580:
249:
595:
456:
338:
750:
320:
571:
speeds of over 33 MHz. Many peripherals and even the bus itself will exhibit undefined behaviors at higher speeds on a large number of motherboards. This is reflected by Intel and AMD processors operating at 50 MHz where their sales show a similar trait of being less popular. Users could potentially negate this by increasing latency for the memory, cache and bus but this would also cause performance to drop.
27:
301:
316:-based code. The processor did, however, sport a 2KB Write-back cache and a special "Write-Burst" signal which offered a slight performance boost in certain applications provided the motherboard was capable of utilizing the feature. The processors were labelled "FasCache" to emphasize this feature as most processors used slower write-through caches.
793:
range. This was essentially a Cyrix Cx486, chipset, graphics and most I/O integrated into a single chip. The CPU performs identically to a Cyrix part at the same clock speed. The STPC was produced until 2008 and was found in a variety of systems, usually small embedded systems for industrial use or
570:
Despite the faster clock speeds, the 50 MHz version of this processor was less popular than the other models Cyrix had produced. This is likely due to VESA Local Bus being common in computers around the time of the processors introduction as the bus was notoriously unreliable when operating at
777:
In 1993, Intel alleged that Cyrix had infringed several patents and initiated legal action. The courts found that Cyrix had indeed reverse engineered the Intel part, but had conceived their own compatible design, the courts also found that Texas
Instruments, SGS-Thomson and IBM were licensed to
448:
Codenamed M6, the Cyrix Cx486DX is essentially the same as the Cx486S except it featured an internal
Floating Point Unit and quadruple the amount of cache memory. It was available in a form that allowed lower voltage operation. The processor was found to have comparable performance to competing
768:
The final version of the Cx486 to bear the Cyrix name was a Clock
Tripling CPU which was only available with a 100 MHz Internal Clock. Introduced in September 1995, it was otherwise not vastly different to the older designs and proved to be competitive both performance-wise and price-wise
802:
form factor. One notable difference between the STPC and other Cx486 processors is the Host Clock which operates at 66 MHz for STPC devices. As such, the 66 MHz model does not use clock doubling at all, but the 133 MHz version does. This differs from most competing systems, such as the
279:
As a result, there were many versions of the Cx486 and the manufacture of them differed slightly depending on which company had built them, though equivalent chips generally perform near-identically enough that the end user would not notice any difference between them.
283:
The contract with SGS-Thomson outlived the Cyrix Cx486 processor's lifespan in the mainstream market by over a decade with SGS-Thomson still producing industrial solutions built upon the Cyrix design into the late-2000s.
757:
The 50 MHz version is again the least common, this time likely due to the slower bus speed rendering any upgrade questionable as the performance gains would be reduced by the lower bus speed.
312:
and like the Intel part, did not have a floating point unit onboard which was of little concern to an average user at the time due to most games and applications using purely
276:
to manufacture their processors, though this was done under a contract that allowed each company to build and sell Cyrix-designed processors under their own branding.
932:
VLB has however had its own share of problems. In particular, VLB video cards may cause reliability problems in motherboards running at 40 or 50 MHz.
1066:
1006:
587:
Introduced in
September 1993 alongside the single clock version was a clock doubling version of the Cx486DX. It was intended to compete with the
778:
produce Intel designs. Eventually the case was dropped and Intel paid Cyrix $ 12 million to drop anti-trust charges against them.
944:
919:
1061:
292:
The Cyrix Cx486 was available with different features, clock speeds and voltages over the duration of its production.
327:
Users could upgrade the processor to 486DX specifications through use of an accessory, the Cyrix Cx487S which was an
904:
591:
and had similar capabilities. Its lower price point than equivalent Intel processors made it a popular choice.
1025:"STPC ATLAS DATASHEET / X86 PC COMPATIBLE INFORMATION APPLIANCE SYSTEM-ON-CHIP - SGS Thomson Microelectronics"
832:
252:
A Cyrix-designed SGS-Thomson processor. SGS sold Cyrix processors under their own label as per their contract.
781:
The legal battle delayed several of Cyrix's products, causing them to arrive later than competing solutions.
257:
228:
with which it was software compatible, would operate in the same motherboards provided proper support by the
889:
127:
978:
851:
1024:
1010:
232:
was available and generally showed comparable performance. The chip also competed with parts from
1038:
72:
308:
Introduced in May 1993, the Cyrix Cx486S, codenamed M5, was designed to be compatible with the
993:"International Business Machines Corporation, Plaintiff-Appellee, v. INTEL CORPORATION (1996)"
992:
795:
331:
Floating Point Unit coprocessor which fit between the CPU and the socket on the motherboard.
