Re: CAT box clock source

On Mon, 12 Jan 1998, Al Kossow wrote:

> Did someone say that they had the manual for the
> HP 5004? I haven't used signature analysis before
> for debugging.. Does it just recognize a repeating
> pattern at a particular node in a circuit, or does
> it generate a fixed 16 bit value based on some
> number of input states?
>

        It just calculates a 16-bit CRC of some data stream. You can get
the polynomial from the CAT box schematics. There is a page that has the
LFSR on it (4 LS164s, with 3 or 4 XOR gates feeding the input.) I forget
exactly which outputs get fed back.

        There are start and stop inputs to the sig. analyzer which tell it
when to start and stop compacting the data.

        The Cinematronics way to do sig. analysis was to use the exorcisor
to keep injecting a fixed stream of data into the CCPU, so that the
signatures are always the same. Basically that's what needs to be done
for signature analysis -- the CPU needs to be put into some sort of test
state, where predictable signatures can be read.

Joe
Received on Mon Jan 12 13:20:06 1998