Re: Slowest IIgs RAM

[exegete@nunya.biz]

Quadrajet1 wrote:

>  > : Does anyone know what the slowest speed 256K DRAMs that can be
>
> > : > used in
> > : > : the IIgs one meg memory card would be? If memory serves a 1 mhz
> > : > 6502
> > : > : needs at least 400 nanosecond chips, so I would assume 200
> > : > nanosecond
> > : > : chips would be a bit too slow for the card. Am I correct?
> > : > :
> > : > : Roy
> > : >
> > : > 200ns is FASTER than 400ns.
> > :
> > : Absolutely correct, and totally worthless.
> > :
> > : I would have been more accurate if I weren't ill and under the effects
> > : of prescribed narcotics. What's your excuse?
> >
> >
> > > Hey, no need to cop an attitude. I really thought you didn't
> > > know.
> > > My statement was not meant to be taken the way you apparently
> > > did,
> > > so, I shall not speak at you again. Sorry, very sorry.
> >
> > Ok Bill. Let's assume that you have just told us the truth here. In that 
> > case, please note that you have corrected my 
> > misstatement/misunderstanding about 200 vs 400 nanosecond rating of the 
> > chips. So, why did you not saying anything about what I really needed to 
> > know? Is/Are (I'm still suffering from diminished mental ability due to 
> > illness and meds) 200 nanosecond chips fast enough for the IIgs?
>
>
>  Maybe you need to study a bit.  The speed rating of the chips is the maximum
> access rate. The 200ns chips can be accessed or addressed at 200ns intervals,
> or every 200ns. 200ns is twice as fast as 400ns.  The ns is nano Seconds, which
> is a measurement of time.  100ns is 4 times as fast as 400ns.  So if you have
> determined that 400ns chips are fast enough, 

Ray, 400ns is fast enough for a 1 mhz 6502. How fast do I need for a 
2.8mhz 65816? That's my question. At this point it's all academic, since 
I used 80ns chips. When I had asked the question I was going to use 200 
ns chips if I could have gotten some help.

Thanks.

Roy

then the 200ns chips are overkill,
> since they can be accessed twice as fast as you need.
>
>   Let's say they made a 600ns chip, and you tried to put it in your IIgs.  It
> wouldn't work, because the CPU would be trying to access the chip every 400ns,
> and the chip can only be accessed every 600ns.  It's can't handle it.
>
>   Obviously, they never made a 400mns chip, and the majority of the ones you'll
> find are 70 or 80ns chips.  
>
>   It's late, and I want to get up early and ride my motorcycle out to the Hill
> Country tomorrow.
>
> Raymond



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