22:
293:
drivers for SCSI (APEs) and serial boards (ACEs). The processing boards are interconnected by a redundant low latency parallel bus (ABUS) running at 20 MB/s. The UNIX kernels running on the adjunct processors are modified to allow the fork/exec of processes across processing units. The system calls and peripheral drivers are also extended to allow processes to access remote resources across the ABUS. Since the ABUS is hot-swappable, processors can be added or replaced without shutting down the system. If one of the adjunct processors fails during operation, the system can detect and restart programs that were running on the failed element.
940:
310:
323:
331:
178:
There were improvements to the 3B20D UNIX-RTR system in both software and hardware in the 1980s, 1990s, 2000s, and 2010s. Innovations included disk independent operation (DIOP: the ability to continue essential software processing such as telecommunications after duplex failure of redundant essential
167:
general-purpose computer in the commercial market in 1984. The 3B20E was created to provide a cost-reduced 3B20D for small offices that did not expect such high availability. It consists of a virtual "emulated" 3B20D environment running on a stand-alone general purpose computer; the system was ported
397:
The 3B2/500 was the next model to appear, essentially a 3B2/600 with enough components removed to fit into a 400 case; one internal disk drive and several backplane slots are sacrificed in this conversion. Unlike the 600, which because of its two large fans is loud, the 500 is tolerable in an office
389:
controller for the 60 MB QIC tape and two internal full-height disk drives. The 600 is approximately twice as tall as a 400, and is oriented with the tape and floppy disk drives opposite the backplane (instead of at a right angle to it as on the 3xx, 4xx and later 500 models). Early models use an
292:
Indian Hill West facility by the High
Performance Computer Development Lab, the system consists of multiple high performance (at the time) processor boards – adjunct processing elements (APEs) and adjunct communication elements (ACEs). These adjunct processors run a customized UNIX kernel with
287:
server introduced in 1987 and based on a 'snugly-coupled' architecture using the WE series 32x00 32-bit processor. Known internally as 'Apache', the 3B4000 is a follow-on to the 3B15 and initial revisions use a 3B15 as a master processor. Developed in the mid-1980's at the
152:. The first 3B20D is called the Model 1. Each processor's control unit consists of two frames of circuit packs. The whole duplex system requires seven-foot frames of circuit packs plus at least one tape drive frame (most telephone companies at that time wrote billing data on
258:
32-bit microprocessor. The initial versions have discrete memory management unit hardware using gate arrays, and support segment-based memory translation. I/O is programmed using memory-mapped techniques. The machine is approximately the size of a
296:
The 3B4000 is capable of significant expansion; one test system (including storage) occupies 17 mid-height cabinets. Generally, the performance of the system increases linearly with additional processing elements, however the lack of a true
353:
The 300 was soon supplanted by the 3B2/310 running at 10 MHz, which features the WE 32100 CPU as do later models. The Model 400, introduced in 1985, allows more peripheral slots and more memory, and has a built-in 23 MB
179:
disks); off-line boot (the ability to split in half and boot the out-of-service half, typically on a new software release) and switch forward (switch processing to the previously out-of-service half); upgrading the disks to
160:-sized disk drives. For training and lab purposes, a 3B20D can be divided into two "half-duplex" systems. A 3B20S consists of most of the same hardware as a half-duplex but uses a completely different operating system.
79:
In 1984, after regulatory constraints were lifted, AT&T introduced the 3B20D, 3B20S, 3B5, and 3B2 to the general computer market, a move that some commentators saw as an attempt to compete with
401:
The 3B2/700 is an uprated version of the 600 featuring a slightly faster processor (WE 32200 at 22 MHz), and the 3B2/1000 is an additional step in this direction (WE 32200 at 24 MHz).
350:. The 3B2 Model 300, which can support up to 18 users, is approximately 4 inches (100 mm) high and the 3B2 Model 400 is approximately 8 inches (200 mm) high.
87:, in which AT&T had a minority shareholding. After AT&T bought NCR Corporation, effective January 1992, the computers were marketed through NCR sales channels.
