williams Tube was its method of automatically refreshing the charge pattern before it decayed. The economic benefit of the system was its low cost per bit: it could be built from standard CRTs. The first patent for Williams Tube memory was UK Application Number GB19460036587, with the title of Apparatus for storing trains of pulses. This was filed on 11th December 1946 in the name of F C Williams who was at the time employed by the government’s Telecommunications Research Establishment. A number of subsequent storage patents followed, mostly in the joint names of F C Williams and T Kilburn. The list of all patents emanating from F C Williams’ Manchester University computer design team in the period January 1947 to 1st March 1950 is given below, based on an analysis of all patents from January 1943 to October 1991 inherited by or administered by NRDC. (This analysis was compiled in 2018 by Roger Cullis, a former NRDC senior patent attorney, using data from the European Patent Office World Patents Index). The time-period of the following Manchester University patents embraces all the novel technical developments associated with the SSEM and its subsequent enhancements. Date Title of patent Name(s) of inventors 20/10/47 Electrical information storage apparatus FCW, TK 22/05/48 Information storage means FCW, TK 26/07/48 Improvements in or relating to electronic ccts for digital comp. systems FCW, TK 26/07/48 Electronic circuit for adding binary numbers FCW, TK 13/10/48 Electronic digital computing apparatus FCW, TK 01/11/48 Electrical information storage apparatus FCW, TK 23/12/48 Pulse selecting circuits FCW, AAR, TK 23/12/48 Circuit for adding binary numbers FCW, AAR, TK 23/12/48 Circuit for multiplying binary numbers AAR 23/12/48 Pulse selecting circuits FCW, AAR, TK 31/01/49 Electronic digital computing device FCW, TK 1/03/49 Magnetic storage systems for electronic binary digital computers FCW, JCW 1/03/49 Magnetic storage systems FCW 14/03/49 Improvements in or relating to electronic ccts for multiplying binary nos FCW, AAR 14/03/49 Electronic circuit for multiplying binary numbers FCW, AAR 3/06/49 Electronic digital computing devices [This patent refers to B-lines, later known as Index registers] FCW, TK, GCT, AAR, MHAN 7/06/49 Electrical information storage means FCW, TK, GCT 7/06/49 Improvements in or relating to electronic digital computors FCW, TK, GCT 7/06/49 Electronic digital computers FCW, TK 22/06/49 Electronic digital computing machines FCW, AAR 22/06/49 Electronic digital computing machines FCW, TK, GCT, GET, DBGE 22/06/49 Electronic computing devices with subsidiary storage FCW, TK, GET, DBGE, GCT 22/06/49 Improvements in or relating to digital computors FCW, TK, GET, DBGE, GCT 22/06/49 Improvements in or relating to electronic digital computing machines FCW, TK, GET, DBGE, GCT 22/06/49 Electronic digital computing machines AAR, FCW, TK 8/08/49 Electrical signal detecting and amplifying systems FCW, TK 17/08/49 Electronic digital computing machines FCW, TK 17/08/49 Electronic digital computing machines FCW, TK, GCT 14/11/49 Electronic storage devices FCW, TK 14/11/49 Electronic information storage devices FCW, TK, GCT 16/11/49 Digital computing machine FCW, TK, GET 16/11/49 Improv in magnetic rec or reproducing devices partic for dig comp mcs FCW, TK, GET 22/11/49 Electronic information-storing devices FCW, TK 1/12/49 Electrical storage apparatus FCW, TK, GCT 19/01/50 Electronic information storage device FCW 16/02/50 Improvements in or relating to electronic information-storing devices FCW 1/03/50 Magnetic storage system for electronic binary digital computers FCW, JCW

The identification and bio notes for the inventors in the above Table are: Initials Name Relevant dates at Manchester University, status during period ending March ‘50, etc. DBGE Dai Edwards Sept. ’48 onwards; EE research student TK Tom Kilburn Dec. ’46 onwards; TRE employee, then EE lecturer MHAN Max Newman Oct. ’45 onwards; Professor of Maths AAR Alec Robinson April ’47 – April ’49; EE research student, then to Ferranti GET Tommy Thomas Sept. ’48 – Sept. ’55; EE research student GCT Geoff Tootill Sept. ’47 – Nov. 49; TRE employee, then to Ferranti JCW Cliff West Oct. ’46 – Dec. ’57; EE research student, then assistant lecturer FCW FC (or Freddie) Williams Dec. ’46 onwards; Professor of EE

The first widely-circulated report describing the Williams/Kilburn storage technology was: 3 (b). T Kilburn, A storage system for use with binary digital computing machines. Typed foolscap report dated 1st December 1947, consisting of 52 pages of text, 32 pages of diagrams and one page with three photos. This report was produced for the Telecommunications Research Establishment (TRE). At the time Kilburn was on secondment from TRE, working with Professor F C Williams in the Electro-technics Department at Manchester University. It is known that several copies of this Report were taken to the USA in the spring of 1948 by Douglas Hartree (Cambridge University), Harold Huskey (SWAC at UCLA) and A M Uttley (TRE).

