CERN LIBRARIES, GENEVA CERN/SPC/220 28 February, 1966

CM-P00095068

ORGANISATION EUROPÉENNE POUR LA RECHERCHE NUCLÉAIRE CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH

SCIENTIFIC POLICY COMMITTEE

Thirty-eighth Meeting

8 March, 1966

EXTENSIONS TO THE CERN COMPUTING FACILITIES

by Dr. M.G.N. Hine

The attached paper contains a review of CERN's needs from its central computing facilities, both in the near future and as far as 1969-1970. It describes possible ways in which these needs might be met within the budget forecasts, and suggests an optimum way to proceed.

The scientific policy is to be discussed at the Scientific Policy Committee meeting on 8th March. If the policy line is cleared at that meeting, the Finance Committee could start discussion of the contractual implications at its meeting on 10th March. The Finance Committee would not be pressed to give final decisions at that meeting about contract adjudications, but those decisions will be needed in the near future.

66/348/5 CERN/SPC/220

EXTENSIONS TO THE CERN COMPUTING FACILITIES

1. Introduction

The need to continue the development of computing facilities at CERN in order to keep pace with the rapidly growing use of com• puting and digital techniques in high-energy physics has been ex• plained on several occasions to the Scientific Policy Committee and the Finance Committee, and money has been reserved in the future budget forecasts for this purpose. A review of our needs has been made recently in the light of a year's experience of use of the CDC 6600 and associated equipment, and this paper describes the conclusions and the policy we propose to follow. An internal tech• nical report (DD/CO/66/I) is annexed, giving details of the future needs, the performance of the 6600, the possible ways of development and their financial implications.

2. History

A major study of CERN's computing needs was made in 1963 by the European Committee and its working party, who reported that CERN should provide for a great increase in ordinary computing load over the period 1965-1969, allowing for the use of complicated on-line applications involving large programmes such as HPD and spark chamber experiments, and in addition should develop a system of remote operating consoles, whereby individual users could test and run programmes much more easily than with conventional input/output media.

The report recommended the purchase of a CDC 6600 central computer, with a set of peripheral computers to pre-treat raw experi• mental data, and the addition at some time of extra storage capacity to cope with the problem of time-sharing with large programmes and many users.

As a result, the CDC 6600 was purchased and installed at CERN early in 1965, and preparations for these various uses were pushed ahead, including the study of the extensions required when on-line uses became common. Programming systems and equipment were studied, and offers were requested from manufacturers for an input/ output processor and for some means of extending the central memory of the 6600 (see Annex, section 4).

Meanwhile, the problem of getting the 6600 into regular use had been much worse than expected, both because of the long delays by CDC in supplying software and because of machine unreliability, which ultimately required a complete overhaul and the retuning of the cen• tral processor in November. Since then, the machine has been working

66/348/5 CERN/SPC/220 Page 2

better and a more efficient operating system has been developed, which should give a speed of-5-6 7090s with HPD in operation at the same time. As a result of these delays, there is a backlog of work, par• ticularly of film to be measured on HPD and Luciole, which will take several months to be run off, even when the new time-sharing system, SIPROS, is in full use. In broad terms, wo can say that we.have lost some six months in bringing HPD and other devices into production, and it will be a difficult job to regain this lost time. Since November, we have also been using a 32 K CDC 3400 (about equivalent to a 7090) lent to us by the firm, and we propose continuing with it until we can make other arrangements for a reserve computer as described in the last section of this paper. This experience has led us to make a complete review of the policy outlined above, including a re-estimate of the future needs of the various users.

For comparison with other laboratories' programmes, wo may recall that Berkeley have just taken delivery of their 6600, and Brookhaven's is due to be installed shortly. Argonne have cancelled their arrangement for an IBM 360/92 and have ordered instead a CDC 6800 for delivery in two years' time. Berkeley will soon also have installed a CDC 6411 to increase the input/output capacity of their 6600, and have an option to buy an extended core store next year.