90:
Having produced 70,000 units, the AT&T Oklahoma City plant stopped manufacturing 3B machines at the end of 1993, with the 3B20D to be the last units manufactured.
641:
619:
242:, which was built to replace the man-based messaging system of earlier Olympiads. The system connected around 1800 user terminals and 200 printers. The
632:
J. O. Becker, The 3B20D PROCESSOR and DMERT Operating System (The Bell System
Technical Journal, January 1983, Vol. 62, No. 1, Part 1), Page 193
45:
operating system. The line primarily consists of the models 3B20, 3B5, 3B15, 3B2, and 3B4000. The series is notable for controlling a series of
831:
144:(Real Time Reliable) in 1982. The Data Manipulation Unit (DMU) provides arithmetic and logic operations on 32-bit words using eight
526:
226:
use. The 3B20S has hardware similar to the 3B20D, but one unit instead of two. The machine is approximately the size of a large
737:
503:
195:
868:
567:
72:
The general purpose family of 3B computer systems includes the 3B2, 3B5, 3B15, 3B20S, and 3B4000. They run the AT&T
275:
The 3B15, introduced in 1985, uses the WE 32100 and is the faster follow-on to the 3B5 with similar large form factor.
246:
is an enhanced version of the 3B20S, adding in a second processing unit working in parallel as a multiprocessor unit.
896:
126:
301:
capability requires rewriting applications that rely heavily on this feature to avoid a severe performance penalty.
21:
824:
190:
The processor was re-engineered and renamed in 1992 as the 3B21D. It is still in use as of 2023 as a component of
347:
717:
439:, is tailored for use as a productivity tool in office environments and as an electronic communication center.
53:, for general computing purposes, and for serving as the historical software porting base for commercial UNIX.
480:
363:
589:
883:
817:
46:
698:
968:
797:
172:
114:
385:
The 3B2/600, running at 18 MHz, offers an improvement in performance and capacity: it features a
978:
394:
card to interface the SCSI controller with ESDI disks, with later models using SCSI drives directly.
106:
34:
963:
432:
973:
448:
359:
355:
901:
264:
198:
149:
130:
231:
8:
202:
98:
The original series of 3B computers includes the models 3B20C, 3B20D, 3B21D, and 3B21E.
76:
operating system and were named after the successful 3B20D High
Availability processor.
742:
722:
676:
531:
508:
485:
84:
62:
944:
284:
180:
110:
50:
680:
263:, though adding the reel-to-reel tape drive increases its size. These computers use
668:
416:
169:
118:
38:
858:
850:
411:
309:
289:
164:
157:
122:
779:
65:
at
Pacific Bell. Within two years, several hundred were in place throughout the
654:
428:
342:
32-bit microprocessor at 8 MHz with memory management chips that supports
153:
791:
957:
659:
343:
298:
201:
and the 4ESS and 5ESS switches, which Nokia inherited from AT&T spin-off
672:
863:
230:, requiring a minimum of 170 square feet floor space. It was in use at the
227:
184:
809:
916:
891:
424:
223:
66:
906:
873:
339:
260:
255:
145:
322:
222:
and produced by
Western Electric in 1982 for general purpose internal
163:
The 3B20C was briefly available as a high-availability fault tolerant
926:
219:
102:
803:
33:
are a line of minicomputers made between the late 1970s and 1993 by
548:
431:
microprocessor. It runs a derivative of Unix System V Release 2 by
141:
785:
911:
620:"AT&T Makes Last 3B2 City-Produced Computer Stuff of Legends"
391:
362:(nicknamed the "floppy tape"). These three models use standard
83:. In Europe, the 3B computers were distributed by Italian firm
427:
is unrelated in hardware to the 3B line, and is based on the
235:
191:
137:
921:
840:
583:
581:
386:
73:
42:
330:
80:
578:
69:. Some of the units came with "small, slow hard disks".
498:
496:
546:
Walter Zintz (July 1984). "The Unix
Connection: 3B2".
493:
474:
472:
470:
468:
466:
464:
382:
There are also Model 100 and Model 200 3B2 systems.