273:
148:
8:
769:
against offerings from AMD and Intel though it was later to market than its competitors.
265:
856:
261:
948:
579:
927:
789:
The Cyrix Cx486DX2 design was used by STMicroelectronics in 1999 for their STPC
790:
588:
433:
323:
The Cyrix Cx487S FPU coprocessor, installed between CPU and motherboard socket.
217:
203:
199:
176:
172:
85:
1055:
309:
237:
436:
is a derivative of this processor and was used to upgrade computers on the
248:
963:
871:
594:
804:
703:
Available with permanently attached heatsink, Low
Voltage. QFP Package.
455:
190:
186:
75:
225:
102:
337:
749:
319:
198:
For similarly named Cyrix chips competing with the Intel 386, see
334:
The table below lists the models of this CPU that were produced.
313:
26:
812:
799:
300:
132:
808:
452:
The table below lists models of this CPU that were produced.
437:
233:
221:
136:
56:
743:
Low
Voltage. Available with permanently attached heatsink.
683:
Low
Voltage. Available with permanently attached heatsink.
229:
304:
A Cyrix Cx486S processor. Compatible with the Intel 486SX.
31:
A Cyrix Cx486DX4 microprocessor rated for 100MHz operation
760:
The 80 MHz version was introduced in
November 1994.
328:
269:
214:
564:
Available with permanently attached heatsink. Uncommon.
449:
solutions, but it varied depending on the application.
524:
QFP Package, Low
Voltage. Does not have a heatsink.
1039:"AMD ÉlanTMSC520 Microcontroller Technical Details"
815:which still relied upon a 33 MHz external clock.
1053:
968:- page talking about Cyrix processors in general
894:- page with most Cx486S models and their specs
849:
723:Available with permanently attached heatsink.
663:Available with permanently attached heatsink.
643:Available with permanently attached heatsink.
544:Available with permanently attached heatsink.
426:Available with permanently attached heatsink.
406:Available with permanently attached heatsink.
852:"Texas Instruments to Sell Its Own 486 Chip"
753:Die shot of Texas Instruments TI486DX2-G66.
583:Cyrix Cx486DX2 rated for 66MHz operation.
979:"Intel VS the world - '338 patent cases"
748:
593:
578:
454:
336:
318:
299:
247:
1067:Computer-related introductions in 1993
1054:
16:486-compatible microprocessor by Cyrix
784:
1007:"PIA-647 - An SBC based on the STPC"
953:- page with most models of Cx486DX2
807:processors based on AMD's Enhanced
13:
14:
1078:
872:"Tiger Star System User's Manual"
798:devices, such as those using the
224:. It primarily competed with the
772:
25:
1031:
1017:
999:
985:
850:Jonathan Weber (May 14, 1992).
114:Architecture and classification
971:
956:
937:
912:
897:
882:
864:
843:
825:
1:
879:- a system using the STPC SoC
818:
243:
7:
763:
601:
574:
462:
344:
287:
80:25 MHz to 100 MHz
10:
1083:
504:Does not have a heatsink.
443:
386:Does not have a heatsink.
197:
91:25 MHz to 33 MHz
1062:Cyrix x86 microprocessors
598:Die shot of Cx486DX2-V66.
295:
182:
168:
163:
147:
142:
126:
118:
113:
100:
95:
84:
70:
65:
49:
41:
36:
24:
459:Die shot of Cx486DX-40.
143:Physical specifications
754:
599:
584:
460:
342:
341:Die shot of Cx486S-33.
324:
305:
253:
796:Single-board computer
752:
597:
582:
458:
340:
322:
303:
256:Due to Cyrix being a
251:
811:core as used in the
740:3.45 or 4.0 Volts DC
680:3.3 or 3.45 Volts DC
272:which had their own
260:company, Cyrix used
128:Instruction set
981:. 6 September 2012.
604:
603:Models of Cx486DX2
465:
347:
50:Common manufacturer
37:General information
21:
909:- page with Cx487S
785:Embedded solutions
755:
688:Cx486DX2-V66 PQFP
602:
600:
585:
464:Models of Cx486DX
463:
461:
345:
343:
325:
306:
254:
19:
857:Los Angeles Times
837:CPU-Collection.de
747:
746:
568:
567:
430:
429:
346:Models of Cx486S
262:Texas Instruments
196:
195:
109:8 KB (DX/DX2/DX4)
1074:
1046:
1045:
1043:
1035:
1029:
1028:
1021:
1015:
1014:
1009:. Archived from
1003:
997:
996:
989:
983:
982:
975:
969:
967:
960:
954:
952:
947:. Archived from
941:
935:
934:
926:. Archived from
920:"VESA Local Bus"
916:
910:
908:
901:
895:
893:
886:
880:
878:
876:
868:
862:
861:
847:
841:
840:
829:
614:Clock Frequency
605:
475:Clock Frequency
466:
357:Clock Frequency
348:
29:
22:
18:
1082:
1081:
1077:
1076:
1075:
1073:
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991:
990:
986:
977:
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962:
961:
957:
943:
942:
938:
930:on 2019-02-07.
