436:
36:
217:-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
272:
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.
335:(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
271:
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
737:
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
374:
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
319:
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
279:
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
197:
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
602:
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
417:
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,
382:
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
375:
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.
369:
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
85:, 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
357:, 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
320:
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.
507:(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
260:(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
712:, 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
221:
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
618:
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
665:
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
198:
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
1584:
199:
168:
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
232:, 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
443:
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):
435:
726:
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
1293:
1574:
1564:
1515:
518:
registers: 125 was supervisor (interrupt) control, 126 was extracode control, and 127 was user control. Register 0 always held value 0.
257:
296:
The first Atlas was built up at the university throughout 1962. The schedule was further constrained by the planned shutdown of the
453:. A word could hold one floating-point number, one instruction, two 24-bit addresses or signed integers, or eight 6-bit characters.
1291:
T. Kilburn; D.B.G. Edwards; D. Aspinall (September 1959). "Parallel addition in digital computers: A new fast 'carry' circuit".
391:
104:
917:
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332:
843:
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The need to support many peripherals and the need to run fast are naturally at odds. A program that processes data from a
153:
operating system developed by Cambridge University Computer Laboratory. Two further Atlas 2s were delivered: one to the
1049:
742:
from user mode to extracode mode or executive mode, or from extracode mode to executive mode, was therefore very fast.
1154:
1559:
1496:
1477:
1220:
1115:
816:
111:
19:
This article is about a British supercomputer. For the early American codebreaking computer also known as Atlas, see
1426:
Proceedings of the December 12–14, 1961, Eastern Joint Computer Conference: Computers - Key to Total Systems Control
422:
In June 2022 an IEEE Milestone was dedicated to the "Atlas Computer and the Invention of Virtual Memory 1957-1962".
390:
Ferranti was having serious financial difficulties in the early 1960s, and decided to sell the computer division to
1549:
1150:
730:. Its variables were in <angle brackets> and it had a text parser, giving SPG program text a resemblance to
489:
words of read-only memory (referred to as the fixed store). This contained the supervisor and extracode routines.
1579:
177:
1131:
410:
308:. It was not until January 1964 that the final version of Supervisor was installed, along with compilers for
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642:
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being determined by the other nine bits. About 250 extracodes were implemented, of the 512 possible.
162:
304:, director of the AEA. This system had only an early version of Supervisor, and the only compiler was for
280:
his Ph.D. in physics at age 22), the team eventually delivered a Supervisor consisting of 35,000 lines of
1554:
548:
97:
300:
machine at the end of December. Atlas met this goal, and was officially commissioned on 7 December by
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361:(Aldermaston) in 1963, and another to the government-sponsored Computer Aided Design Center in 1966.
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169:
131:
1524:
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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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233:
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35:
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http://bitsavers.informatik.uni-stuttgart.de/pdf/ict_icl/atlas/ (Several reference documents)
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552:
399:
348:
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68:
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and introduced the notion of extra codes to extend the functionality of its instruction set.
202:
Advisory Committee on High Speed Calculating Machines, better known as the Brunt Committee.
1314:
F. H. Sumner; G. Haley; E. C. Y. Chen. "The Central Control Unit of the "Atlas" Computer".
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49:
8:
832:"COMPUTERS AND CENTERS, OVERSEAS: 2. Ferranti Ltd., Atlas 2 Computer, London Wl, England"
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The Atlas was highly regarded by many in the computer industry. Among its admirers was
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236:(CPU), the new system would need to have additional memory to buffer data and have an
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1473:
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1236:
1216:
1200:
1111:
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661:. But about half of the codes were designated as Supervisor functions, which invoked
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1302:
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696:, which was contemporary to Algol 60 and created specifically to address what
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666:
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638:
623:
496:(eqv. to 576 KB), split across four drums but integrated with the core store using
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285:
237:
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that embraced supervisor ('sacred') store, V-store, fixed store and the user store
275:
The detailed design was completed by the end of 1959, and the construction of the
1519:
673:, had similar mechanisms for calling on the services of their operating systems.
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could communicate with the Supervisor. Other UK machines of the era, such as the
515:
395:
101:
1356:"The Manchester University Atlas Operating System Part I: Internal Organization"
1324:
831:
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Atlas pioneered many software concepts still in common use today, including the
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and extracode routines, by reading and writing special wired-in store addresses.
