Ferranti ULA doc may be of interest

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Moggy
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Ferranti ULA doc may be of interest

Post by Moggy » Tue Nov 01, 2011 3:59 pm

I posted this some time ago in the old ts1000 forum, may be of interest even if only academic.


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Moggy
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Andy Rea
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Re: Ferranti ULA doc may be of interest

Post by Andy Rea » Fri Jul 13, 2018 11:25 pm

Having done a search this thread seems like a good match... i stumbled upon this today interesting stuff

https://ia801203.us.archive.org/21/item ... asheet.pdf

now then if any is clever enough to decap a ULA and photograph the final layer, it would be possible to reconstruct the exact logic hiding inside the little vlack chip :mrgreen:

regards Andy
6 x ZX81, 1 x TS1500 , 1 x +3e, 1 x timex 2040 printer, 1 x timex 2020 cassette deck, siclair printer and some spectrum

Moggy
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Re: Ferranti ULA doc may be of interest

Post by Moggy » Sat Jul 14, 2018 1:14 pm

I'm almost sure Mark posted something re this PDF some time ago and gave an explanation of the ULA's heat output being due to,amongst other things, a collection of voltage regs scattered about the chips periphery.

As for the decapping I have seen a collection of stills for the 81(I'm aware of the many spectrum ones) but have lost the link I thought I'd bookmarked. :oops:

I wouldn't bother though because some dodgy geezer in the Midlands is shipping them out by the bucketful. :lol:

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Andy Rea
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Re: Ferranti ULA doc may be of interest

Post by Andy Rea » Sat Jul 14, 2018 10:19 pm

Moggy wrote:
Sat Jul 14, 2018 1:14 pm

As for the decapping I have seen a collection of stills for the 81(I'm aware of the many spectrum ones) but have lost the link I thought I'd bookmarked. :oops:
I carry on digging :lol:
6 x ZX81, 1 x TS1500 , 1 x +3e, 1 x timex 2040 printer, 1 x timex 2020 cassette deck, siclair printer and some spectrum

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RetroTechie
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Re: Ferranti ULA doc may be of interest

Post by RetroTechie » Fri Jul 20, 2018 10:33 pm

Pretty useless in practical sense. But nice reading material anyway. :D
Andy Rea wrote: now then if any is clever enough to decap a ULA and photograph the final layer, it would be possible to reconstruct the exact logic hiding inside the little vlack chip :mrgreen:
Getting at the bare IC die isn't the hard part... Probably would have sacrificed a few IC's for this purpose myself, IF there was some easy way to tell what you're looking at. :?

Seeing some metal strips on the IC die or following connections from a bond pad around is one thing. But is that a P-channel or N-channel FET? Or just an integrated resistor / tiny capacitor? Or for a ROM area, yeah you could perhaps spot the 1's and 0's in there. But what's the rows & what's the columns? How are those bits used inside the IC? Never mind that some structures may only become visible after 1 or more layers of material are etched away.

Wish there was some easy guide for this. Several examples to be found these days (with pics 8-) ). But a how-to for someone who's never seen an IC die up close.. haven't come across that (yet).

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