47:
228:-based systems, building two small machines to test various techniques. This was clearly the way forward, and in the autumn of 1956, Kilburn began canvassing possible customers on what features they would want in a new transistor-based machine. Most commercial customers pointed out the need to support a wide variety of peripheral devices, while the
283:
renting out time on the
University's Mark 1. Soon after the project started, in October 1958, Ferranti decided to become involved. In May 1959 they received a grant of £300,000 from the NRDC to build the system, which would be returned from the proceeds of sales. At some point during this process, the machine was renamed Atlas.
346:(Harwell) in December 1964. The AEA machine was later moved to the Atlas Computer Laboratory at Chilton, a few yards outside the boundary fence of Harwell, which placed it on civilian lands and thus made it much easier to access. This installation grew to be the largest Atlas, containing 48 kWords of 48-bit
282:
In spite of all this effort, by the summer of 1958, there was still no funding available from the NRDC. Kilburn decided to move things along by building a smaller Muse to experiment with various concepts. This was paid for using funding from the Mark 1 Computer
Earnings Fund, which collected funds by
740:
From the outset, Atlas was conceived as a supercomputer that would include a comprehensive operating system. The hardware included specific features that facilitated the work of the operating system. For example, the extracode routines and the interrupt routines each had dedicated storage, registers
385:
numbers in about 1.59 microseconds, while STRETCH did the same in 1.38 to 1.5 microseconds. Nevertheless, the head of
Ferranti's Software Division, Hugh Devonald, said in 1962: "Atlas is in fact claimed to be the world's most powerful computing system. By such a claim it is meant that, if Atlas and
330:
By the mid-1960s the original machine was in continual use, based on a 20-hour-per-day schedule, during which time as many as 1,000 programs might be run. Time was split between the
University and Ferranti, the latter of which charged £500 an hour to its customers. A portion of this was returned to
290:
was proceeding. However, the
Supervisor operating system was already well behind. This led to David Howarth, newly hired at Ferranti, expanding the operating system team from two to six programmers. In what is described as a Herculean effort, led by the tireless and energetic Howarth (who completed
208:
Through 1956 there was a growing awareness that the UK was falling behind the US in computer development. In April, B.W. Pollard of
Ferranti told a computer conference that "there is in this country a range of medium-speed computers, and the only two machines which are really fast are the Cambridge
605:
One feature of the Atlas was "Extracode", a technique that allowed complex instructions to be implemented in software. Dedicated hardware expedited entry to and return from the extracode routine and operand access; also, the code of the extracode routines was stored in ROM, which could be accessed
428:
In architecture, the
Manchester Atlas was exemplary, not because it was a large machine that we would build, but because it illustrated a number of good design principles. Atlas was multiprogrammed with a well defined interface between the user and operating system, had a very large address space,
393:
that the Atlas was significantly bested. CDC later stated that it was a 1959 description of Muse that gave CDC ideas that significantly accelerated the development of the 6600 and allowed it to be delivered earlier than originally estimated. This led to it winning a contract for the
386:
any of its rivals were presented simultaneously with similar large sets of representative computing jobs, Atlas should complete its set ahead of all other computers.". No further sales of LARC were attempted, and it is not clear how many STRETCH machines were ultimately produced.
380:
Atlas had been designed as a response to the US LARC and STRETCH programs. Both ultimately beat Atlas into official use, LARC in 1961, and STRETCH a few months before Atlas. Atlas was much faster than LARC, about four times, and ran slightly slower than STRETCH - Atlas added two
96:, in use from 1962 (when it was claimed to be the most powerful computer in the world) to 1972. Atlas's capacity promoted the saying that when it went offline, half of the United Kingdom's computer capacity was lost. It is notable for being the first machine with
368:, and in return, the University would use these to develop a cheaper version of the system. The result was the Titan machine, which became operational in the summer of 1963. Ferranti sold two more of this design under the name Atlas 2, one to the
331:
the
University Computer Earnings Fund. In 1969, it was estimated that the computer time received by the University would cost £720,000 if it had been leased on the open market. The machine was shut down on 30 November 1971.
