[Techtoolslist] Atari 6502A NOP adapter

[Colin Davies]

Its basicaly used to exercise the addresss bus on the board...(The cpu 
constantly runs the nop instruction which is hard wired - so it 'counts' 
through all memory locations).. By using a signature analyser on various 
lines on the board, is is possible to produce useful fault finding 
information....

For instance... if say A15 was faulty down stream from the cpu (maybe due to 
a driver IC or a short) - it would produce a differnt signature than a 
working board.... you could also test eproms and such to an extent...

Hope this helps.... I'm sure someone can provide a much better 
explanation.... Cheers, Colin


----- Original Message ----- 
From: "kevin spears" <micrologix1500 at yahoo.com>
To: <techtoolslist at flippers.com>
Sent: Thursday, February 05, 2009 8:16 PM
Subject: [Techtoolslist] Atari 6502A NOP adapter



> This is surely a dumb question, but what is the purpose of the NOP 

> adapter?

>

>

>

>

>

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