739:
693:
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627:
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508:
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1391:"The Manchester University Atlas Operating System Part II: Users' Description"
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1381:
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1355:
1339:
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perceived to be some defects in Algol 60. The Atlas did however support
685:, "considered by many to be the first recognisable modern operating system".
526:
464:
82:
1433:
1323:
Kilburn, T.; Edwards, D. B. G.; Lanigan, M. J.; Sumner, F. H. (April 1962).
713:
697:
150:
1093:"Milestones:Atlas Computer and the Invention of Virtual Memory, 1957-1962"
555:
to determine whether the desired virtual memory location was in core store
323:
Ferranti sold two other Atlas installations, one to a joint consortium of
1139:. London: International Computers and Tabulators Limited. p. 12.1/1.
1133:
I.C.T. Atlas 1 Computer Programming Manual for Atlas Basic Language (ABL)
658:
579:
493:
336:
253:
249:
229:
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20:
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Atlas computer control console from the University of London, about 1964
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in Australia, which had originally been in discussions to buy an Atlas.
619:
522:
394:(ICT) in 1963. ICT decided to focus on the mid-range market with their
214:
107:
1267:
Bell, C. Gordon; Kotok, Alan; Hastings, Thomas; Hill, Richard (1978).
248:
When the Brunt Committee heard of new and much faster US designs, the
1424:
T. Kilburn; R.B. Payne; D.J. Howarth (1962). "The Atlas Supervisor".
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634:
541:
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The Atlas Supervisor paper (T Kilburn, R B Payne, D J Howarth, 1962)
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309:
305:
276:
115:
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In February 1962, Ferranti gave some parts of an Atlas machine to
176:; the main console itself was rediscovered in July 2014 and is at
1294:
Proceedings of the IEE - Part B: Radio and Electronic Engineering
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313:
119:
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techniques; this approach quickly spread, and is now ubiquitous.
1423:
568:— so performance measurements were not easy, but as an example:
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Capability for the addition of (for the time) sophisticated new
1193:
Resurrection: The Bulletin of the Computer Conservation Society
611:
593:
Floating-point multiply, double modify – 4.97 microseconds
564:
Atlas did not use a synchronous clocking mechanism — it was an
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222:
181:
149:, or Atlas 2, it had a different memory organisation and ran a
135:
90:
1313:
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that used novel circuitry to minimise carry propagation time.
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158:
110:. Atlas was created in a joint development effort among the
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1276:
Computer Engineering: A DEC View of Hardware Systems Design
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1031:
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Floating-point add, double modify – 2.61 microseconds
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that could coordinate the flow of data around the system.
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607:
261:
1585:
Department of Computer Science, University of Manchester
1441:
D. J. Howarth; P. D. Jones; M. T. Wyld (November 1962).
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which would have been too inefficient to implement in
89:(at that time referred to as "one-level store") using
1266:
1253:(2 ed.), Swindon: The British Computer Society,
1079:
754: – Series of stored-program electronic computers
463:
24-bit (2 million words, 16 million characters)
398:, a flexible range of machines based on the Canadian
1316:
Information Processing 1962, Proc. IFIP Congress '62
157:Centre in Cambridge (later called CADCentre, then
141:A derivative system was built by Ferranti for the
40:The University of Manchester Atlas in January 1963
1541:
719:Several of the compilers were written using the
200:Department of Scientific and Industrial Research
788:
610:of a 48-bit Atlas machine instruction were the
500:. The page size was 512 words, i.e. 3072 bytes.
482:), featuring interleaving of odd/even addresses
122:. Two other Atlas machines were built: one for
1486:
1470:The First Computers: History and Architectures
1156:The I.C.T. Atlas I Computer Programming Manual
536:Peripheral control through V-store addresses (
256:, they were able to gain the attention of the
587:add, no modification – 1.61 microseconds
288:to solve the problem of peripheral handling.
1535:Ferranti Atlas 1 & 2: List of References
776:
641:today. They were used to call mathematical
922:, University of Manchester, archived from
723:, considered to be the first of its type.
34:
1458:
1406:
1371:
1248:
1235:, Swindon: The British Computer Society,
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868:
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264:, and design teams at Manchester and the
258:National Research Development Corporation
1332:IRE Transactions on Electronic Computers
434:
1575:Collection of National Museums Scotland
1468:Raúl Rojas; Ulf Hashagen, eds. (2000).