510:(B-lines) that could be used for address modification in the mostly double-modified instructions. The register address space also included special registers such as the extracode operand address and the exponent of the
271:(NRDC), responsible for moving technologies from war-era research groups into the market. Over the next eighteen months, they held numerous meetings with prospective customers, engineering teams at Ferranti and
715:, and ABL (Atlas Basic Language, a symbolic input language close to machine language). Being a university computer it was patronised by a large number of the student population, who had access to a protected
1587:
210:
232:
suggested a machine able to perform an instruction every microsecond, or as it would be known today, 1 MIPS of performance. This later request led to the name of the prospective design, MUSE, for
621:
was set to zero, this was an ordinary machine instruction executed directly by the hardware. If the uppermost bit was set to one, this was an
Extracode and was implemented as a special kind of
668:
procedures. Typical examples would be "Print the specified character on the specified stream" or "Read a block of 512 words from logical tape N". Extracodes were the only means by which a
209:
EDSAC 2 and the
Manchester Mark 2, although both are still very slow compared with the fastest American machines." This was followed by similar concerns expressed in May report to the
1296:
179:
The University of Manchester's Atlas was decommissioned in 1971. The final Atlas, the CADCentre machine, was switched off in late 1976. Parts of the Chilton Atlas are preserved by
243:, for instance, will spend the vast majority of its time waiting for the reader to send in the next bit of data. To support these devices while still making efficient use of the
446:
The machine had many innovative features, but the key operating parameters were as follows (the store size relates to the Manchester installation; the others were larger):
1577:
1567:
729:
It also had a programming language called SPG (System Program Generator). At run time an SPG program could compile more program for itself. It could define and use
268:
402:
1261:
1243:
369:
343:
1518:
521:
registers: 125 was supervisor (interrupt) control, 126 was extracode control, and 127 was user control. Register 0 always held value 0.
1562:
1499:
1480:
1223:
1118:
819:
307:
The first Atlas was built up at the university throughout 1962. The schedule was further constrained by the planned shutdown of the
122:
456:. A word could hold one floating-point number, one instruction, two 24-bit addresses or signed integers, or eight 6-bit characters.
1552:
1294:
T. Kilburn; D.B.G. Edwards; D. Aspinall (September 1959). "Parallel addition in digital computers: A new fast 'carry' circuit".
920:
1582:
188:
1095:
846:
421:
239:
The need to support many peripherals and the need to run fast are naturally at odds. A program that processes data from a
164:
operating system developed by Cambridge University Computer Laboratory. Two further Atlas 2s were delivered: one to the
645:
173:
1052:
745:
from user mode to extracode mode or executive mode, or from extracode mode to executive mode, was therefore very fast.
1557:
1157:
115:
30:
This article is about a British supercomputer. For the early American codebreaking computer also known as Atlas, see
1429:
Proceedings of the December 12–14, 1961, Eastern Joint Computer Conference: Computers - Key to Total Systems Control
433:
In June 2022 an IEEE Milestone was dedicated to the "Atlas Computer and the Invention of Virtual Memory 1957-1962".
401:
Ferranti was having serious financial difficulties in the early 1960s, and decided to sell the computer division to
46:
551:
108:
1153:
733:. Its variables were in <angle brackets> and it had a text parser, giving SPG program text a resemblance to
1572:
766:
492:
words of read-only memory (referred to as the fixed store). This contained the supervisor and extracode routines.
276:
180:
142:
730:
221:
1134:
319:. It was not until January 1964 that the final version of Supervisor was installed, along with compilers for
514:
365:
244:
229:
153:
633:
being determined by the other nine bits. About 250 extracodes were implemented, of the 512 possible.
575:
315:, director of the AEA. This system had only an early version of Supervisor, and the only compiler was for
291:
his Ph.D. in physics at age 22), the team eventually delivered a Supervisor consisting of 35,000 lines of
555:
410:
359:
165:
157:
79:
734:
311:
machine at the end of December. Atlas met this goal, and was officially commissioned on 7 December by
754:
618:
568:
561:
533:
478:
372:(Aldermaston) in 1963, and another to the government-sponsored Computer Aided Design Center in 1966.
335:
138:
60:
1527:
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and 32 tape drives. Time was made available to all UK universities. It was shut down in March 1974.