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32:
17:
12:
11:
5:
1080:
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1069:
1064:
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1047:
1030:
1016:
1013:on 2014-11-07.
998:
984:
970:
955:
951:on 2016-10-24.
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608:Model/Feature
589:Intel 80486DX2
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469:Model/Feature
445:
442:
434:Cyrix Cx486DLC
428:
427:
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408:
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401:
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351:Model/Feature
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245:
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218:microprocessor
204:Cyrix Cx486DLC
200:Cyrix Cx486SLC
194:
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184:
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177:Cyrix Cx486DLC
173:Cyrix Cx486SLC
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34:
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15:
9:
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4:
3:
2:
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792:
782:
779:
773:Legal dispute
770:
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751:
742:
739:
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728:Cx486DX2-V80
727:
726:
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710:
707:
706:
702:
699:
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686:
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668:Cx486DX2-V66
667:
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527:
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520:
517:
514:
511:
509:Cx486DX-33QP
508:
507:
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487:
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477:
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471:
468:
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134:
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99:
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69:
64:
58:
55:
54:
52:
48:
44:
40:
35:
28:
23:
1033:
1019:
1011:the original
1001:
987:
973:
964:"Cyrix CPUs"
958:
949:the original
939:
931:
928:the original
924:The PC Guide
923:
914:
899:
884:
866:
855:
845:
836:
827:
788:
780:
776:
767:
759:
756:
708:Cx486DX2-80
700:3.3 Volts DC
648:Cx486DX2-66
628:Cx486DX2-50
586:
569:
521:3.3 Volts DC
451:
447:
431:
333:
326:
307:
291:
282:
278:
255:
220:designed by
210:
208:
169:Predecessors
734:80 MHz
731:40 MHz
714:80 MHz
711:40 MHz
694:66 MHz
691:33 MHz
674:66 MHz
671:33 MHz
654:66 MHz
651:33 MHz
634:50 MHz
631:25 MHz
555:50 MHz
552:50 MHz
549:Cx486DX-50
535:40 MHz
532:40 MHz
529:Cx486DX-40
515:33 MHz
512:33 MHz
495:33 MHz
492:33 MHz
489:Cx486DX-33
417:40 MHz
414:40 MHz
397:33 MHz
394:33 MHz
377:25 MHz
374:25 MHz
310:Intel 486SX
266:SGS Thomson
211:Cyrix Cx486
119:Application
66:Performance
20:Cyrix Cx486
1056:Categories
833:"Cx486 DX"
819:References
720:5 Volts DC
660:5 Volts DC
640:5 Volts DC
611:Bus Speed
561:5 Volts DC
541:5 Volts DC
501:5 Volts DC
472:Bus Speed
440:platform.
423:5 Volts DC
411:Cx486S-40
403:5 Volts DC
391:Cx486S-33
383:5 Volts DC
371:Cx486S-25
354:Bus Speed
244:Production
191:Cyrix 6x86
187:Cyrix 5x86
183:Successors
76:clock rate
890:"Cx486 S"
274:foundries
226:Intel 486
805:AMD Élan
764:Cx486DX4
620:Voltage
575:Cx486DX2
481:Voltage
363:Voltage
288:Variants
107:2 KB (S)
45:May 1993
42:Launched
945:"Cx486"
444:Cx486DX
314:integer
258:fabless
213:was an
164:History
122:Desktop
813:Am5x86
800:PC/104
623:Notes
617:Cache
484:Notes
478:Cache
366:Notes
360:Cache
296:Cx486S
133:x86-16
88:speeds
1042:(PDF)
905:"FPU"
875:(PDF)
809:Am486
438:80386
222:Cyrix
149:Cores
137:IA-32
103:cache
96:Cache
71:Max.
57:Cyrix
432:The
268:and
236:and
230:BIOS
209:The
202:and
791:SoC
737:8KB
717:8KB
697:8KB
677:8KB
657:8KB
637:8KB
558:8KB
538:8KB
518:8KB
498:8KB
420:2KB
400:2KB
380:2KB
329:x87
270:IBM
238:UMC
234:AMD
215:x86
101:L1
86:FSB
73:CPU
1058::
922:.
854:.
835:.
264:,
240:.
189:,
175:,
135:,
1044:.
1027:.
995:.
966:.
907:.
892:.
877:.
860:.
839:.
206:.
156:1
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
