Re: 6702 chip

From: Groepaz <>
Date: Fri, 11 May 2012 06:32:20 +0200
Message-Id: <>
On Thursday 10 May 2012, you wrote:
> Having just coded up the VHDL for the CRC computations for both ethernet
> and HDLC then I would suspect that the internals of the 6702 are a state
> machine that depends upon the value written and the current value. The XOR
> operator and logical shifts (left or right) or rotates (left or right)
> will also come into the equation. So keep an eye out for these operators
> in the numbers that get spat out. As Segher has already hinted - convert
> the numbers to hex, octal or binary rather than decimal and you may see
> the pattern easier. If we can get a printout of the exact number sequence
> on this thread (and the values you poked in to obtain them) this would
> allow some degree of 'parallel processing' to the problem. Multiple
> hackers working in different time zones all with different ideas working
> on a single problem - either a recipe for disaster or success! Cheers,
> Dave

i'd start with feeding it a pattern that contains the minimum number of 1 bits 
which will still produce a non zero output (if it produces a non zero output 
with just zeros as input, even better). that should reveal quickly if it is 
some kind of lfsr, or something simpler.


Freedom of the press belongs to those who own one. 
<A. J. Leibling>

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Received on 2012-05-11 05:00:04

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