Questions tagged [80387]

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What happens if an invalid opcode is executed on a 287/387 math coprocessor?

https://groups.google.com/g/comp.os.msdos.programmer/c/Lds3MJAgSl0/m/y8zfPt-bMskJ I assume that the 287/387 math coprocessors do not have the same illegal opcode exception that the 286/386 processors ...
Yuhong Bao's user avatar
13 votes
0 answers
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Is it possible to trap 387 FPU opcodes on a 287 connected to a 386?

The 8087 and 287 FPUs were designed before the IEEE 754 standard was released. Because of this, they contain some instructions which are not compliant with it. When the 387 was released in 1987, it ...
DarkAtom's user avatar
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8 votes
3 answers
726 views

Did the ARM-1 really outperform the 387?

According to a comment on https://news.ycombinator.com/item?id=31985142 The first benchmarks indicated the plain Archimedes had higher FP throughput than a 16MHz 386 with a 387. The original ...
rwallace's user avatar
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13 votes
2 answers
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How is the ‘Coprocessor segment overrun’ exception supposed to be handled?

The Intel 80386 CPU didn't have an on-board x87 FPU (maybe with the exception of some non-Intel clones). It was, however, able to use either a 80287 or 80387 as an external FPU. When the x87 FPU ...
DarkAtom's user avatar
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7 votes
1 answer
645 views

80387 transistor count

In 1985, Intel released the 80386, a particularly complex and sophisticated microprocessor for its day, consisting of 275,000 transistors, a rather large number for the day. How many transistors went ...
rwallace's user avatar
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3 votes
1 answer
715 views

What is this socket for in 386 notebook motherboard

What is this socket for on 386 motherboard? I have no manual, no documentation and no resources readily available for this machine (Commodore C386SX-LT). Source: Probably oldcrap.org Close-up: ...
Bartek Malysz's user avatar
17 votes
3 answers
3k views

x87 trigonometric instructions

The 8087 has instructions FPTAN and FPATAN, which are Partial Tangent and Partial Arctangent. The "partial" is presumably is to do with the range of the operands. For FPTAN the operand must be less ...
Single Malt's user avatar
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