Re: Centipede and HP5004a

I encountered the same exact situation a few months back and sent a few
emails (maybe to John as he had some suggestions) at the time. I also
built a NOP fixture for the Centipede baord and was using a 5004a
signature analyzer. I could probably dig up the recorded results and
they will probably agree 100% with your results. I dug around for a
while looking for reasons but ended up generating my own list of
signatures based on a known good board.

One thing I did find in some documentation (
http://www.spies.com/~arcade/TE/SigAnalNotes.pdf - on page 14 of the pdf
document) an interesting table that lists a table with different
processors ans some signatures for each address line. As for the 6502,
it lists to separate values, just the 6502 and another 6502-A footnoted
with a phrase of 'Atari games will use a KK 6502-A NOP. The signatures
will be the same as for an 8080.' If you compare the two bits of
information for each type to values you can record, it is simple to see
what you have built (as I did) as opposed to what you need to match the
other values throughout the analysis guide furnished by Atari. If I
remember correctly, my results matched the 6502 list, but it has been a
while.

6502
A0 - UUUU
A1 - FFFF
A2 - 8484
A3 - P763
A4 - 1U5P
A5 - 0356
A6 - U759
A7 - 6F9A
A8 - 7791
....

6502-A
A0 - UUUU
A1 - 5555
A2 - CCCC
A3 - 7F7F
A4 - 5H21
A5 - 0AFA
A6 - UPFH
A7 - 52F8
A8 - HC89
...

I eventually just built my own signature list for a known working board
with the fixture I had built as the Signature analysis numbers are not
really a true measurement other than a certain number of clock cycles
that pass before an signal is encountered - correct me if I am wrong on
that anyway. There are some interesting articles on Al's sight
regarding the use of signature analysis if anyone is bored.

So I guess to help the question along, I think what we need to know is
what do you do differently to build a NOP ficture to produce results for
a 6502 (same as the 6800 signatures) as opposed to the 6502-A (same as
the Z80 and the 8080 signatures)?

I sure am glad someone duplicated my results. I look forward to any
answers that can set this straight.

On a separate note - is anyone interested in a HP5004a signature
analyser? I haven't used it since.

Greg

SteveT wrote:

>
>
>> > I just got a hp5004a , trying to use it to help repair a sick
>> >
>> centipede board. I built a NOP adapter (processor and socket)
>>
> It works perfectly. Signatures match the docs for the NOP adapter but
> they do NOT match what is published on the centipede schematics
> starting right at the micro. What Am I missing here? Is there
> something about the cat box I'm not taking into account here. Anyone
> out there using the HP5004a with centipede?
>
> Steve
>
>
Received on Sun Oct 27 19:06:33 2002