1388:
1353:
1186:
1151:"12. Further Facilities and Techniques"
721:Brooker Morris Compiler Compiler (BMCC)
622:jump to a location in the fixed store (
378:It was not until 1964's arrival of the
1565:Computer-related introductions in 1962
1542:
1129:
1108:Computer Architecture and Organization
809:Computer Architecture and Organization
392:International Computers and Tabulators
1105:
806:
633:Extracodes were what would be called
359:Atomic Weapons Research Establishment
243:
163:Atomic Weapons Research Establishment
342:
333:Atomic Energy Research Establishment
1513:The Atlas Autocode Reference Manual
13:
1284:
514:. Three of the 128 registers were
14:
1596:
1506:
1489:A History of Computing Technology
1251:A History of Manchester Computers
1232:A History of Manchester Computers
846:from the original on 3 June 2018.
1130:Cronin, D.E. (31 January 1965).
291:
1491:. IEEE Computer Society Press.
1428:. Macmillan. pp. 279–294.
1389:Howarth, D. J. (1 March 1961).
1215:, Manchester University Press,
1179:
1163:
1143:
1123:
1099:
1085:
1041:
910:
1189:"Designing and Building Atlas"
824:
800:
760: – First operating system
178:Rutherford Appleton Laboratory
1:
1443:"The Atlas Scheduling System"
769:
692:available on Atlas was named
411:Digital Equipment Corporation
192:
81:was one of the world's first
1354:Kilburn, T. (1 March 1961).
1187:Edwards, Dai (Summer 2013),
603:faster than the core store.
597:
331:in 1963, and another to the
213:had been experimenting with
7:
836:Digital Computer Newsletter
745:
676:
430:
10:
1601:
1325:"One-Level Storage System"
549:content-addressable memory
531:direct memory access (DMA)
346:
187:
98:second-generation computer
18:
16:Supercomputer of the 1960s
1249:Lavington, Simon (1998),
1229:Lavington, Simon (1975),
1211:Lavington, Simon (1980),
1048:Lavington, Simon (2012),
764:History of supercomputing
716:development environment.
425:
364:
266:Royal Radar Establishment
170:National Museums Scotland
132:Atlas Computer Laboratory
63:
55:
45:
33:
1560:Transistorized computers
1340:10.1109/TEC.1962.5219356
1307:10.1049/pi-b-2.1959.0316
738:and program counters; a
413:, who later praised it:
211:University of Manchester
161:), and the other to the
112:University of Manchester
1550:Early British computers
1487:M. R. Williams (1997).
1434:10.1145/1460764.1460786
1213:Early British Computers
547:An associative memory (
355:University of Cambridge
234:central processing unit
219:Atomic Energy Authority
143:University of Cambridge
1460:10.1093/comjnl/5.3.238
1408:10.1093/comjnl/4.3.226
1373:10.1093/comjnl/4.3.222
1106:Hayes, John.P (1978),
807:Hayes, John.P (1978),
566:asynchronous processor
559:Instruction pipelining
553:page address registers
440:
420:
284:which had support for
1580:History of Manchester
438:
415:
400:Ferranti-Packard 6000
349:Titan (1963 computer)
205:Through this period,
165:(AWRE), Aldermaston.
1447:The Computer Journal
1395:The Computer Journal
1360:The Computer Journal
752:Manchester computers
690:high-level languages
616:most significant bit
325:University of London
128:University of London
50:Manchester computers
1518:15 May 2020 at the
1318:. pp. 657–663.
1269:"The PDP-10 Family"
1095:. 19 December 2022.
635:software interrupts
30:
1555:Ferranti computers
842:(1): 13–15. 1964.
606:The uppermost ten
478:(equivalent to 96
441:
282:assembler language
244:Muse becomes Atlas
130:, and one for the
28:
1260:978-1-902505-01-5
1242:978-1-902505-01-5
883:, pp. 30–31.
688:One of the first
538:memory-mapped I/O
343:Titan and Atlas 2
180:in Chilton, near
75:
74:
1592:
1570:48-bit computers
1502:
1483:
1464:
1462:
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1420:
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1346:
1329:
1319:
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1279:
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1173:
1172:, pp. 50–52
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1147:
1141:
1140:
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1103:
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1080:Bell et al. 1978
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1071:
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847:
828:
822:
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804:
798:
797:, pp. 44–45
792:
786:
780:
758:Atlas Supervisor
732:Backus–Naur form
683:Atlas Supervisor
663:operating system
578:add – 1.59
298:Ferranti Mercury
286:multiprogramming
238:operating system
134:at Chilton near
38:
31:
27:
1600:
1599:
1595:
1594:
1593:
1591:
1590:
1589:
1540:
1539:
1520:Wayback Machine
1509:
1499:
1480:
1344:
1342:
1327:
1301:(29): 464–466.
