Date   : Sun, 03 Aug 2003 22:48:42 +0100
From   : "C Alastair Seggie" <alastairseggie@...>
Subject: Re: BBC controlled lathe (Re: BeebEm Development)

Graham

> Worst case scenario, the GAL is protected (highly likely) and the
Eprom is
encrypted, using the GAL as a source for decryption. <

>From what Mark told me the ROM is not encrypted. The GAL might be
protected but I cannot be sure as this ROM and carrier belongs to
someone else and I was told that even trying to read it might destroy
it.

> Only other thing I can think of is to have some software intercepting
the
data as it passes into the paged area to give an idea of whats going
on.<

Mark did something like that, ran a program that input Values and then
recorded the output. I will send you the program and the output perhaps
you can make head or tail of this.

Alastair

-----Original Message-----
From: Graham [mailto:bbc@...] 
Sent: 03 August 2003 22:13
To: C Alastair Seggie
Subject: RE: BBC controlled lathe (Re: [BBC-Micro] BeebEm Development)

At 21:13 03/08/2003 +0100, you wrote:
>Thank you very much Wouter I will follow this lead. 
>
>I have been looking for a ROM for my Denford Starturn lathe for about 2
>years now. I have seen many different people in Scotland, Wales and
>England. I have covered about 1500 miles in the UK, spoken to people
>from as far a-field as Australia and India, all in search of this
little
>ROM.
>
>I have the software now thanks to a kind gentleman called Spike. I even
>have dumps of the ROM from his BBC. The problem is not the ROM itself
>but the carrier it is inserted into, before being placed in the BBC. 
>See this link for pictures: 8bs.com/substarturn.htm  
>
>The carrier has a GAL that seems to intercept the signals then send
them
>on to the ROM. 

Its possible that this GAL has data in it that the programme needs to
run
correctly.  Without the original, it may be impossible to get it
running.  

It *could* however, just be using some kind of lookup table in order to
compare what it gets back from the GAL and to what its expecting (a very
simple protection mechanism) therefore it would be quite easy, but I
suspect that if someone has gone to the trouble of adding additional
hardware into the mix, it could be much more difficult.

Worst case scenario, the GAL is protected (highly likely) and the Eprom
is
encrypted, using the GAL as a source for decryption.  

Only other thing I can think of is to have some software intercepting
the
data as it passes into the paged area to give an idea of whats going on.

[snip]