Re: CIA old/new?

From: Segher Boessenkool <*segher_at_kernel.crashing.org*> Date: Thu, 7 Jan 2021 12:20:23 -0600 Message-ID: <20210107182023.GJ30983_at_gate.crashing.org> · segher_at_kernel.crashing.org

On Thu, Jan 07, 2021 at 07:12:33AM +0100, Gerrit Heitsch wrote:
> On 1/7/21 4:12 AM, Segher Boessenkool wrote:
> >>You shouldn't do that though.
> >
> >We only did it to show what causes the problem, yup.
> >
> >But would it even cause any problems?  You're only delaying #CS by 40ns
> >or so (if you do it right ;-) ), that's well within allowed timing, it
> >just avoids the annoying light-grey blips.
> 
> Yes, but you would also delay /CS for some ns over it going HIGH again. 
> Some other chip might want the databus at the same time.

The VIC also uses the R/#W signal for tristating the data bus drivers
(that and #CS, nothing else).  So this should be good still.

Nevertheless I agree that this is just asking for trouble :-)

Segher