1287:
1285:Further reading
1282:
1271:
1261:
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1223:
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1177:
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1159:. January 1965.
1149:
1148:
1144:
1136:
1128:
1124:
1118:
1110:, p. 375,
1104:
1100:
1091:
1090:
1086:
1082:, pp. 491.
1078:
1074:
1066:
1062:
1054:
1051:The Atlas Story
1046:
1042:
1034:
1023:
1015:
1011:
1003:
999:
991:
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959:
955:
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926:on 28 July 2012
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679:
600:
516:program counter
505:index registers
503:128 high-speed
433:
428:
396:ICT 1900 series
367:
351:
345:
294:
246:
209:'s team at the
195:
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41:
24:
17:
12:
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5:
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1522:
1508:
1507:External links
1505:
1504:
1503:
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1478:
1465:
1453:(3): 238–244.
1438:
1421:
1401:(3): 226–229.
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1366:(3): 222–225.
1351:
1334:(2): 223–235.
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1170:Lavington 1980
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1068:Lavington 1975
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1036:Lavington 1975
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1017:Lavington 1975
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1005:Lavington 1975
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993:Lavington 1975
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961:Lavington 1975
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949:Lavington 1975
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905:Lavington 1975
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893:Lavington 1975
885:
881:Lavington 1975
873:
869:Lavington 1998
861:
857:Lavington 1998
849:
823:
817:
811:, p. 21,
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795:Lavington 1998
787:
783:Lavington 1975
774:
773:
771:
768:
767:
766:
761:
755:
747:
744:
740:context switch
694:Atlas Autocode
678:
675:
671:Ferranti Orion
649:, for example
612:operation code
599:
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595:
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591:
588:
585:Floating-point
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509:floating-point
501:
498:virtual memory
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407:C. Gordon Bell
372:floating-point
366:
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347:Main article:
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930:21 September
928:, retrieved
924:the original
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876:
871:, p. 44
864:
859:, p. 43
852:
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785:, p. 34
778:
736:
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714:machine code
698:Tony Brooker
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580:microseconds
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529:, including
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96:Atlas was a
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78:
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56:Release date
25:
1057:, p. 7
659:square root
573:Fixed-point
523:peripherals
512:accumulator
337:core memory
254:IBM STRETCH
250:Univac LARC
230:card reader
223:microsecond
207:Tom Kilburn
108:transistors
21:UNIVAC 1101
1544:Categories
770:References
643:procedures
620:subroutine
542:interrupts
533:facilities
494:drum store
476:core store
215:transistor
193:Background
64:Units sold
1417:0010-4620
1382:0010-4620
1205:0958-7403
919:The Atlas
655:logarithm
614:. If the
598:Extracode
474:words of
451:word size
277:compilers
174:Edinburgh
105:germanium
1516:Archived
1199:: 9–18,
844:Archived
746:See also
702:Algol 60
677:Software
647:hardware
576:register
525:such as
431:Hardware
380:CDC 6600
310:ALGOL 60
306:Autocode
225:engine.
126:and the
116:Ferranti
102:discrete
100:, using
1345:16 June
706:Fortran
667:program
628:address
626:), its
456:A fast
314:Fortran
188:History
120:Plessey
69:Atlas 2
67:3 (+ 3
1495:
1476:
1415:
1380:
1278:. DEC.
1257:
1239:
1219:
1203:
1114:
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728:macros
657:, and
448:48-bit
426:Design
365:Legacy
182:Oxford
136:Oxford
91:paging
1328:(PDF)
1272:(PDF)
1137:(PDF)
1055:(PDF)
710:COBOL
639:traps
551:) of
458:adder
385:CSIRO
159:AVEVA
147:Titan
79:Atlas
29:Atlas
1493:ISBN
1474:ISBN
1413:ISSN
1378:ISSN
1347:2023
1255:ISBN
1237:ISBN
1217:ISBN
1201:ISSN
1112:ISBN
932:2010
813:ISBN
708:and
651:sine
608:bits
327:and
312:and
252:and
118:and
77:The
59:1962
1455:doi
1430:doi
1403:doi
1368:doi
1336:doi
1303:doi
1299:106
637:or
624:ROM
540:),
409:of
262:EMI
172:in
155:CAD
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1393:.
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1024:^
983:^
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480:KB
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402:.
329:BP
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1305::
487:K
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23:.
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