125:, for telecommunications applications including the
117:. They were first produced in the late 1970s at the
655:"Olympics electronic messaging system demonstrated"
692:
690:
521:
519:
93:
461:
254:The 3B5 is built with the older Western Electric
136:They use the Duplex Multi Environment Real Time (
955:
687:
516:
478:
825:
168:to many computers, but primarily runs on the
642:3B20S Processor System Index and Description
545:
183:(SSD) ; and upgrading the tape unit to
839:
715:
613:
611:
832:
818:
590:"Olivetti: Biting the Hand that Feeds It?"
404:
565:
435:. The system, which is also known as the
338:The 3B2 was introduced in 1984 using the
696:
608:
329:
321:
308:
20:
738:"A.T.&T. Displays Midsize Computer"
568:"AT&T introduces new computer line"
539:
504:"A.T.&T. Addition To Computer Line"
234:, where around twelve 3B20S served the
41:subsidiary, for use with the company's
956:
758:
756:
617:
813:
762:AT&T, Select Code 999-601-311IS,
587:
334:WE 321SB VMEbus Single Board Computer
218:The 3B20S (simplex) was developed at
140:) operating system which was renamed
718:"Computers Introduced At A.T.&T"
561:
559:
527:"Digital Introduces Computer Series"
753:
13:
644:, Western Electric Co., July 1981.
14:
990:
786:AT&T 3B2/3B5 Computer Systems
773:
716:Calvin Sims (September 3, 1987).
697:Chandler, David (December 1985).
618:Denton, Jon (December 16, 1993).
566:Mankowski, Cal (March 27, 1984).
556:
479:Andrew Pollack (March 28, 1984).
419:in 1985 that is often dubbed the
304:
61:The first 3B20D was installed in
16:AT&T/Bell family of computers
938:
793:AT&T 3B2 400 Computer Review
588:Faden, Michael (February 1988).
208:
764:AT&T UNIX PC Owner's Manual
730:
709:
647:
481:"AT&T Offers Its Computers"
348:Switching Control Center System
94:3B high-availability processors
635:
626:
1:
917:Stromberg-Carlson/Siemens DCO
604:– via Internet Archive.
454:
927:Automatic Electric GTD-5 EAX
884:Electronic switching systems
748:could support up to 80 users
596:. pp. 14, 16, 20, 22–23
47:electronic switching systems
7:
892:Western Electric 1ESS/1AESS
442:
398:environment, like the 400.
240:Electronic Messaging System
25:A 3B15 computer, circa 1997
10:
995:
667:(11): 113. November 1983.
115:real-time operating system
113:processor units running a
56:
935:
882:
848:
278:
101:These systems are 32-bit
35:AT&T Computer Systems
912:Northern Telecom DMS-100
415:, AT&T introduced a
358:tape drive managed by a
213:
673:10.1109/MC.1983.1654251
433:Convergent Technologies
405:3B1 desktop workstation
270:
849:Early automatic &
800:by TanRu Nomad in 2012
449:Altos Computer Systems
360:floppy disk controller
335:
327:
317:
314:
249:
26:
945:Telephones portal
907:Northern Electric SP1
902:Western Electric 5ESS
897:Western Electric 4ESS
782:at Harte Technologies
409:Officially named the
333:
325:
312:
199:signal transfer point
194:products such as the
24:
874:Western Electric 5XB
869:Western Electric 1XB
699:"The Monthly Report"
379:" hard disk drives.
238:requirements of the
232:1984 Summer Olympics
806:by Seth J. Morabito
346:. Uses include the
326:3B2/300 motherboard
203:Lucent Technologies
31:3B series computers
969:AT&T computers
843:telephone switches
743:The New York Times
723:The New York Times
532:The New York Times
509:The New York Times
486:The New York Times
336:
328:
315:
63:Fresno, California
27:
951:
950:
851:crossbar switches
535:. March 25, 1987.
512:. March 16, 1989.