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692:
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578:
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http://bitsavers.informatik.uni-stuttgart.de/pdf/ict_icl/atlas/ (Several reference documents)
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and introduced the notion of extra codes to extend the functionality of its instruction set.
308:
296:
248:
213:
Advisory Committee on High Speed Calculating Machines, better known as the Brunt Committee.
1317:
F. H. Sumner; G. Haley; E. C. Y. Chen. "The Central Control Unit of the "Atlas" Computer".
1233:
1522:
518:
406:
112:
835:"COMPUTERS AND CENTERS, OVERSEAS: 2. Ferranti Ltd., Atlas 2 Computer, London Wl, England"
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696:
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511:
507:
500:
417:
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The Atlas was highly regarded by many in the computer industry. Among its admirers was
382:
312:
97:
247:(CPU), the new system would need to have additional memory to buffer data and have an
1546:
664:. But about half of the codes were designated as Supervisor functions, which invoked
529:
467:
93:
926:
716:
700:
699:, which was contemporary to Algol 60 and created specifically to address what
499:(eqv. to 576 KB), split across four drums but integrated with the core store using
161:
1537:
470:
that embraced supervisor ('sacred') store, V-store, fixed store and the user store
286:
The detailed design was completed by the end of 1959, and the construction of the
676:, had similar mechanisms for calling on the services of their operating systems.
672:
could communicate with the Supervisor. Other UK machines of the era, such as the
1359:"The Manchester University Atlas Operating System Part I: Internal Organization"
1327:
834:
684:
Atlas pioneered many software concepts still in common use today, including the
661:
582:
547:
and extracode routines, by reading and writing special wired-in store addresses.
496:
347:
264:
260:
240:
217:
31:
1394:"The Manchester University Atlas Operating System Part II: Users' Description"
622:
525:
225:
118:
17:
1462:
1445:
1419:
1410:
1393:
1384:
1375:
1358:
1342:
1309:
1207:
703:
perceived to be some defects in Algol 60. The Atlas did however support
688:, "considered by many to be the first recognisable modern operating system".
1436:
1326:
Kilburn, T.; Edwards, D. B. G.; Lanigan, M. J.; Sumner, F. H. (April 1962).
657:
637:
544:
453:
184:
1096:"Milestones:Atlas Computer and the Invention of Virtual Memory, 1957-1962"
558:
to determine whether the desired virtual memory location was in core store
334:
Ferranti sold two other Atlas installations, one to a joint consortium of
1142:. London: International Computers and Tabulators Limited. p. 12.1/1.
1136:
I.C.T. Atlas 1 Computer Programming Manual for Atlas Basic Language (ABL)
704:
482:
390:
320:
316:
287:
126:
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in Australia, which had originally been in discussions to buy an Atlas.
708:
405:(ICT) in 1963. ICT decided to focus on the mid-range market with their
324:
130:
1270:
Bell, C. Gordon; Kotok, Alan; Hastings, Thomas; Hill, Richard (1978).
259:
When the Brunt Committee heard of new and much faster US designs, the
1427:
T. Kilburn; R.B. Payne; D.J. Howarth (1962). "The Atlas Supervisor".
614:
450:
233:
192:
146:
101:
1528:
The Atlas Supervisor paper (T Kilburn, R B Payne, D J Howarth, 1962)
712:
489:
474:
395:
364:
In February 1962, Ferranti gave some parts of an Atlas machine to
187:; the main console itself was rediscovered in July 2014 and is at
169:
1297:
Proceedings of the IEE - Part B: Radio and Electronic Engineering
104:
techniques; this approach quickly spread, and is now ubiquitous.
653:
571:— so performance measurements were not easy, but as an example:
524:
Capability for the addition of (for the time) sophisticated new
1196:
Resurrection: The Bulletin of the Computer Conservation Society
596:
Floating-point multiply, double modify – 4.97 microseconds
567:
Atlas did not use a synchronous clocking mechanism — it was an
160:, or Atlas 2, it had a different memory organisation and ran a
610:
272:
463:
that used novel circuitry to minimise carry propagation time.
