[Techtoolslist] Atari 6502A NOP adapter

[teeray]

OK Guys,

A 6502 NOP will not produce sig's that match Atari doc's.
Reason is the 6502 takes two clock cycles to do a NOP instruction.
The Cat Box takes one clock cycle.
So you get double readings of each address. All you need to do is make
an NOP using a couple of counter IC's to cycle through the address range
on each clock cycle. Or divide the clock by 2 and use this as your clock
connection for the Analyzer.  You can do this with one D type flip flop IC.

Tim


-----Original Message-----

>From: "martin at guddler.co.uk" <martin at guddler.co.uk>

>Sent: Jan 24, 2009 7:38 PM

>To: Technical Tools Mail List <techtoolslist at flippers.com>

>Subject: Re: [Techtoolslist] Atari 6502A NOP adapter

>

>Sorry guys, I should have said, I've got the doc. I've probably got  

>the one you're pointing too as well John. But I'll pick it up from TT  

>tomorrow if not, thank you.

>

>Nice to see the same people still reading as were here in 2002 as  

>well :)

>

>OK. Tomorrow ill put more thought into comparing the two CPUs. The  

>only thing that really springs to mind at the moment is maybe they've  

>messed with the order of the address lines or something?

>

>The really odd thing is I know for a fact I've fixed centipede boards  

>in the past with my 5006.

>

>Incidentally, I'm now using the 9100 for the sigs. I keep meaning to  

>post the programs up on my website but they need some refining. Error  

>trapping and the like. I've had it producing HP signatures for some  

>time now.

>

>I'll post back if I work anything out. Thanks for the pointers though.

>

>Martin.

>

>

>On Jan 24, 2009, at 20:39, John Robertson <jrr at flippers.com> wrote:

>

>> martin at guddler.co.uk wrote:

>>> Hi all,

>>>

>>> Just been trying to find information on what is different about the  

>>> KK 6502 (Atari) NOP adapter that makes it produce 8080 signatures  

>>> as opposed to the normal 6502 ones and I discovered that the  

>>> question has been posed before - not surprising I guess.

>>>

>>> Just wandering if this mystery was ever solved and perhaps I'm not  

>>> looking in the right places?

>>>

>>> I'm sure I once took down signatures from a working board using my  

>>> standard 6502 adapter but as always, when I want them, I'm damned  

>>> if I can find them so maybe I imagined it.

>>>

>>> In case anyone hasn't a clue what I'm talking about, see the  

>>> footnote on page 14 of the PDF document "SigAnalNotes.pdf" that  

>>> ought to be all over the net but I can't find a link to it just yet!

>>>

>>> The original TechTools list message where this was asked before is  

>>> here (with no answer):

>>> http://www.vectorlist.org/TechTools/2002/10/0035.html

>>>

>>> Thanks,

>>> Martin.

>>>

>> Check the FTP archive on TTL (link below) for "Sig-Analy- 

>> HPJMay77.pdf" this covers some Sig Analysis questions. I only have  

>> info on the 6502, 6800 and Z80 NOP fixtures, which is at the rear of  

>> "KK-Signature2.pdf" in the KurzKasch section of TTL.

>>

>> For your question I would print off the last two pages of the  

>> KK_Signature2.pdf, then pull up info on the 8080, find out what  

>> instruction gives NOP, and then compare the pinout with the 6502.

>>

>> John :-#)#

>>

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