3. Review of Policy

3.1 Needs

In 1963 the computing load at CERN was estimated to grow from the capacity of 1 IBM 7090 at the end of 1964 to between 10 and 15 7090s by the end of 1968. The detailed bases of these estimates have been reviewed very recently (see Annex, section 2), and the con• clusions are very similar, predicting a load of 8 7090s in mid 1967 and 13 7090s by mid 1968. A large fraction of this load will be provided by on-line devices, either measuring film, or collecting experimental data on the PS, and the size of many of the programmes involved will vary between 40 000 and 70 000 words. At about this time the data rates from on-line experiments could increase still further if a largo data-collecting set-up involving wire chambers or fast hodoscopes were built as part of the improvements programme. Such a project would probably have to include as an integral part a medium-sized computer for data collection and at least partial treatment of the information.

For a work load of this kind, with large programmes and real time uses, it is unlikely that the 6600 as it now stands can have a capacity of more than 10 7090s, even with further develop• ments in compilers and operating systems. To reach the ultimate computing speed of the machine, and to be able to store enough pro• grammes in an accessible form to run several on-line devices and to

66/348/5 CERN/SPC/220 Page 3

begin the use of a multi-access console system, it will be necessary, as foreseen broadly in the 1963 studies, tc add some half a million words of fast-access storage to the 6600 system, and to provide an input/output processor to assemble and edit data on its way to and from the 6600.

The review of needs, and also our practical experience with the 6600, raised two points - the desirability of having extra capacity in the form of a reserve computer, and the amount of time needed for system development work and testing time for now on-line equipment - which were not given sufficient weight in the 1963 studies.

At that time, the need for a medium-sized computer was considered, and rejected on the grounds that it could only add a small extra capacity, and that it would not be useful in adding flexibility of operation when a time-sharing system was operating on the 6600. The poor reliability of the 6600 in the past year, and the difficulty in diagnosis and cure of faults or in installation and testing of improvements (which is intrinsic to any of the new genera• tion of very large and complicated machines), illustrate how important it is that the overall computer facility at CERN should have "fail safe" characteristics, and that therefore the 6600 should be backed up by some independent computer capacity to take care at least of urgent short-term work in case the main machine is out of action, and, possibly, to handle some parts of the production load if circumstances warrant.

Further, although the need to do systems development work at CERN, for the on-line applications and a console system for example, was recognized in 1963, it was then hoped that the initial performance of the 6600 would be good enough - as it would have been if CDC had lived up to their promises on software - to provide easily spare time in 1965-1967 to do this work. Secause of the backlog of work which has built up over the past few months, and the delays in introducing a programming system adequate for our needs, this spare time will not be available. An independent reserve computer would enable development work to be continued, possibly on the second machine, possibly by off• loading the 6600 to some extent, as the 3400 has done over the past three months.

Thus, to the previous requirements of adding extra storage and input/output processing to the present system, we must add the need for some independent computing capacity to act as a reserve in case the 6600 is out of action and to provide extra time for develop• ment work, or to reduce the 6600 load for certain types of work.

66/348/5 CERN/SPC/220 Page 4

3.2 Possible Solutions

Various ways to satisfy these requirements individually are described in the Annex (section 4), Two possibilities for the storage and input/output development emerged from the consideration of manufacturers' replies to our request for tenders for this system, viz. an IBM proposal for a large core store and a 360/50 computer for input/output, and a CDC proposal for an extended core store (ECS) and a 64-05 computer for input/output. The transfer speed between the core store and the 6600 memory would be at least an order cf magnitude faster with the GDC ECS than with the IBM, and the 6405 is several times more powerful as a processor than the 360/50. Further, the machine language, etc. of the 6405 is compatible with that of the 6600, so that it would be feasible to consider a completely integrated system whereby the two computers had equivalent access to the common ECS, with the possibility of either machine operating more or less independently. For the same reason, the system development work could be done almost.entirely on the 6405, whereas with the IBM proposal, time would be needed as well on the 6600, to test out its parts of the system. Since the prices of the two solutions were not significantly different and were within our forecasts, the CDC solution would, other things being equal, be clearly preferable.

However, in either case, the question of reserve - "fail safe" - computing capacity is not solved since the input/output machines, although having a central processor, were not supposed to have either a large local memory (32 K for the 6405 and 8 K for the 360/50) or a normal set of peripherals (tapes, etc.). Ignoring this difficulty, in the case of either machine the question, of reliability must also be raised, for the 6405 because of the recent difficulties with the 6600, and for the 360/50 because it is from an even newer line of machines involving as well a new technology.