The first paper to appear in a scientific journal was: 3 (c). F C Williams & T Kilburn, A storage system for use with binary digital computing machines. Proc. IEE, Vol. 96, part 2, No. 30, 1949, pages 183 ff.

4. Jan Rajchman, The Selective Electrostatic Storage Tube. RCA Review, Volume 12, No. 1, pp 53 - 97, March 1951.

5 (a). The idea of index registers, initially called B lines on the Manchester University computer, arose between 15th July and 13th October 1948. Evidence comes from G C Tootill’s laboratory notebook, which is preserved as item NAHC/MUC/2/C3 in the National Archive for the History of Computing in Manchester. Working B line hardware was in use on the computer by April 1949. The relevant UK Patent was filed on 3rd June 1949 – see list in ref. 3(a) above.

5 (b). The first paper to appear in a scientific journal that mentions the modifier registers is: T Kilburn, The University of Manchester universal high speed digital computing machine. Nature, Vol. 164, Oct. 1949, pages 684 – 691.

6. The full text of the 26th October 1948 letter sent by Sir Ben Lockspeiser to Eric Grundy, Manager of Ferranti’s Instrument Department at Moston, Manchester, reads as follows: Dear Mr Grundy, I saw Mr Barton [MOS] yesterday morning and told him of the arrangements I made with you at Manchester University. I have instructed him to get in touch with your firm and draft and issue a suitable contract to cover these arrangements. You may take this letter as authority to proceed on the lines we discussed, namely, to construct an electronic calculating machine to the instructions of Professor F C Williams. I am glad we were able to meet with Professor Williams as I believe that the making of electronic calculating machines will become a matter of great value and importance. Please let me know if you meet with any difficulties”.

7. S H Lavington, Early computing in Britain: Ferranti Ltd. and government funding, 1948 – 1958. Published by Springer, 2019. ISBN: 978-3-030-15102-7.

8. R A (Tony) Brooker, who took over from Alan Turing in October 1951 as leader of the systems software support for the Ferranti Mark I, developed a high-level language (an Autocode) for the computer:

8 (a). R A Brooker, An attempt to simplify coding for the Manchester computer. British Journal of Applied Physics, Vol. 6, September 1955, pages 307 – 311.

8 (b). M Campbell-Kelly, Programming the Mark I: early programming activity at the University of Manchester. Annals of the History of Computing, Vol. 2 no. 2 April 1980, pages 130 – 168.

The Mark I Autocode avoided three difficulties facing all early programmers: (i) the awkward machine code in which programs had to be written, making software difficult to update and adapt; (ii) the necessity for the user to frequently swap information between the fast (but small) primary memory and the slow (but large) secondary memory during run time; (iii) scaling and precision: the need to be aware of the limited number-range of fixed-point and to perform most scientific and engineering calculations in floating-point arithmetic, for which there was no hardware support.

The Mark I Autocode is best introduced by a short sequence which prints the root mean square (RMS) of the floating-point variables v1, v2, … v100. n1 = 1 v101 = 0 2v102 = vn1 x vn1 v101 = v101 + v102 n1 = n1 + 1 j2, 100 ≥ n1 v101 = v101/100.0 *v101 = F1(v101)

The 5-track paper tape for this sequence would have been prepared on a special teleprinter in the Computing Machine Laboratory which had been adapted with appropriate printable symbols (illustrated here in the type font Times New Roman). In the Autocode convention, n1 is an integer and v1 etc are floating-point numbers. The symbol * causes the printing of a variable to ten decimal places on a new line and F1 signifies the intrinsic function square root.

The Autocode was released to users in March 1954, a year or two ahead of the American Fortran developments. Autocodes were developed for a range of British computers by Ferranti Ltd., Elliott Automation Ltd. and ICT. By 1961 the world-wide proliferation of high-level languages had led the Manchester team to develop the Compiler Compiler [ref. 9 (a, b, c)], another software landmark.