121:. Atlas was created in a joint development effort among the
1279:
Computer Engineering: A DEC View of Hardware Systems Design
339:
134:
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1032:
1030:
1028:
991:
989:
987:
974:
972:
947:
945:
943:
593:
Floating-point add, double modify – 2.61 microseconds
251:
that could coordinate the flow of data around the system.
1588:
Department of Computer Science, University of Manchester
1444:
D. J. Howarth; P. D. Jones; M. T. Wyld (November 1962).
648:
which would have been too inefficient to implement in
100:(at that time referred to as "one-level store") using
1256:(2 ed.), Swindon: The British Computer Society,
1082:
757: – Series of stored-program electronic computers
466:
24-bit (2 million words, 16 million characters)
409:, a flexible range of machines based on the Canadian
1319:
Information Processing 1962, Proc. IFIP Congress '62
74:
66:
56:
168:Centre in Cambridge (later called CADCentre, then
152:A derivative system was built by Ferranti for the
51:The University of Manchester Atlas in January 1963
722:Several of the compilers were written using the
211:Department of Scientific and Industrial Research
613:of a 48-bit Atlas machine instruction were the
503:. The page size was 512 words, i.e. 3072 bytes.
485:), featuring interleaving of odd/even addresses
426:
133:. Two other Atlas machines were built: one for
1473:The First Computers: History and Architectures
1159:The I.C.T. Atlas I Computer Programming Manual
539:Peripheral control through V-store addresses (
267:, they were able to gain the attention of the
590:add, no modification – 1.61 microseconds
299:to solve the problem of peripheral handling.
8:
1538:Ferranti Atlas 1 & 2: List of References
39:
644:today. They were used to call mathematical
925:, University of Manchester, archived from
726:, considered to be the first of its type.
45:
38:
1461:
1409:
1374:
1238:, Swindon: The British Computer Society,
1172:
1070:
1038:
1019:
1007:
995:
978:
963:
951:
907:
895:
883:
871:
859:
797:
785:
275:, and design teams at Manchester and the
269:National Research Development Corporation
1335:IRE Transactions on Electronic Computers
1578:Collection of National Museums Scotland
1471:Raúl Rojas; Ulf Hashagen, eds. (2000).
1154:"12. Further Facilities and Techniques"
778:
724:Brooker Morris Compiler Compiler (BMCC)
625:jump to a location in the fixed store (
389:It was not until 1964's arrival of the
1568:Computer-related introductions in 1962
1111:Computer Architecture and Organization
812:Computer Architecture and Organization
403:International Computers and Tabulators
636:Extracodes were what would be called
370:Atomic Weapons Research Establishment
174:Atomic Weapons Research Establishment
7:
344:Atomic Energy Research Establishment
1516:The Atlas Autocode Reference Manual
517:. Three of the 128 registers were
25:
1492:A History of Computing Technology
1254:A History of Manchester Computers
1235:A History of Manchester Computers
849:from the original on 3 June 2018.
1133:Cronin, D.E. (31 January 1965).
1494:. IEEE Computer Society Press.
1431:. Macmillan. pp. 279–294.
1392:Howarth, D. J. (1 March 1961).
1218:, Manchester University Press,
1192:"Designing and Building Atlas"
763: – First operating system
189:Rutherford Appleton Laboratory
1:
1446:"The Atlas Scheduling System"
695:available on Atlas was named
422:Digital Equipment Corporation
92:was one of the world's first
1357:Kilburn, T. (1 March 1961).
1190:Edwards, Dai (Summer 2013),
606:faster than the core store.
342:in 1963, and another to the
224:had been experimenting with
839:Digital Computer Newsletter
1604:
1328:"One-Level Storage System"
552:content-addressable memory
534:direct memory access (DMA)
357:
109:second-generation computer
29:
27:Supercomputer of the 1960s
1252:Lavington, Simon (1998),
1232:Lavington, Simon (1975),
1214:Lavington, Simon (1980),
1051:Lavington, Simon (2012),
767:History of supercomputing
719:development environment.
277:Royal Radar Establishment
181:National Museums Scotland
143:Atlas Computer Laboratory
44:
1563:Transistorized computers
1343:10.1109/TEC.1962.5219356
1310:10.1049/pi-b-2.1959.0316
741:and program counters; a
424:, who later praised it:
222:University of Manchester
172:), and the other to the
123:University of Manchester
1553:Early British computers
1490:M. R. Williams (1997).