To meet fully the "fail safe" requirement by itself, the solution would be a separate machine of well-established type, such as IBM 7094 or CDC 3600, which are known by practical experience at CERN and elsewhere to run very well within their known limitations. To install such a machine at CERN would, for financial and technical reasons, imply at the very least delaying any major development work on the 6600 system for a year, and in practice probably more, so that available capacity would again fall behind demand during 1967 and never catch up thereafter.

A possible way out of this dilemma has been found in the present case: as described in the Annex, it is to extend the memory of the 6405 to 64 K, which would enable it to run most of the CERN programmes, and to hire extra tapes, etc. to make it available as a free-standing machine. This would be an ideal solution, since it would give the independent extra capacity needed without prejudicing

66/348/50 CERN/SPC/220 Page 5

any of the possibilities for developing an extended 6600 system, pro• vided we could be assured of the reliability of the 6415 (= 6405 with 64 K memory). This is an important proviso at this moment, since the 6600, although improved since its overhaul, has not yet run long enough to demonstrate its ultimate reliability, and the 6415, though much simpler in design and construction, uses the same modules and memory stacks. At a recent engineers' visit to the factory where the 6415 is being built and is now running, we have seen that CDC seem to have learnt the lesson of the troubles with the laboratory-built 6600s and have much tighter quality control on components and better tuning-up pro• cedures. This would, however, not be enough to make us feel safe in proposing the 6415 at this moment, but we believe we can work out with CDC a proposal whereby we would be able to run our programmes under production conditions for a month or more on the 6415 at the factory before delivery, and if wo were not by then satisfied with the perfor• mance and reliability of the 6600 series, to exercise an option to take instead a conventional CDC 3800* in September to provide at least some reliable reserve capacity while other arrangements were made.

The second part of the improvement plan would be the extended core store; originally it had been hoped to take delivery early in 1967, but the delays we have already experienced in our programme mean that this date must be postponed. This will also enable us to be more sure on its performance and reliability before definitely accepting it, and for this reason we should only at this time arrange with CDC for an option to purchase during 1967.

Financially, as can be seen from the Annex, the 6415 and peripherals will amount to the sum that was foreseen in our budget estimates for computer development in 1966, 1967; the extended core store is in any case delayed, and will be covered in the 1968 budget. This programme of expenditure amounts to 2.5 million Swiss francs per year, i.e. about 12% of the cost of the central computer, which is very much in line with what is found necessary with other large general-purpose instruments like accelerators or bubble chambers if they are to be kept up to date, and seems now to bo inevitable in the computer field also.

It must be recognized that the computing needs of high-energy physics are developing so fast, and will continue to do so in future, that the demands of the large laboratories are in these days outstripping the ability of manufacturers to provide powerful enough computers of proven performance in the field and with adequately tested all-purpose operating systems to cope with their full work load. CERN and similar laboratories must from now on face a continuing research and development programme into computer use and system design, for both small and large machines, in the way some atomic energy laboratories have done in the past, so as to be able to use the most up-to-date equipment as soon as it becomes available and to adapt it to their rather specialised needs.

* The CDC 3800 is the replacement for the 3600, which is no longer in production: sec Annex, section 4. 66/348/5 ANNEX

Report on Present Status and Future Requirements of the CERN Computing Facilities

(66/348/3/ga) CERN - Data Handling Division

DD/CO/66/1 28 February, 1966 G.R. Macleod

Report on Present Status and Future Requirements of the CERN Computing Facilities

1. Introduction

The Report of the European Committee on the Future Computing Needs of CERN (CERN 516) was presented to Council in December 1963. The policy recommended in that report was made up of three parts. Firstly that a substantial increase in the capacity of the central computing installation be made available over the period 1964 - 69 in order to provide for the predicted growth in the computing needed for analysis of experimental data Secondly, that facilities be provided to meet the needs of newly developing experimental techniques involving computers (notably flying spot digitizers, on-line control of measuring tables, and on-line counter and spark chamber experiments). Thirdly, that the poten• tialities of time-sharing techniques be exploited to stimulate the use of computers as a day-to-day tool of the scientific staff of the laboratory.

