RE: Gottlieb / Q*bert scripts for the 9010A/9100

Ah ha! You've just spotted the reason for my previous
question - What's the polynomial?

I worked out the Cat Box polynomial directly from the PCB,
you can actually _see_ the address counter and the XOR
feedback points. Apparently the Cat Box polynomial is the
same as the HP one.

Now it gets a bit confusing... (Especially as I've not
actually had time to get stuck into my Fluke and confirm all
of this!)

/As far as I can see/ The Fluke creates a signature with a
similar procedure to a boring old checksum, by reading each
byte of a region of memory space and performing a calculation
on it to produce a single 16 bit signature. To create the
signature, it right shifts each bit of each byte into the
polynomimial XOR 'circuitry'. On the Cat Box the 'circuitry'
is physical, but is probably software on the 9010a for
reasons shown below.

On a Fluke, there seems to be a bit of general confusion as
to where the calculation is done, in the pod or in the main
unit. I would be very surprised if it were done in the pod
but I could be wrong. (I hope to have a look myself in the
summer, when I've finished college...)

Anyway, the Cat Box performs Signature /Analysis/, which also
produces a signature, but not by reading in a chunk of bytes
and creating a signature from them via software.

Using a probe, it reads the chain of bits that occur at a
particular point on a PCB when the address bus is ramped from
0 to FFFFH. To test one part of a circuit e.g. a single ROM,
you would tie a sig analysis start and stop line to the chip
enable of the ROM which in effect maps to that ROMs address
space only.

If you point the probe at the one data line of the ROM, you
will get a stream of bits which you can XOR in a similar way
to the standard Fluke signature. BUT the calculation will
only be performed on one bit of each byte as there are 8 data
lines and you only have one probe! Thus, you get 8 signatures
per ROM as shown in the Atari Cat Box signature reference for
each PCB.

A Fluke signature is an improved way of testing a ROMs
integrity over a checksum, but it can't be used to analyse
anything other than a fixed areas of memory space i.e. ROM.
Signature /Analysis/ can test /any/ digital part of a circuit
as long at it derives from the processor's address and data
decoding (i.e you can't do the video circuitry).

My program uses a software way of calculating the signature,
but it emulates the Atari probe hardware i.e. by testing only
1 bit of a byte and thus it is an emulator, as opposed to
just a signature generator.

I originally wrote it to do the 8 bits of a ROM, but this
added an extra loop, and all I was really trying to do was
show how it worked, so I went back to just one bit for
clarity.

Note BASIC has no bitwise operators so the code is a bit
cumbersome, if you rewrote it in C, or even better Forth, it
would be a fraction of the size.

You could quite easily modify my emulation to either create
all 8 checksums together like the Cat Box or pass all of the
information from each byte serially into the calculation like
the Fluke (if you knew it's polynomial).

Cheers,
Phillip Eaton
http://www.phillipeaton.com

---- Original message ----
>Date: Mon, 06 May 2002 21:45:41 -0700
>From: John Robertson <jrr@flippers.com>
>Subject: RE: Gottlieb / Q*bert scripts for the 9010A/9100
>To: "Phillip Eaton" <inbox@phillipeaton.com>,
<TechToolsList@flippers.com>
>
>
>Hi Phillip,
>
>I just tried your emulator on a bunch of Asteroid files and
compared them
>with the signatures on the 9010 and I do not get the same
results... Does
>it not setup the same Signature that HP designed and thus
should it not
>give the same results for any file as the Fluke would do on
a ROM signature
>test? The signatures generated by your emulator are
consistent - identical
>files give identical signatures...
>
>Might I ask what the "Bit number <0 - 7>" refers to in the
emulator?
>
>John :-#)#
>
>At 11:08 PM 06/05/2002 +0100, Phillip Eaton wrote:
>
>
>>I wrote one of these a few years back. It's part of my
Atari Cat Box
>>signature analysis write-up which is held at
>>http://www.gamearchive.com/video/manufacturer/atari/vector/s
ignatures/
>>
>>It includes a very simple program source code (to aid
understanding) to do
>>what you mentioned in MS DOS QBasic for the Cat Box.
>>
>>You could quite easily use it as a base to write your own,
or simply change
>>the polynomial in mine and it'd do what you need.
>>
>>How did you work out the ploynomial?
>>
>>Cheers,
>>Phillip Eaton
>>
>> > -----Original Message-----
>> > From: owner-techtoolslist@www.flippers.com
>> > [mailto:owner-techtoolslist@www.flippers.com]On Behalf
Of John Robertson
>> > Sent: 06 May 2002 22:03
>> > To: TechToolsList@flippers.com
>> > Subject: Re: Gottlieb / Q*bert scripts for the 9010A/9100
>> >
>> >
>> >
>> > What we need is for some bright person to write a simple
utility that
>> > converts data files to signatures. The signature formula
is fairly simple
>> > and if combined with Bill Ung's ROMSUM would be a nice
tool for our
>> > package. If you don't know ROMSUM it is a dos utility
that will give a
>> > checksum listing plus the ROM size for a single or group
of files...
>> >
>> > The Signature process is a CRC process that uses the
following feedback
>> > equation: X(to the 16th) + X(to the 12th) + X(to the
9th) +X(to
>> > the 7th) +
>> > 1 or
>> > P(X) = X(15th) + X(9th) + X(7th) +X(4th) + 1
>> >
>> > So who wants to make a simple (not for me!) binary
program that
>> > allows one
>> > to input a file and outputs it's signature?
>> >
>> > John :-#)#
>> >
>> > At 09:11 AM 06/05/2002 -0400, Kev wrote:
>> >
>> >
>> >
>> > >Anyone written any test scripts for these or at the
very least have some
>> > >checksum signatures?
>> > >
>> > >Thanks,
>> > >Kev
>> >
>> >
>
Received on Tue May 07 02:54:21 2002