Date   : Sat, 30 Oct 2010 19:13:46 +0100
From   : C.J.Thornley@... (Chris Thornley)
Subject: Reversing the Tube ULA (destructively)

No, I had not missed the point but if you would have asked I could have
clarified it a bit further.

These where links to a page where they had decamped some chips so I presumed
someone could contact the author for suggestions or method that could be
used to help you decap the chips you where having difficulty with.

If the chip is covered in plastic no acid going dissolve it away, not even
the nasty Hydrofluoric acid. 

This what also lead the infamous "John George Haigh" (acid bath murder) to
be captured "The body of his victim had been reduced to a hardened sludge
that coated the back yard, forensic investigators unearthed twenty-eight
pounds of human fat, the partly corroded bones of a human foot, Mrs.
Durand-Deacon's plastic handbag which had resisted the acid " 

You have to look at Esters, I believe Ethyl acetate might be worth trying.
You probably end up with the plastic turning into a sticky goo that need to
be scrapped off.

Chris


               />      Christopher J. Thornley is cjt@...
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-----Original Message-----
From: bbc-micro-bounces+c.j.thornley=coolrose.fsnet.co.uk@...
[mailto:bbc-micro-bounces+c.j.thornley=coolrose.fsnet.co.uk@...
uk] On Behalf Of Pete Turnbull
Sent: 28 October 2010 10:18 PM
To: bbc-micro@...
Subject: Re: [BBC-Micro] Reversing the Tube ULA (destructively)


J.G.Harston wrote:
> Christopher Thornley wrote:
>> The rom will need to be decaped first.
> 
> Why? ROMs can just be read directly. Loads of CoPro ROMs at 
> mdfs.net/tube

I wonder if Chris has missed the point of what I was describing and others
have been suggesting solvents for?  He's referring to a process used for
decapping microcontrollers that contain both CPU and mask ROMs (and which
can't be read out electronically), by using fuming nitric acid and acetone,
but perhaps he's meaning that in the context of exposing the die in the ULA?
As Jonathan points out, we have all the ROM code.  It's only the ULA layout
we need, and hence we've been discussing (im)possible solvents for
decapping.  The MAME pages are irrelevant.

-- 
Pete                                           Peter Turnbull
                                               Network Manager
                                               University of York

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