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

From: John Robertson <jrr_at_flippers.com>
Date: Wed May 08 2002 - 14:44:19 EDT

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Home today fighting a small chest infection... 
I don't think these ROM Signatures generated by the base numbers are true "Signatures" after all. Note that the coding for them does not follow the convention of using HP's ACFHPU, rather the "signature" generated uses standard HEX nomenclature.. Now I wonder what this number actually is...I'm going to try to use my new Arium ML1400 Logic Analyzer to see if I can find the section of code in the base that actually is used to create the ROM signature and report back. 
I think it is more likely a signature similar to the one ROMIDENT uses... anyone know it's root formula? 
John :-#)# 
At 10:06 AM 07/05/2002 +0100, Phillip Eaton wrote: 
<blockquote type=cite class=cite cite>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 
<a href="http://www.phillipeaton.com/" eudora="autourl">http://www.phillipeaton.com</a> 
---- 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 
>> > [<a href="mailto:owner-techtoolslist@www.flippers.com" eudora="autourl">mailto:owner-techtoolslist@www.flippers.com</a>]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 
>> > 
>> > 
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Received on Wed May 08 14:44:19 2002

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