To implement this policy, the Report recommended the immediate purchase of a large multi-programming computer, the Control Data 6600, as the central computing facility. It was recognised that to fulfil the policy in the above time-scale a considerable amount of computer system development work would have to be undertaken at CERN. By acquiring such a large machine straight away it was hoped to provide the additional capacity to allow the development to proceed over the first year or so without hindering the other computing work of the laboratory. The Report recommended the purchase of a number of small data-acquisition computers to be connected by data-links to the 6600 to meet the needs of real-time data analysis and finally further proposed the development of a multiple access time-sharing system of remote consoles to radically reduce turn• around time for users testing and running programmes. It foresaw the purchase of additional peripheral devices, storage, data-links, and ter• minal equipment in order to develop the 6600 installation to fulfil the policy outlined.

The 6600 was installed in January 1965. The difficulties encount• ered in getting the computer fully operational have been considerably greater than either CERN or Control Data foresaw, with the result that we have been

(66/348/3/ga) 2

seriously short of on-site computing capacity over the last twelve months, and our development staff has beev. fully occupied by day-to-day problems. This has resulted in a general slowing-down in many aspects of the labo• ratory's programme, and, although recent hardware and software developments on the 6600 are expected to provide adequate capacity to meet our immediate needs in the course of the next few months, the situation warrants a detailed re-examination.

The purpose of the present paper is therefore to review the present and future computing needs of the laboratory in the light of our experience with the 6600, to examine in what respects the previously adopted policy might have to be modified, and what particular additional peripheral and terminal computing equipment is needed.

2. Estimates of Required Computing Capacity

The estimates made in 1963 (CERN 516) of required total capacity were, in units of IBM 7090,- 1 by end 1964, 3 to 5 by end 1966 and 10 by 1968. The revised estimates made in January 1966 are, in the same units, 5 in 1966, 8 by mid-1967 and about 13 by mid-1968 (see figure 1 ) .

The new estimates show a similar growth to the previous ones, with a somewhat higher absolute.value due largely to increased data-collection possibilities in counter experiments using wire chamber arrays. However, it must be noted that the previous 1963 estimates allowed for an increase in computing capacity per scientist required when a multiple-access remote console system-would be introduced in 1967-68. The 1966 estimates are based'on users estimates of their requirements using conventional computing methods, and therefore suggest a higher growth rate than foreseen for conventional computing, As our development programme is now running about 1 year later than planned; this then raises the question of whether enough central computing capacity can be available on the 6600, even with the extensions considered below, to introduce more than a pilot scheme for the use of remote consoles on the 6600.

These estimates are essentially dominated by the needs of. the NP and TC divisions who expect to use about 1/3 each of the available capacity in 1966 and 1/2 and 1/3 respectively in 1968. The NP requirements have, been based upon reasonable assumptions as to the number of counter experiments which will be run on the CERN accelerators over the next three years, taking into account the requirements for flying spot digitizer measurement of spark chamber film, the introduction of wire chamber techniques and the small on• line computers foreseen for this period. The TC requirements are based on the assumption of an annual production of about 3 million pictures a year from the present chambers over the next three years From the 20 - 2.5% of these pictures which will be analysed at CERN it is expected to measure some 300, 600 and 900 thousand events in 1966, 67 and 68 respectively. This increase is to be made possible by using the increased measuring capacity expected from the on-line Iep factory and the operation of the flyng spot

(66/348/3/ga) 3

digitizers to process more frequently occuring.types of events than has been possible up to now. For efficient operation the THRESH-GRIND-SUMX analysis programmes now require a computer with 64 thousand word memory. The growth in programme size beyond thy 30 thousand words used on the CERF IBM 7090 is due partly to an increase in the complexity of the computations made, and partly due to the writing of the programmes in CERN Fortran in order to maintain compatibility with computers used in Member State labora• tories. The flying spot digitizer programmes need around 40 K memory, but the central processor is required for only a few percent of the overall time taken to scan the film. Developments of the flying spot digitizer techniques to minimum guidance will probably increase the memory requirements to 60 - 70 K, with a central processor usage of between 10 and 20% of the overall time. The present trend, which will probably continue, is that "physics" computations (phase space, minimisation, Monte-Carlo calculation etc.), together with preparatory calculations for an experiment (beam, design, chamber optical constants, kinematics tests etc), require in addition about half as much capacity as the regular production computing.

