535:. Its instruction set is exactly the same. Motorola claimed in some marketing literature that it executes some instructions 40% faster than a 68881 at the same clock speed, though this did not reflect typical performance, as seen by its more modest improvement in the table below. The 68882 is pin compatible with the 68881 and can be used as a direct replacement in most systems. The most important software incompatibility is that the 68882 uses a larger FSAVE state frame, which affects
517:
36:
133:
170:
494:
The 68881 has eight 80-bit data registers (a 64-bit mantissa plus a sign bit, and a 15-bit signed exponent). It allows seven different modes of numeric representation, including single-precision floating point, double-precision floating point, extended-precision floating point, integers as 8-, 16-
507:
The CPU/FPU pair are designed such that both can run at the same time. When the CPU encounters a 68881 instruction, it hands the FPU all operands needed for that instruction, and then the FPU releases the CPU to go on and execute the next instruction.
503:
floating-point standard. It was designed specifically for floating-point math and is not a general-purpose CPU. For example, when an instruction requires any address calculations, the main CPU handles them before the 68881 takes control.
160:
microprocessors. These coprocessors are external chips, designed before floating point math became standard on CPUs. The
Motorola 68881 was introduced in 1984. The 68882 is a higher performance version produced later.
808:
197:
to execute the instruction's equivalent using 68020 integer-based software code, return an error to the program, terminate the program, or crash and require a reboot.
801:
656:
These statistics came from the comp.sys.m68k FAQ. No statistics are listed for the 16 MHz and 20 MHz 68882, though these chips were indeed produced.
177:
The 68020 and 68030 CPUs were designed with the separate 68881 chip in mind. Their instruction sets reserved the "F-line" instructions – that is, all
794:
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100:
72:
1197:
79:
119:
830:
53:
86:
57:
17:
1364:
68:
185:
digit "F" could either be forwarded to an external coprocessor or be used as "traps" which would throw an
786:
1369:
520:
759:
712:
1359:
1170:
578:
46:
1079:
528:
686:
539:
and other preemptive multitasking OSes that had to be modified to allocate more space for it.
1354:
912:
781:
93:
965:
856:
817:
496:
8:
149:
1017:
1012:
960:
846:
692:
594:
1007:
1002:
997:
992:
987:
735:
548:
190:
186:
1272:
1256:
1251:
1246:
1229:
1224:
975:
902:
897:
892:
887:
882:
193:. If an FPU is not present in the system, the OS would then either call an FPU
1288:
1239:
1093:
1088:
1052:
955:
950:
945:
940:
935:
930:
925:
920:
665:
598:
582:
157:
153:
1348:
1216:
1160:
1145:
869:
864:
566:
1324:
1234:
1140:
1131:
1121:
1112:
875:
590:
562:
152:(FPUs) used in some computer systems in conjunction with Motorola's 32-bit
816:
1126:
1117:
1055:
593:. Some third-party Amiga and Atari products used the 68881 or 68882 as a
532:
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1150:
1136:
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782:
freescale.com - Motorola MC68000 Family
Programmer's Reference Manual
555:
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1309:
35:
586:
500:
194:
1103:
1040:
1035:
132:
499:
format. The binary floating point formats are as defined by the
1314:
685:
Sterling, Thomas; Anderson, Matthew; Brodowicz, Maciej (2017).
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178:
1155:
1027:
622:
551:
1329:
1178:
536:
527:
The 68882 is an improved version of the 68881, with better
761:
MC68882 Technical
Summary HCMOS Floating Point Coprocessor
714:
MC68881 Technical
Summary HCMOS Floating Point Coprocessor
978:
684:
668:, floating point support was included in the CPU itself.
688:
High
Performance Computing: Modern Systems and Practices
169:
818:
Motorola-Freescale-NXP processors and microcontrollers
60:. Unsourced material may be challenged and removed.
1346:
736:"Frequently Asked Questions (FAQ) comp.sys.m68k"
802:
767:, MC68000 Family Reference Manual, Motorola
720:, MC68000 Family Reference Manual, Motorola
495:and 32-bit quantities and a floating-point
809:
795:
120:Learn how and when to remove this message
515:
168:
131:
14:
1347:
206:Motorola 68881/68882 series registers
790:
729:
727:
652:50 MHz version ran at 528 kFLOPS
649:40 MHz version ran at 422 kFLOPS
646:33 MHz version ran at 352 kFLOPS
643:25 MHz version ran at 264 kFLOPS
630:25 MHz version ran at 240 kFLOPS
627:20 MHz version ran at 192 kFLOPS
531:, and eventually available at higher
1196:
733:
547:The 68881 or 68882 were used in the
189:, handing control to the computer's
58:adding citations to reliable sources
29:
24:
724:
25:
1381:
691:. Morgan Kaufmann. p. 459.
621:16 MHz version ran at 160 k
34:
200:
45:needs additional citations for
829:
752:
705:
678:
13:
1:
671:
472:Instruction address register
27:Computer floating-point unit
7:
734:Boys, Robert (1996-01-06).