1437:10.1145/1460764.1460786
1216:Early British Computers
550:An associative memory (
366:University of Cambridge
245:central processing unit
230:Atomic Energy Authority
154:University of Cambridge
1463:10.1093/comjnl/5.3.238
1411:10.1093/comjnl/4.3.226
1376:10.1093/comjnl/4.3.222
1109:Hayes, John.P (1978),
810:Hayes, John.P (1978),
569:asynchronous processor
562:Instruction pipelining
556:page address registers
431:
295:which had support for
1583:History of Manchester
411:Ferranti-Packard 6000
360:Titan (1963 computer)
216:Through this period,
176:(AWRE), Aldermaston.
1450:The Computer Journal
1398:The Computer Journal
1363:The Computer Journal
755:Manchester computers
693:high-level languages
619:most significant bit
336:University of London
139:University of London
61:Manchester computers
1521:15 May 2020 at the
1321:. pp. 657–663.
1272:"The PDP-10 Family"
1098:. 19 December 2022.
638:software interrupts
41:
1558:Ferranti computers
845:(1): 13–15. 1964.
609:The uppermost ten
481:(equivalent to 96
293:assembler language
255:Muse becomes Atlas
141:, and one for the
1263:978-1-902505-01-5
1245:978-1-902505-01-5
886:, pp. 30–31.
691:One of the first
541:memory-mapped I/O
354:Titan and Atlas 2
191:in Chilton, near
86:
85:
16:(Redirected from
1595:
1573:48-bit computers
1505:
1486:
1467:
1465:
1440:
1423:
1413:
1388:
1378:
1353:
1351:
1349:
1332:
1322:
1313:
1282:
1276:
1266:
1248:
1228:
1210:
1176:
1175:, pp. 50–52
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1150:
1144:
1143:
1141:
1130:
1124:
1123:
1106:
1100:
1099:
1092:
1086:
1083:Bell et al. 1978
1080:
1074:
1068:
1062:
1061:
1059:
1048:
1042:
1036:
1023:
1017:
1011:
1005:
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993:
982:
976:
967:
961:
955:
949:
938:
937:
936:
934:
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911:
905:
899:
893:
887:
881:
875:
869:
863:
857:
851:
850:
831:
825:
824:
807:
801:
800:, pp. 44–45
795:
789:
783:
761:Atlas Supervisor
735:Backus–Naur form
686:Atlas Supervisor
666:operating system
581:add – 1.59
309:Ferranti Mercury
297:multiprogramming
249:operating system
145:at Chilton near
49:
42:
21:
1603:
1602:
1598:
1597:
1596:
1594:
1593:
1592:
1543:
1542:
1523:Wayback Machine
1512:
1502:
1489:
1483:
1470:
1443:
1426:
1391:
1356:
1347:
1345:
1330:
1325:
1316:
1304:(29): 464–466.
1293:
1290:
1288:Further reading
1285:
1274:
1269:
1264:
1251:
1246:
1231:
1226:
1213:
1189:
1185:
1180:
1179:
1171:
1167:
1162:. January 1965.
1152:
1151:
1147:
1139:
1132:
1131:
1127:
1121:
1113:, p. 375,
1108:
1107:
1103:
1094:
1093:
1089:
1085:, pp. 491.
1081:
1077:
1069:
1065:
1057:
1054:The Atlas Story
1050:
1049:
1045:
1037:
1026:
1018:
1014:
1006:
1002:
994:
985:
977:
970:
962:
958:
950:
941:
932:
930:
929:on 28 July 2012
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828:
822:
809:
808:
804:
796:
792:
784:
780:
775:
751:
682:
603:
519:program counter
508:index registers
506:128 high-speed
444:
439:
407:ICT 1900 series
378:
362:
356:
305:
257:
220:'s team at the
206:
201:
52:
35:
28:
23:
22:
15:
12:
11:
5:
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1511:
1510:External links
1508:
1507:
1506:
1500:
1487:
1481:
1468:
1456:(3): 238–244.