The remainder of the estimated capacity, 1/3 in 1966 falling perhaps to 1/6 of the total in 1968 is typically straight forward calculations requiring only limited amounts of input/output, and which can be processed within 20 - 30 K of memory.

The predictions for 1969 and beyond are clear only in one respect, viz. that they will considerably exceed the capabilities of any of the currently available large scientific computers. By this period large wire chamber arrays, fast cycling or giant bubble chambers may be in, or enter• ing into, regular operation, with very large increases in data taking rates implying increases in data analysis capacity required. Remote console operation of computers will also be an accepted technique by this time with a resulting increase in the amount of computing capacity which the individual scientist will be able to use usefully. The nest generation of large machines, GDC 6800, IBM 360/90 series and such like will just be becoming available. The capital repayments to the Swiss Confederation of the loan for the purchase of the 6600 are planned to be completed by mid-1969, and the additional capacity required for 1969-70 and beyond must be provided for by a new computer. During this period the load on the 6600 will remain very heavy, since we must allow for a considerable overlap period during which established work on the 6600 continues undisturbed whilst a completely new system is built up. It is clear that by 1968 - 69 CERN will have many problems which demand a computer capable of doing large amounts of work using large programmes, and that, although this is not made explicit in the above statistics, there will be a strong need to provide some kind of programmer operated system with multiple- access consoles to enable the writing, testing and use of these large pro• grammes to be done conveniently.

It is clear, also, both from the growing dependance on computing of the whole experimental programme of the laboratory which these estimates show, as well as the difficulties experienced during the past twelve months, that the available capacity must in future have some fail-safe characteristic.

(66/348/3/ga) 4

A secondary computer must be permanently available which, in the event that some essential and major part of the main computing capacity be out of the action for periods even of a few days, can be used to keep some computing service.available for the most urgent work.

3. The 6600 Computer - Status and Potential

An account of the performance and limitations of ; the 6600 from its delivery.up to.the end of 1965 was given in CERN/SPC/214, which reproduced the relevant six-monthly progress reports of the Data Handling Division.

3.1 Present situation

The various engineering modifications made since last October, have improved the performance of the main frame (central processor, central memory, peripheral processors and channels) of the computer. Satisfactory voltage and timing margins now exist indicating the machine is more stable and no longer just "on the edge". The unscheduled maintenance required on the main frame is now regularly below 10% of the 130 hours per week scheduled operating time. Two main problems remain. Firstly the disquieting fact that some of the faults appear as "intermittents" occurring apparantly randomly a few times per day and this situation often exists for several days or weeks before the fault can be sufficiently diagnosed for the engineers to cure it. Secondly, in the light of our experience last October when the computer became unuseable after it had been in regular operation during June and July, it is, at present, too early to say whether the engineering changes or the individual component performance are such as to guarantee the long-term reliability which we must have. Improved dia• gnostic programmes and maintenance procedures (both promised shortly by Control Data) together with the now reasonable margins on the machine and the-growing experience of ±he maintenance crew suggest that these problems should diminish, but several months more running are needed to establish this.

The general performance of the peripheral devices (card reader and punch, printers, discs and magnetic tapes, multiplexor and teletypes) is also improved since last October. However, the performance of individual items is still such that it is usual for some piece of equipment to be needing attention. As there is no means by which the engineers can test peripheral equipment fully except by using the 6600, we are too often faced with running the computer with some known unreliable peripheral as it ie too expensive to stop all computing to allow the engineers to take the 6600 to repair a particular device which many jobs can do without. This situation should improve with the better maintenance which will come with growing experience; the testing problem will not be appreciably reduced until some off-line testing device is available for peripherals. This is promised.by Control Data for the second half of 1966.

(66/348/3/ga) 5

In conclusion, the general performance of the 6600 hardware is now back to what it was last summer, engineering modifications correcting certain faults in the original design have been installed and there is reason to suppose that its reliability will slowly improve. Other 6600 installations have had similar overhauls, and at tho last 6600 users meeting, which was held in CERN in January, no serious complaints on reliability were made by other users.

