Extracting ROM constants from the 8087 math coprocessor's die

Re:Extracting ROM constants from the 8087 math coprocessor's... by userbinator on Saturday May 16, 2020 @05:10PM (#23207251)

The exponents may be implied by how the microcode uses them, somewhat like how fixed-point maths assumes the position of the decimal(binary) point.

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Re:Extracting ROM constants from the 8087 math coprocessor's... by atq2119 on Sunday May 17, 2020 @06:03AM (#23210927)

Some exponents might also be stored explicitly in the microcode ROM. Which is perhaps just another way of saying the same thing as you're saying.

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Re:Extracting ROM constants from the 8087 math coprocessor's... by amelius on Sunday May 17, 2020 @06:19AM (#23210986)

Also, the first bit of the mantissa is always 1 (except for the number 0), so they could have left it out.

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Re:Extracting ROM constants from the 8087 math coprocessor's... by kens on Sunday May 17, 2020 @12:46PM (#23213198)

In its external representation, the 8087 omitted the leading one for the reason you suggest; it is redundant.

Your suggestion could apply to the ROM; they could have hard-coded the first bit to 1, saving a row in the ROM. I think they could have avoided a few transistors by doing this.

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