On 04/15/2015 1:15 PM, teeray wrote:

I know how to make one of these that will give Address bus signatures that match the Z80 sigs and will match all of the Atari documentation sigs but I would like to know the real opcode that Kurz-Kasch used for this NOP (data bus wiring)

If you can help please let me know.

Thanks Tim

NOP codes are specific to each CPU, usually the are something like 00h or whatever. I'm including a photo I took of my home-made NOPs for a few common CPUs - these just plug into the CPU socket in place of the original and work like a charm. Note that I have sometimes lifted the Reset pin and tied it to a mini pullup & cap as needed. Can't find the original article from Canadian Coin Box that these were derived form (not scanned it seems), and apparently KK was annoyed that CCB published the article, however there was no secret about NOPs as the technical sheets on each CPU told you the code needed. John :-#)# -- How to subscribe or unsubscribe from TTL http://seven.pairlist.net/mailman/listinfo/techtoolslist