1441:
1424:
1404:(3): 226–229.
1389:
1369:(3): 222–225.
1354:
1337:(2): 223–235.
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1314:
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1262:
1249:
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1173:Lavington 1980
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1075:
1071:Lavington 1975
1063:
1043:
1039:Lavington 1975
1024:
1020:Lavington 1975
1012:
1008:Lavington 1975
1000:
996:Lavington 1975
983:
979:Lavington 1975
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964:Lavington 1975
956:
952:Lavington 1975
939:
912:
908:Lavington 1975
900:
896:Lavington 1975
888:
884:Lavington 1975
876:
872:Lavington 1998
864:
860:Lavington 1998
852:
826:
820:
814:, p. 21,
802:
798:Lavington 1998
790:
786:Lavington 1975
777:
776:
774:
771:
770:
769:
764:
758:
750:
747:
743:context switch
697:Atlas Autocode
681:
678:
674:Ferranti Orion
652:, for example
615:operation code
602:
599:
598:
597:
594:
591:
588:Floating-point
585:
565:
564:
559:
548:
537:
522:
512:floating-point
504:
501:virtual memory
493:
486:
471:
464:
457:
443:
440:
438:
435:
418:C. Gordon Bell
383:floating-point
377:
374:
358:Main article:
355:
352:
313:John Cockcroft
304:
301:
256:
253:
205:
202:
200:
197:
98:virtual memory
94:supercomputers
84:
83:
76:
72:
71:
68:
64:
63:
58:
57:Product family
54:
53:
50:
26:
24:
18:Atlas Computer
14:
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495:96K words of
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933:21 September
931:, retrieved
927:the original
921:
915:
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874:, p. 44
867:
862:, p. 43
855:
842:
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829:
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788:, p. 34
781:
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728:
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717:machine code
701:Tony Brooker
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683:
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583:microseconds
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532:, including
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162:time-sharing
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107:Atlas was a
106:
89:
87:
67:Release date
36:
1060:, p. 7
662:square root
576:Fixed-point
526:peripherals
515:accumulator
348:core memory
265:IBM STRETCH
261:Univac LARC
241:card reader
234:microsecond
218:Tom Kilburn
119:transistors
32:UNIVAC 1101
1547:Categories
773:References
646:procedures
623:subroutine
545:interrupts
536:facilities
497:drum store
479:core store
226:transistor
204:Background
75:Units sold
1420:0010-4620
1385:0010-4620
1208:0958-7403
922:The Atlas
658:logarithm
617:. If the
601:Extracode
477:words of
454:word size
288:compilers
185:Edinburgh
116:germanium
1519:Archived
1202:: 9–18,
847:Archived
749:See also
705:Algol 60
680:Software
650:hardware
579:register
528:such as
442:Hardware
391:CDC 6600
321:ALGOL 60
317:Autocode
236:engine.
137:and the
129:and the
127:Ferranti
113:discrete
111:, using
1348:16 June
709:Fortran
670:program
631:address
629:), its
459:A fast
325:Fortran
199:History
131:Plessey
80:Atlas 2
78:3 (+ 3
1498:
1479:
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1383:
1281:. DEC.
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1242:
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731:macros
660:, and
451:48-bit
437:Design
376:Legacy
193:Oxford
147:Oxford
102:paging
1331:(PDF)
1275:(PDF)
1140:(PDF)
1058:(PDF)
713:COBOL
642:traps
554:) of
461:adder
396:CSIRO
170:AVEVA
158:Titan
90:Atlas
40:Atlas
1496:ISBN
1477:ISBN
1416:ISSN
1381:ISSN
1350:2023
1258:ISBN
1240:ISBN
1220:ISBN
1204:ISSN
1115:ISBN
935:2010
816:ISBN
711:and
654:sine
611:bits
338:and
323:and
263:and
88:The
70:1962
1458:doi
1433:doi
1406:doi
1371:doi
1339:doi
1306:doi
1302:106
640:or
627:ROM
543:),
420:of
273:EMI
183:in
166:CAD
1549::
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1200:62
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1027:^
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483:KB
473:16
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340:BP
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490:K
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475:K
82:)
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