I'm incredibly pleased to announce that the microcode for the Intel 80386 has been decoded.

[gloriouscow@oldbytes.space]

@ldcd sorry what's a rough traveller?

I can get 286 chips to you but I have no real experience with or equipment for decapping here.

[gloriouscow@oldbytes.space]

@ldcd @infosecdj can you answer this?

[ldcd@social.treehouse.systems]

@gloriouscow just like a checklist for the process, IE any device cleaning steps, acid mixture, times and heating required, but the siliconpr0n linked is probably good enough

[infosecdj@infosec.exchange]

@gloriouscow @ldcd Aluminium, the die is too old to have any copper on it.

[gloriouscow@oldbytes.space]

@ldcd Yeah, I have no idea. I shouldn't be allowed in the average kitchen let alone a chemistry lab.

If you have unanswered questions I could get you in touch with someone, but they're the person who wrote that

[ldcd@social.treehouse.systems]

@infosecdj @gloriouscow ok perfect that's what I was hoping, shouldn't be too hard to etch off

[ldcd@social.treehouse.systems]

@infosecdj @gloriouscow how many delayered 286s do you have? My training is expired on the RIE tool and it's also super oversubscribed

[infosecdj@infosec.exchange]

@ldcd @gloriouscow Exactly one for now. Can make more if needed. Using RIE to strip the die is rather expensive though, just HF for oxide removal and spiked HCl for metal would do the job of getting to the substrate quickly.

[gloriouscow@oldbytes.space]

I think this image deserves a tiny bit of explanation. What are we looking at here?

Well, it's a direct mapping of the microcode array to a bitmap, where black (0) is no transistor and white (1) is a transistor.

Overlaid on the actual microcode die photo mosaic, it looks like this.

[ldcd@social.treehouse.systems]

@infosecdj @gloriouscow spiked HCl?

I don't do much semiconductor processing but I can give that a go; we're not allowed to bring any solvent to the acid bench so if you have any dies free of epoxy (but not necessarily delayered) that would be ideal

[gloriouscow@oldbytes.space]

Each microcode word on the 386 is 37 bits long. So each of these rows of microcode bits contributes one bit to the resulting microcode word.

A PLA activates the columns of the microcode ROM from above, column-wise, and from the left side, via multiplexers, ultimately activating exactly 37 cell positions for each microcode address.

[infosecdj@infosec.exchange]

@ldcd @gloriouscow Ah, adding some H2O2 to HCl speeds things up by a lot. Also makes it fume chlorine, so a fume hood is recommended for obvious reasons.

@gloriouscow do you think you could supply some? Both of you are likely on the same continent, no? Otherwise I can do it.