The computing service on the 6600 is, at present, using some 13 hours per day under the serial processing Interim System, which gives us about the equivalent of 1.5 - 2 IBM 7090's on site. The multi-programming system SIPROS, which has been largely rewritten and improved by the joint efforts of the CERN system programmers and the CDC support group at CERN. is now going into general use, having been used for a two-hour period each day since mid-January. Preliminary estimates suggest that SIPROS gives an approximate gain of a factor two in throughput over the Interim System. It will also allow the flying spot digitizers to operate many hours per day, multi-programmed with other work. We therefore expect over the course of the next 2 to 3 months to extend the computing service using the multi-programmingoperating system to reach a capacity equivalent to at least 6 full time IBM 7090's.

3.2 Potential capacity

By the use and steady improvement of a multi-programming system on the present 6600 installation; its throughput may be expected to increase rather rapidly during 1966 to a level between 7 and 15 times an IBM 7090 depending on the type of work load. Tho uncertainty in this figure, which apparently means uncertainty in the time at which the 6600 would become saturated between mid-1967 and the end of 1968, is a reflection of the impossibility of summing up the capacity of a computer in a single figure without some reference to the kind of work it is having to do and the suitability of its operating system to that kind of work.

The effective capacity of a time-sharing computer can, in fact, drop if the work-load changes in such a way as to add many jobs with some unfavourable characteristics. Unless some additional hardware and software is made available for the 6600, then the addition of more than a very few real-time and remote terminal applications will, in fact, appreciably reduce the overall throughput. For the production and programme testing work, the present requirement is for a few large, long-running background jobs of sizes up to about 60 thousand words time-shared with a lot of smaller short-running jobs. For this kind of work-load a throughput of 10 times an IBM 7090 or more could easily be achieved by mid-1967 with the present configuration and an efficient operating system. Over the next few years, however, we expect the number of real-time applications to increase. For these applications large programmes have to be available in memory to process the data from the real-time sources, such as EPD and on-line experiments, even through the total usage if the

(66/348/3/ga 6

central processor may be small. If many of these applications were introduced on to the present 6600 configuration, the size of the programmes would in fact prevent other programmes, which could use the central processor time not required by the real-time programmes, being in memory at the same time. In this way they would effectively cause an increase in the time the.central processor would be idle, hence reducing the overall throughput of the computer. The addition of a large fast storage to the 6600 would however allow effecient use to be made of the cental processor even when a large proportion of real-time jobs were added into the work-load. Such storage would allow the rapid transfer into memory of programmes able to use the central processor in the short intervals when the real-time programmes would be unable to do so, and also the rapid restoring of the realtime programmes at the request of external devices.

It should be noted that as the complexity and sophistication of the calculations necessary to analyse high energy data increases, so do the programme sizes. This has clearly happened over the last few years and the trend will continue. It is likely therefore, even for the needs of the general production and programme testing load, that addition of a fast access memory to the 6600 will be necessary by 1968. This general trend also implies that if independant computers are used for individual applications the memory sizes required tend to increase with time. For this reason any computer expected to fulfil a back-up rôle at CERN, or foreseen to take part of the production load off the 6600 must now have a 64 thousand word memory

With several real-time devices, and many remote terminals operating concurrently with programmes requiring magnetic tapes, printers reader and punch, the input/output demands become very heavy. The 10 peripheral processors on the 6600 are not sufficient to handle a complex flow of realtime data and carry out editing functions as well as their system control functions. These problems can be overcome by the introduction of an input/ output processor between the data sources and the 6600 in order to control the data flow to and from the main computer, and to prepare programmes and data in a way most suited to the efficient use of the 6600.

These conclusions, based on one years practical experience of the use of the 6600, are in general agreement with the analysis made in 1963, and manufactures were asked last year to submit offers for suitable mass storage and input/output processors to enable us to put such a development policy into practice. Our recent experience shows that we should consider also making the additional equipment serve to increase our normal capacity in the near future, in order to give time for development work, and also to provide a "fail-safe" reserve to protect against possible future break-downs in the 6600. The next sections describe possible solutions to this equipment problem.

