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Examining the silicon dies of the Intel 386 processor

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Re: Examining the silicon dies of the Intel 386 processor

#21

Post by peter_d_sherman »

I'm always interested in all things (80)386 because this was basically the processor that launched the 32-bit computing revolution, at least as far as popular adoption of computers based on this processor go (there were earlier 32-bit processors -- but no earlier processor became as commercially popular (or as adopted by the mass population) as much as the (80)386).

So this processor is of particular interest to me -- and should be to future computing historians...

This is truly a great article about that processor!

It's information rich (I have not seen a more information rich source about the 386 on the entire Internet, except for perhaps 386 technical manuals and manual fragments, but those documents lack general human readability), and it is of great value to anyone who wishes to study the 386, and it will be of great value to future computer historians...

So, well done!

Upvoted and favorited!

Re: Examining the silicon dies of the Intel 386 processor

#23

Post by kens »

srejk wrote: post #18
kens wrote: post #2

Author here. I've been looking at the 386 if anyone has questions. This post was inspired by userbinator's discussion on HN a couple of weeks ago about how many transistors there are in the 386.

Great post! Any idea how the turbo button worked? It seems like, given the transistor difference between the 8086 and 386, that merely decreasing the clock frequency wouldn't be enough?

Yes, I think the turbo button just changes the clock speed. The 386 was designed to be binary compatible with the 8086, but normally ran faster.

Re: Examining the silicon dies of the Intel 386 processor

#24

Post by kens »

macote wrote: post #20

Today I learned that the "s" in SX means "single" and "d" in DX means double. The DX has double the data bus width of the SX (32-bit vs 16-bit).

But then the 486 DX has a floating-point unit, while the 486 SX does not. So Intel just went with DX is better than SX.

Re: Examining the silicon dies of the Intel 386 processor

#25

Post by kens »

peter_d_sherman wrote: post #21

I'm always interested in all things (80)386 because this was basically the processor that launched the 32-bit computing revolution, at least as far as popular adoption of computers based on this processor go (there were earlier 32-bit processors -- but no earlier processor became as commercially popular (or as adopted by the mass population) as much as the (80)386). So this processor is of particular interest to me -…

Thanks for your kind comments!

Personally, I'd say that the IBM System/360 (1964) was the first widespread and influential 32-bit architecture. The Motorola 68000 (1979) also deserves a mention for its use in the Macintosh. (And I'll argue with anyone who says it wasn't a real 32-bit processor :-) But, yes, the 386 started the 32-bit x86 architecture on most (non-phone) computers today.

Re: Examining the silicon dies of the Intel 386 processor

#26

Post by irdc »

srejk wrote: post #18
kens wrote: post #2

Author here. I've been looking at the 386 if anyone has questions. This post was inspired by userbinator's discussion on HN a couple of weeks ago about how many transistors there are in the 386.

Great post! Any idea how the turbo button worked? It seems like, given the transistor difference between the 8086 and 386, that merely decreasing the clock frequency wouldn't be enough?

This was often done by introducing wait states, so the processor would slow down while accessing main memory.

Re: Examining the silicon dies of the Intel 386 processor

#29

Post by RetroTechie »

johnklos wrote: post #10
kens wrote: post #2

Author here. I've been looking at the 386 if anyone has questions. This post was inspired by userbinator's discussion on HN a couple of weeks ago about how many transistors there are in the 386.

Every time I see something new on righto.com, I get excited! I get to learn :D Thank you so much, both for constantly sharing what you know and for preserving what's one of the most interesting times in the evolution of computing.

+1

What I like most about these articles, is that it shows how messy even high-tech can be:

All the details in fabrication techniques (and its effect on what logic designers can/can't do), some opcodes removed to make room on the die for a bugfix (?, see note 26), etc etc. "Ultimately all digital electronics is analog".

The business mistakes, and lucky recoveries.

Keep up the good work, Ken! (btw you typo'd an "8" and "6" in note 25 :-)

Re: Examining the silicon dies of the Intel 386 processor

#30

Post by RachelF »

kens wrote: post #24
macote wrote: post #20

Today I learned that the "s" in SX means "single" and "d" in DX means double. The DX has double the data bus width of the SX (32-bit vs 16-bit).

But then the 486 DX has a floating-point unit, while the 486 SX does not. So Intel just went with DX is better than SX.

There were rumours that the DX and SX chips were exactly the same:

Intel zapped the FPU on the SX to disable it. Apparently it cost more to make, but sold for less.

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