80386 Multiplication and Division
nand2mario.github.io
80386 Multiplication and Division
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Re: 80386 Multiplication and Division
#2Excellent work. Thank you! Your 486 FPGA project looks pretty neat too.
Re: 80386 Multiplication and Division
#3No discussion of these instructions on the 386 would be complete without mentioning that early revisions had a bug in the 32-bit multiply: https://retrocomputing.stackexchange.com/questions/17803/int...
I wonder if anyone outside of Intel has discovered the actual bug in the circuitry yet.
Re: 80386 Multiplication and Division
#4Is there a rational explanation on why there seems to be a HN article answering the weirdest questions i had in my mind just a few days ago ?
Only yesterday i wondered how did CPU performed division. I didn't ask or type anything about it. It was just in my mind. And now this.
Are we part of a collective mind ? Do social networks algorithms shape society that deeply that we all end up having about the same random thoughts ?
This is really scary in a way.
Re: 80386 Multiplication and Division
#5Is there a rational explanation on why there seems to be a HN article answering the weirdest questions i had in my mind just a few days ago ? Only yesterday i wondered how did CPU performed division. I didn't ask or type anything about it. It was just in my mind. And now this. Are we part of a collective mind ? Do social networks algorithms shape society that deeply that we all end up having about the same random tho…
Not sure if it has a name but often there’s a trend of “one thing leads to another” related articles on the HN front page.
Yesterday there was something similar that might have planted a seed in your mind like it did for other people.
Re: 80386 Multiplication and Division
#6Is there a rational explanation on why there seems to be a HN article answering the weirdest questions i had in my mind just a few days ago ? Only yesterday i wondered how did CPU performed division. I didn't ask or type anything about it. It was just in my mind. And now this. Are we part of a collective mind ? Do social networks algorithms shape society that deeply that we all end up having about the same random tho…
The mind data-mines.
Re: 80386 Multiplication and Division
#7Is there a rational explanation on why there seems to be a HN article answering the weirdest questions i had in my mind just a few days ago ? Only yesterday i wondered how did CPU performed division. I didn't ask or type anything about it. It was just in my mind. And now this. Are we part of a collective mind ? Do social networks algorithms shape society that deeply that we all end up having about the same random tho…
Not sure if it has a name but often there’s a trend of “one thing leads to another” related articles on the HN front page. Yesterday there was something similar that might have planted a seed in your mind like it did for other people. https://news.ycombinator.com/item?id=46735133
Right. Or it could be frequency illusion. Once you become aware of something, it appears to be more frequent:
Re: 80386 Multiplication and Division
#8The 80186 and NEC Vxx chips - and of course also the 286 - could already do mul/div in one cycle per bit (+ some overhead for the microcode). What they didn't have was the early-out optimization.
The three-operand form of IMUL also already existed on those processors.
>This wasn't just an incremental upgrade—it was the foundation that would carry the PC architecture for decades to come.
AI?
Re: 80386 Multiplication and Division
#9The 80186 and NEC Vxx chips - and of course also the 286 - could already do mul/div in one cycle per bit (+ some overhead for the microcode). What they didn't have was the early-out optimization. The three-operand form of IMUL also already existed on those processors. >This wasn't just an incremental upgrade—it was the foundation that would carry the PC architecture for decades to come. AI?
> AI?
Probably not; this point is well justified by both theory and practice. Supporting suitably larger operands is indeed what naturally comes following the increase of computation demands.
One point I do differ from the author is that register width don't necessarily correlate with the size of address space. Even 8bit machines can address a large space by splitting apart the logical address and using multiple registers. Likewise, having a wide register does not imply the same address width.
Re: 80386 Multiplication and Division
#10The 80186 and NEC Vxx chips - and of course also the 286 - could already do mul/div in one cycle per bit (+ some overhead for the microcode). What they didn't have was the early-out optimization. The three-operand form of IMUL also already existed on those processors. >This wasn't just an incremental upgrade—it was the foundation that would carry the PC architecture for decades to come. AI?
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