640:176,000 transistors on-chip
615:155,000 transistors on-chip
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164:
10:
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242:
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244:Floating point registers
1080:Memory management units
840:Industrial control unit
579:Convergent Technologies
524:
174:
137:
519:
172:
135:
497:Binary-coded decimal
173:A Motorola 68882 FPU
150:floating-point units
54:improve this article
1365:Integrated circuits
618:12 MHz version
207:
181:beginning with the
664:Starting with the
597:peripheral to the
525:
463:Accrued Exception
205:
175:
138:
136:Motorola 68881 FPU
1342:
1341:
1338:
1337:
1187:
1186:
698:978-0-12-420158-3
523:of Motorola 68882
492:
491:
488:
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460:Exception Status
433:Exception Enable
361:
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130:
129:
122:
104:
16:(Redirected from
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1370:68k architecture
1199:Microcontrollers
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549:Sun Microsystems
418:Control register
367:
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212:
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191:operating system
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69:"Motorola 68881"
62:
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976:Embedded system
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481:32 Bit Address
445:Status register
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167:
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115:
109:
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63:
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51:
39:
28:
23:
22:
15:
12:
11:
5:
1383:
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1360:Floating point
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1053:Floating-point
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1032:
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1024:
1023:
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1020:
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666:Motorola 68040
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583:Atari Mega STE
560:Apple Computer
558:workstations,
554:workstations,
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411:(bit position)
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237:(bit position)
234:
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146:Motorola 68882
142:Motorola 68881
128:
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42:
40:
33:
26:
18:Motorola 68882
9:
6:
4:
3:
2:
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1293:DSPcontroller
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629:
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624:
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614:
613:
602:
600:
596:
595:memory-mapped
592:
588:
584:
581:MightyFrame,
580:
576:
572:
568:
567:NeXT Computer
564:
561:
557:
553:
550:
540:
538:
534:
530:
522:
518:
509:
505:
502:
498:
483:
477:
476:
473:
469:
465:
450:
449:
446:
442:
438:
436:Mode Control
423:
422:
419:
415:
412:
409:
404:
401:
396:
393:
388:
385:
380:
377:
372:
369:
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88:
85:
81:
78:
74:
71: –
70:
66:
65:Find sources:
59:
55:
49:
48:
43:This article
41:
37:
32:
31:
19:
1355:Coprocessors
1325:PowerPC 5000
1198:
1064:
1056:coprocessors
913:68000 family
876:Hitachi 6309
831:
760:
754:
743:. Retrieved
739:
713:
707:
687:
680:
663:
655:
563:Macintosh II
546:
533:clock speeds
526:
506:
493:
471:
444:
417:
410:
243:
236:
201:Architecture
176:
145:
141:
139:
116:
107:
97:
90:
83:
76:
64:
52:Please help
47:verification
44:
857:6800 family
183:hexadecimal
1349:Categories
1320:PowerQUICC
1151:PowerQUICC
966:DragonBall
874:see also:
832:Processors
745:2023-06-23
672:References
575:Amiga 3000
529:pipelining
454:Condition
80:newspapers
1266:16/32-bit
1213:6801/6803
1161:PPC e6500
1146:PPC e5500
981:-variants
556:IBM RT PC
457:Quotient
354:mantissa
351:exponent
340:mantissa
337:exponent
326:mantissa
323:exponent
312:mantissa
309:exponent
298:mantissa
295:exponent
284:mantissa
281:exponent
270:mantissa
267:exponent
256:mantissa
253:exponent
187:exception
110:June 2017
1289:DSP568xx
1137:PPC 74xx
1132:PPC e500
1113:PPC e200
961:ColdFire
740:faqs.org
605:Versions
569:, Sharp
565:family,
501:IEEE 754
195:emulator
165:Overview
1127:PPC 7xx
1118:PPC 6xx
1104:PowerPC
1041:MC88110
1036:MC88100
1018:68LC060
1013:68EC060
1008:68LC040
1003:68EC040
998:68EC030
993:68EC020
988:68EC000
478:
451:
424:
370:
179:opcodes
94:scholar
1315:MPC5xx
1310:M·CORE
1303:32-bit
1282:24-bit
1257:68HC16
1252:68HC12
1247:68HC11
1230:68HC08
1225:68HC05
1106:family
1058:(FPUs)
903:68HC16
898:68HC12
893:68HC11
888:68HC08
883:68HC05
695:
660:Legacy
591:Falcon
589:, and
571:X68000
484:FPIAR
96:
89:
82:
75:
67:
1273:683xx
1207:8-bit
1156:QorIQ
1094:68851
1089:68451
1082:(MMU)
1070:68882
1065:68881
1028:88000
956:68060
951:68040
946:68030
941:68020
936:68012
931:68010
926:68008
921:68000
847:14500
776:Notes
765:(PDF)
718:(PDF)
635:68882
623:FLOPS
610:68881
599:68000
552:Sun-3
543:Usage
512:68882
466:FPSR
439:FPCR
158:68030
154:68020
101:JSTOR
87:books
1330:i.MX
1240:RS08
1221:6804
1217:6802
1179:i.MX
1141:e600
1122:e300
870:6809
865:6800
693:ISBN
537:UNIX
402:...
394:...
386:...
378:...
357:FP7
343:FP6
329:FP5
315:FP4
301:FP3
287:FP2
273:FP1
259:FP0
228:...
220:...
148:are
144:and
140:The
73:news
1235:S08
1171:ARM
979:68k
521:Die
156:or
56:by
1351::
738:.
726:^
601:.
587:TT
585:,
577:,
573:,
430:0
427:0
348:±
334:±
320:±
306:±
292:±
278:±
264:±
250:±
1139:/
1120:/
810:e
803:t
796:v
748:.
701:.
406:0
398:7
390:5
382:3
374:1
232:0
224:3
216:9
123:)
117:(
112:)
108:(
98:·
91:·
84:·
77:·
50:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
