[Techtoolslist] Atari 6502A NOP adapter

[martin at guddler.co.uk]

Thanks for the info Tim.

I've made a new NOP adapter today that just uses a pair of LS393s as a  
16 bit counter as per the CAT box schematics and am now getting Atari  
signatures!

Martin.

On 25 Jan 2009, at 02:22, teeray wrote:


> 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 :-#)#

>>>