(66/348/3/ga) 7

4. Possible Additional Equipment

The possible alternative choices of computer equipment which could satisfy the needs outlined in the previous sections are listed and discussed below. This information is based on the tenders submitted during last year and on subsequent discussions with manufacturers,

4.1 Mass storage

The Ampex Corporation have proposed a 512 thousand word mass core memory with 1 .5 μsec access time and 2.5 μsec cycle time and 72-bit words length. Delivery time is about S to 12 months and price 3.51 MFr. The memory would be connected to a 6600 data channel via a special interface. The maximum rate of transfer of the data channel would not permit to use the full speed of the memory. The cost is rather high compared to other offers.

IBM proposed their Large Capacity Storage with 512 thousand words of 64 bits. The access time is 3 μsec with a cycle time of 8 μsec. They propose to provide a special interface to connect the device to a 6600 data channel, and the necessary code conversion between CDC and IBM standards would be accomplished by hardware within this interface. This connection would give a transfer rate of between 6 and 13 μsec per word (depending on the amount of overlapping possible) into the 6600 central memory. With recent advances in core-memory technology it seems very probable that IBM will be developing a faster large core store, but they are neither able to quote nor give any information for this. Delivery is from 12 to 18 months. The price quotation was made in the form of an overall price for the mass store and input/output processor (see next section). The portion of this for the mass store is 2.06 MFr., though if bought separately the cost would almost certainly be higher.

Control Data proposed their Extended Core Storage. Thi3 store will have a direct connection to the 6600 Central Memory, thus avoiding the limit in maximum transfer rate set by the 6600 data channel for the IBM and Ampex memories, and will have a capacity of 512 thousand 60-bit words. Being designed for the 6600 a special interface is not necessary. The memory itself has a 1 μsec cycle time, but by the use of parallel operation a maximum transfer rate of 0.1 μsec per word is to be achieved in this respect it is technically superior to the IBM memory. However, it is a new development involving certain new techniques, and after a recent visit of CERI staff to Minneapolis to inspect this project, we feel that it would be unwise to count on reliable production models being available before the second half of 1967, even though Control Data quote end 1966 delivery. Again the price quoted was an overall price for mass store and input/output processor; the price for the mass store within this quotation is 1.93 MFr.

(66/348/3/ga) 8

4.2 Input/output processor

IBM proposed a model 50 of the. new IBM System 360 as an input/ output processor. The large core store would be connected between the 6600 and the Model 50, both machines having access to any part of the store. Flying spot digitizers, PS data-links, and remote consoles would be attached to the input/output processor which would channel data into the large core store, where it would await processing by the 6600. The overall net price for Model 50 plus large core store quoted by IBM is 3.20 MFr. with about 12-18 months delivery. A special operating system would have to be developed at CERN to use this configuration. The possibility to increase the power of the system by subsequently upgrading the Model 50 to a larger number of the IBM 360 series is somewhat offset by uncertainty as to whether the mass core can be similarly upgraded, and the difficulty in increasing correspondingly the speed of transfer into the 6600.

Control Data proposed the 6400 as an input/output processor in a very similar configuration with their extended core storage between the 6600 and the 6400. The overall price for the mass storage and 6400 comes to 3.86 MFr. with delivery of the 6400 in summer 1966. The computing power of this configuration would be very significantly more than the. IBM system, due to the higher transfer speeds of the core store and the power of the 6400 which probably has at least three times the computing capacity of the Model 50. The core store is probably not available, however, for another. 18 months, though the 6 month delivery of the 6400 would allow an early start to be made on development work for the special operating system.which would be necessary.

From the point of view of performance this solution would be preferable to the others proposed. Its price is not significantly different from the IBM proposal, and the very early delivery of the 6400 would be a distinct advantage.

4.3 Stand-alone computers

The need to provide some secondary "fail-safe" computer capacity may be. met either by having a proven medium sized computer on site as a stand-alone machine which would take some well defined part.of the computing load off the 6600, or to.have a second computer compatible with the 6600 on which certain work could be run in the event of break-down or continued unreliability of the 6600. Either alternative would provide the spare capacity which is needed to carry out the necessary developments on the 6600.