9 (a). The basis for the Compiler Compiler was first described in: R A Brooker & D Morris, An assembly program for a phrase structure language. Computer Journal, Vol. 3(1960), page 168.

9 (b). A number of UK-based papers followed but the developments did not come to universal attention until this publication: S Rosen, A Compiler-Building System Developed by Brooker and Morris. Comm. A.C.M., Vol. 7, No. 7, July 1964, pages 403 - 414.

9 (c). The history of the Compiler Compiler development, including a retrospective Appendix by Tony Brooker, is presented here: S H Lavington and others: Tony Brooker and the Atlas Compiler Compiler. February 2014 & revised April 2016:

10. The outgoing Professor Willis Jackson and his research group quit the Department of Electro-Technics in September 1946. This left the Electro-Technics Department severely depleted and especially so in the area of electronics. Albert Cooper, the Department’s Chief Technician, was reported to be “disgusted” with Jackson’s move because it seemed to him that “the whole of the Department was disappearing into Jackson’s van”. The full history is recounted in: Electrical Engineering at Manchester University; the story of 125 years of achievement. T E Broadbent. Published by The Manchester School of Engineering, University of Manchester, 1998. ISBN 0 – 9531203 – 0 – 9.

11. On 19th and 22nd August 1949 F C Williams gave two lectures in Canada at the National Research Council’s Atomic Energy project, Research Division, Chalk River, Ontario. These lectures were typed up from a wire recording and bound as Report LT-24, 14th Sept. 1949, High speed universal digital computers. (28 typed pages and 16 figures). This Report essentially describes the Williams CRT storage system, the SSEM computer and the June 1948 factoring program. Report LT-24 is preserved as item NAHC/MUC/1/D5 at the National Archive for the History of Computing in Manchester.

12. It is clear that Max Newman intended to acquire a computer rather than designing and building one himself. Surviving records are sparse but Jack Good kept notes from which it seems that the Manchester mathematicians favoured a machine based on von Neumann’s IAS project at Princeton rather than on Alan Turing’s ACE project at NPL. In the event, a Pilot version of the ACE computer did not run a program at NPL until May 1950 and the IAS computer did not work at Princeton until early 1951. Good’s notes are available as follows: Early Notes on Electronic Computers. I J Good. 78 typed and hand-written pages mostly covering the period 1947-8, with Good’s retrospective introduction dated 23rd March 1972, and Good’s covering letter to Simon Lavington dated 7th April 1976. Catalogue NAHC/MUC/2/A4 in the National Archive for the History of Computing. An analysis of Good’s notes is given in reference 7 above.

13. F C Williams & T Kilburn, The University of Manchester computing machine. Inaugural conference of the Manchester University computer, July 1951, pages 5 – 11. This paper was also presented at the Joint AIEE/IRE Computer Conference, Philadelphia, December 1951. This illustrated paper describes the progression from the 1948 SSEM (Baby) computer, via 1949 enhancements, to the final commercial version known as the Ferranti Mark I. A pdf of this paper is attached.

14 (a). B W Pollard & K Lonsdale, The construction and operation of the Manchester University computer. Proc IEE, Vol. 100, part 2, 1953, pages 501 – 512. A pdf of this paper is attached. See also Fig. 5 in the accompanying collection of images.

14 (b). T Kilburn, G C Tootill, D B G Edwards & B W Pollard, Digital computers at Manchester University. Proc. IEE, Vol. 100, part 2, 1953, pages 487 – 500.

Supporting materials: 1. Pdf of a letter dated 29th September 2020 from the University of Manchester regarding the installation of an IEEE Milestone plaque. Media:Baby_Plaque_UoM_letter.pdf 2. Word document containing seven photographs plus explanations. Media:BabyPhotosV2.doc 3. Pdf of reference [13], the paper presented by F C Williams and T Kilburn at the July 1951 Inaugural Conference of the Ferranti Mark I computer. Media:Inaug Conf Ref 13.pdf 4. Pdf of reference 14(a), the Proc. IEE paper by Pollard and Lonsdale. Media:IEE_Pollard_Lonsdale_19530146.pdf

Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to Please see the Milestone Program Guidelines for more information.

Please email a jpeg or PDF a letter in English, or with English translation, from the site owner(s) giving permission to place IEEE milestone plaque on the property, and a letter (or forwarded email) from the appropriate Section Chair supporting the Milestone application to with the subject line "Attention: Milestone Administrator." Note that there are multiple texts of the letter depending on whether an IEEE organizational unit other than the section will be paying for the plaque(s).