[HN Gopher] Counting the transistors in the 8086 processor: it's...
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Counting the transistors in the 8086 processor: it's harder than
you might think
Author : zdw
Score : 109 points
Date : 2023-01-14 18:42 UTC (4 hours ago)
(HTM) web link (www.righto.com)
(TXT) w3m dump (www.righto.com)
| psacawa wrote:
| Very interesting.
|
| Anyone has any idea about the technology that could be used for
| imaging more dense ICs and multilayer PCBs? In a presentation
| elsewhere, Ken says that he used a metallurgical telescope and
| USB microscope. So the imaging is done with visible light and
| limited resolution. It is enough for old chips, e.g. the 8086
| discussed in this article is made with a 3um process.
|
| As I look around I see recent Intel chips haven't been reversed.
| [0] There are allusions to x-ray tomography and electron
| microscopes [1]. Anyway a plebs can get close for cheap?
|
| [0]
| https://reverseengineering.stackexchange.com/questions/5878/...
|
| [1] https://www.youtube.com/watch?v=WOZqoTuAGKY
| kens wrote:
| There's a reason I mostly stick to chips from the 1970s.
| Moore's law makes reverse engineering (literally) exponentially
| harder for later chips. Multiple layers of metal on the make it
| much more difficult; you can remove layer-by-layer but it's
| very hard. An electron microscope helps, and you can get one
| for semi-hobbyist prices if you try. X-ray tomography looks
| like a cool technology but it is very cutting edge and
| extremely expensive. See: https://spectrum.ieee.org/chip-x-ray
| klelatti wrote:
| Another great post from Ken - thanks again for all your work.
|
| Looking at the transistor / vacancy counts for microcode it
| struck me just how this reduces the count of those used for logic
| in the rest of the CPU - down to less than 12,000 I think. [1]
|
| The 8086's competitor the Z8000 had c17,500 and didn't use
| microcode so must have been significantly more complex to design
| - so giving Intel the advantage in getting to market first.
|
| [1] This ignores the transistors used for registers etc.
| neonate wrote:
| http://web.archive.org/web/20230114190129/http://www.righto....
| kens wrote:
| Author here, if anyone has questions about the 8086.
| diffuse_l wrote:
| In the enlarged photo of the ROM transistors, the transistor in
| the third row, second column, seems like it should be marked as
| disconnected.
|
| Should it? Or is there something I'm missing in the way the
| transistors are connected?
| kens wrote:
| Oops, yes you are correct. Now I need to fix my diagram :(
| kragen wrote:
| i don't have any questions but i do have a lot of appreciation
|
| thank you for writing this series
| kens wrote:
| Thanks! It's nice to know that people are finding it
| interesting.
| [deleted]
| java-man wrote:
| Always an informative read, thank you so much, Ken!
| metadat wrote:
| How did you actually count the transistors? Was it a completely
| maddening manual process or did you develop a tool or other
| approach to reduce toil and preserve sanity?
| kens wrote:
| I traced out the layers of the chip using GIMP, which was
| tedious and took several days. I have a super-hacky program
| that extracts transistors from these layers, figures out
| connectivity, and generates gates from the transistors. So I
| didn't need to count the transistors one-by-one, but I did
| need to trace out each one.
| bit-hack wrote:
| You mention that you have traced out every transistor from die
| photos, and I was wondering how much work there would be to
| make a netlist for the 8086 like that which was used to produce
| the visual 6502 simulator?
|
| It that feasable or is there lots of work to do to get to that
| stage?
|
| I'm loving your series on the 8086 btw :)
| kens wrote:
| I'm working on a simulator :-)
| tpmx wrote:
| (That sounds brilliant!)
|
| Using an HDL like Verilog or VHDL? Something else?
| kens wrote:
| I'm planning on a visual6502-style simulator in a
| browser.
| bit-hack wrote:
| Oh fantastic! this makes me super happy to hear :) I'd love
| to play with it.
| dtgriscom wrote:
| Off-topic: how do you you find out that your site has been
| mentioned on Hacker News? Do you notice a surge in traffic? Do
| you check Hacker News periodically? Did you feel a disturbance
| in the force?
| kens wrote:
| I use f5bot.com, a free service that checks Reddit, Hacker
| News, and Lobsters for keywords.
| netr0ute wrote:
| Is it true that lots of embedded system today still use a 8086
| of some kind, because they're really cheap/easy to understand?
| kens wrote:
| I think the Intel 8051 is still used in embedded systems. I
| don't know about the 8086 but it wouldn't surprise me.
| wildzzz wrote:
| 8051 is the basis for many microcontrollers today. They
| aren't compatible since vendors add all kinds of custom
| instructions or modifications to the original design but
| some vendors do still make drop in replacements. You can
| also get soft core versions for FPGAs that can run original
| software.
| forinti wrote:
| If they are still manufactured, which process is used?
|
| I guess even a 65nm 8086 would be tiny.
| BirAdam wrote:
| Production of the 8086 by Intel stopped in 1998. I imagine
| that it may have continued by another manufacturer, but I
| doubt it. 8051 descendants/derivatives are manufactured,
| but no longer by Intel.
|
| In general ARM and RISC-V have taken much of the low end
| market and microcontroller market.
| anticensor wrote:
| And lightning fast.
| fijiaarone wrote:
| This is what happens tv becomes unwatchable.
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