The machines which can be considered in this context are IBM 7094 II CDC 3800 and CDC 6400, These are all machines with the capacity (about 2 to 4 × IBM 7090) to be able to process a considerable fraction of the regular production load, and are available on short delivery.

(66/343/3/ga) 9

The IBM 7094 II is a well-tred machine with a capacity about double the IBM 7090. The rental cost over two years would be about 6.6 MFr. and although no longer manufactured, a second-hand machine might be available in'6 - 12 months. This computer does not have a 64 thousand word continuously addressable memory which is required by the bubble chamber analysis programmes.

The Contral Data 3800 is the successor to the 3600; this latter is no longer manufactured, nor do Control Data expect any to be returned within the next twelve months. The 3800 is very similar to the 3600, except that the speed of the logic circuitry has been slightly increased, and new memories of 0.8 μsec will be available (though not with first deliveries which will have 3600 type memories). The 3600 used at Paris over the last few months for some CERN production work has been shown to be very reliable; the 3800 may be expected to be equally reliable, though one should not discount the possibility that a few teething troubles might result from the speeded up logic and memory. Delivery could be made in September 1966, and the two year cost of rental would be about 4.75 MFr,. Purchase of the main frame would cost 4.65 MFr., to which should be added rental cost of peripheral equipment leading to a total expenditure of about 5.8 MFr. over two years. However, the annual cost for third and successive years would be 2.38 MFr. for complete rental as compared with 0.58 MFr. for the case with purchase of the main frame.

The CDC 6400 is the small machine in the Control Data 6000 series. It is made of the same components as the 6600, has identical channels and peripheral processors, with a simplified serial central processor and is available with 32, 64 or 128 K memory. Delivery could be made in June, and purchase of the main frame with 64 K memory would cost 4.36 MFr.; with annual rental for the peripheral equipment of 0.73 MFr. this would lead to a total expenditure of 5.82 MFr. over two years. The difference between this price and the 1.93 MFr. cost of the 6400 as an input/output processor is due entirely to the requirement of 64 K memory and magnetic tapes, printer, reader and punch peripheral equipment for a stand-alone computer. The annual cost of rental for the whole machine would be 2.58 MFr. This machine is built at the Arden Hills Computer Division of Control Data, and not at the Chippewa Research Laboratories where our 6600 was made. Recent visits by CERN staff to Arden Hills where a 6400 is now operating lead us to believe that the lessons of standard production techniques and quality control on components have been learnt from, 'the 6600 experience and applied to the 6400. The simpler central processor should also be easier to maintain and diagnose than the 6600.

The rental conditions for the 3800 are unfavourable if the machine were taken for more than 1 year. Purchase of 3800 or 6400 with rental of peripherals costs about the same over two years. With the 3800 one has a machine of known performance, without possibilities of increasing its capacity in the long run. With the 6400 one has a machine compatible with the 6600 which can be integrated into an overall programme for increasing

(66/348/3/ga) 10

the capacity of the central .computing instillation to meet the longer-term needs, as well as providing appreciably more capacity as a stand-alone computer than the 3800. It is, however, a new machine and.can only be considered if adequate arrangements can be made with Control Data to process a significant amount of CERN production work on the machine at Arden Hills before delivery, in order to have a practical demonstration of its performance.

Conclusion

To meet the expected needs of the laboratory over the period to 1969 it will be necessary to augment the 6600 installation by the addition of extra memory and an input/output processor. Recent experience shows it essential also to have some separate or compatible secondary computing capacity on site.

Technically the best way to meet the first requirement is the Control Data proposal of Extended Core Storage and 6400. To meet the second requirement the 6400 could be obtained this year as a stand-alone machine, subject to satisfactory proofs of the 6000 series reliability, and the extended core storage added towards the end of 1967 with payment in 1968. This plan would meet the budgetary provision of approximately 2.5 MFr. per year foreseen for computer developments over 1966 - 68.

If proof is not available of the 6000 series reliability, then a 3800 could meet the requirement of a secondary computer. It would provide adequate reliable capacity to satisfy the needs of some part of.the production load for two years or so, but it would not augment the central computing capacity in the way needed to meet the requirements of 1968 - 69.

(66/348/3/ga) Fig. 1

/66/54