285:high availability
181:solid-state drive
111:high availability
51:telecommunication
986:
979:32-bit computers
943:
942:
941:
834:
827:
820:
811:
810:
794:
767:
760:
751:
750:
746:. May 10, 1988.
734:
728:
727:
713:
707:
706:
694:
685:
684:
651:
645:
639:
633:
630:
624:
623:
622:. The Oklahoman.
615:
606:
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576:
575:
563:
554:
553:
543:
537:
536:
523:
514:
513:
500:
491:
490:
476:
423:. However, this
417:desktop computer
412:AT&T UNIX PC
378:
377:
373:
370:
283:The 3B4000 is a
170:Sun Microsystems
119:Western Electric
39:Western Electric
994:
993:
989:
988:
987:
985:
984:
983:
954:
953:
952:
947:
939:
937:
931:
878:
859:Strowger Switch
844:
838:
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735:
731:
714:
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695:
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407:
375:
371:
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320:
313:A 3B2 model 400
307:
281:
273:
252:
216:
211:
165:multiprocessing
158:washing machine
123:Lisle, Illinois
103:microprogrammed
96:
59:
17:
12:
11:
5:
992:
982:
981:
976:
971:
966:
964:Alcatel-Lucent
949:
948:
936:
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930:
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904:
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837:
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808:
807:
801:
789:
788:at Unixwiz.net
783:
775:
774:External links
772:
769:
768:
752:
729:
708:
686:
646:
634:
625:
607:
577:
555:
552:. p. 142.
538:
515:
492:
459:
458:
456:
453:
452:
451:
444:
441:
429:Motorola 68010
406:
403:
319:
316:
306:
305:Microcomputers
303:
280:
277:
272:
269:
251:
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215:
212:
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207:
154:magnetic tapes
95:
92:
58:
55:
15:
9:
6:
4:
3:
2:
991:
980:
977:
975:
974:Minicomputers
972:
970:
967:
965:
962:
961:
959:
946:
934:
928:
925:
923:
920:
918:
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660:IEEE Computer
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344:demand paging
341:
332:
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311:
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299:shared memory
294:
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276:
268:
267:hard drives.
266:
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245:
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229:
225:
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209:Minicomputers
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204:
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176:
175:environment.
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54:
52:
48:
44:
40:
36:
32:
23:
19:
922:Siemens EWSD
864:Panel Switch
804:3B2 Emulator
763:
747:
741:
732:
721:
711:
705:. p. 8.
702:
664:
658:
649:
637:
628:
598:. Retrieved
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295:
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253:
243:
239:
228:refrigerator
217:
189:
185:CompactFlash
177:
162:
156:), and many
148:4-bit-slice
135:
100:
97:
89:
78:
71:
60:
30:
28:
18:
780:3B2 manuals
703:Unix Review
594:UNIX Review
425:workstation
224:Bell System
121:factory in
67:Bell System
958:Categories
600:August 17,
455:References
261:dishwasher
390:internal
220:Bell Labs
133:systems.
107:redundant
681:47105018
549:HARDCOPY
443:See also
340:WE 32000
256:WE 32000
146:AMD 2901
142:UNIX-RTR
105:duplex (
85:Olivetti
798:YouTube
437:PC-7300
374:⁄
173:Solaris
57:History
766:(1986)
679:
392:Emulex
279:3B4000
677:S2CID
290:Lisle
244:3B20A
236:email
214:3B20S
192:Nokia
138:DMERT
841:NANP
602:2022
387:SCSI
271:3B15
196:2STP
150:ALUs
131:5ESS
129:and
127:4ESS
74:UNIX
49:for
43:UNIX
29:The
796:on
669:doi
572:UPI
421:3B1
364:MFM
356:QIC
318:3B2
265:SMD
250:3B5
81:IBM
960::
755:^
740:.
720:.
701:.
689:^
675:.
665:16
663:.
657:.
610:^
592:.
580:^
570:.
558:^
529:.
518:^
506:.
495:^
483:.
463:^
205:.
187:.
109:)
37:'
833:e
826:t
819:v
726:.
683:.
671::
574:.
489:.
376:4
372:1
369:+
367:5
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
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