[BBC-Micro] Reversing the Tube ULA (destructively)

Ed Spittles percy.p.person at gmail.com
Fri Oct 29 13:50:11 BST 2010


On 28 October 2010 21:21, Pete Turnbull <pete at dunnington.plus.com> wrote:

> Pete Turnbull wrote:
>
> > Nor will battery acid, which is not especially concentrated sulphuric
> acid.
>
> Well, for your edification and delight, I tried an experiment a little
> earlier this evening.


I am both edified and delighted!  However...

On 26 October 2010 01:46, Philip Pemberton <philpem at philpem.me.uk> wrote:

> On Tue, 2010-10-26 at 00:14 +0100, Theo Markettos wrote:
> > We[1] have suitable microscopes, though fuming nitric acid is Frowned
> Upon
> > by the university health and safety people and I'm not trained with it.
>  But
> > if anyone can do the depackaging (and I can tell you what to do) then I
> can
> > image it.
>
> It might be worth sending a chip to one of the professional decapping
> services ...

http://www.crownhillmobile.com/IC_De_Cap.htm (these guys appear to be
> based in the UK)


Great! They say prices start from £25 to dissolve down to a bare die: I'll
stump up (or chip in) for that if someone (perhaps Mark) can provide a Tube
ULA, and  if someone (perhaps Theo) can get suitable high resolution photos
of the result.

On 29 October 2010 01:02, Mark Haysman <jumbos.bazzar at btopenworld.com>wrote:

> I'll keep an eye out for a dead one to experiment on. If we were going to
> submit it to a lab for proper deconstruction, I don't mind supplying a
> known
> good one for that.
>

This could be the solution!  I'd be surprised if no-one on the list has a
broken second processor - but will anyone be prepared to donate the
presumed-useless Tube chip?  It still bothers me to destroy a working one.

But also, in your photo of the 3 generations:
http://www.retroclinic.com/misc/tubechips.jpg
isn't the top one plastic packaged?  Would that be depackageable with
acetone?


> Whilst it's not the Tube ULA, the Electron one is much easier to open...
>
> http://retroclinic.com/misc/12c021.jpg
>
> Gives an idea of what they look like inside, albeit this one is larger, 12
> cell instead of 9.


Interesting - you know that the Tube ULA is a size 9?  Ah, I see it's on the
markings ULA9C018E-7 8504

BTW, I mentioned earlier abrasion for chip+pin, and in fact I was thinking
of Nohl and Evans and the Mifare/Oyster work:
http://www.usenix.org/events/sec08/tech/nohl.html
"Once we had isolated the silicon
chips, we removed each successive layer through me-
chanical polishing, which we found easier to control than
chemical etching. Simple polishing emulsion or sandpa-
per with very fine grading of 0.04µm suffices to take off
micrometer-thick layers within minutes."


Cheers
Ed
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