[Techtoolslist] 6502 NOP, or Clock divider

[Kevin Moore]

I just went ahead and built a clock divider out of 1 74s74 connecting the
clock from a normal 6502 nop, into pin 3, then feeding not q pin 6 into d
pin 2. and using q pin 5 as my new clock. It get's atari sigs now, and if I
need to just use normal 5004a sigs, I can just pull the clock divider.

Kevin


On Thu, Jun 17, 2010 at 3:36 AM, Martin White <martin at guddler.co.uk> wrote:


>

> > A NOP can easily be built by using a 6502 CPU and bending the data lines

> up over the top, then hardwire them to NOP and disable any watchdog reset,

> then plug the modified CPU into the board and power it up!

>

> That won't give catbox signatures on the 5004 though.

>

> It was me that posted about it I think. When I built mine I just used the

> schematics for the catbox. I'm sure Andy Welburn built one as well and I

> think he made his slightly differently? Maybe he wrote up some schems?

>

> > I have a picture up on TTL FTP of several modified CPUs and an Eprom

> (can't remember using that - might work), also a PDF of an article written

> back in the 70s about making your own...both of these are files starting

> with "NOP".

> >

> > John :-#)#

>

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