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Comment by kens | Hacker News Reader

Author here, if anyone has questions about the 8086.

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 :)

I'm working on a simulator :-)

(That sounds brilliant!)

Using an HDL like Verilog or VHDL? Something else?

I'm planning on a visual6502-style simulator in a browser.

Oh fantastic! this makes me super happy to hear :) I'd love to play with it.

What is the most recent generation of Intel cpu for which an optical microscope can see enough to (at least theoretically) do what you are doing with the 8086.

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?

Oops, yes you are correct. Now I need to fix my diagram :(

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?

I use f5bot.com, a free service that checks Reddit, Hacker News, and Lobsters for keywords.

You could use an analytics tool like Google Analytics to see referrer data.

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?

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.

I think it'd be interesting to see a bit of that process in a blog post. Maybe something about how you do what you do and how your techniques have progressed? Even if it's a hacky mess, it sounds neat.

Is it true that lots of embedded system today still use a 8086 of some kind, because they're really cheap/easy to understand?

I think the Intel 8051 is still used in embedded systems. I don't know about the 8086 but it wouldn't surprise me.

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.

If they are still manufactured, which process is used?

I guess even a 65nm 8086 would be tiny.

And lightning fast.

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.

An 80186 core was reasonably popular in LCD controllers (for OSD etc.) and miscellaneous stuff a while ago:

https://www.cpushack.com/2013/01/12/the-intel-80186-gets-tur...

These days, I think 8051 has taken over due to their smaller die area, and the increased clock frequencies due to smaller process sizes have made their performance sufficient.

x86 is a fairly uncommon choice in embedded systems, but it does show up occasionally. The DisplayPort to HDMI chip used in some current-generation Apple laptops has an embedded 80186 core, for example.

What you will find all over are 8051-compatible cores. Those show up everywhere, even in some places where you might not have expected to find a microcontroller at all.

i don't have any questions but i do have a lot of appreciation

thank you for writing this series

Thanks! It's nice to know that people are finding it interesting.

Out of the 20000 you counted, which transistor is your favorite?

I'd pick a driver transistor in the charge pump because it's kind of wild to have this analog circuit generating negative voltage in this otherwise digital chip.

Does there exist a logic gate diagram of the 8086, or similar cpu's (e.g. 6502)? I mean a way to see the discrete digital logic, as opposed to transistors, of the ALU and also any other random logic and control.

Always an informative read, thank you so much, Ken!

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