Re: DRAM chip spacing

On Sun, 20 Dec 2020 at 22:22, Jim Brain <brain_at_jbrain.com> wrote:
>
> On 12/20/2020 1:39 PM, Pasi Lassila wrote:
> > Is the 250407 the only one with narrower DRAM chip spacing?
> I think so.
> > I checked motherboard images from the web. By measuring from the
> > images it looks like it.
>
> You an get full measurements from this project:
>
> https://github.com/go4retro/DRAMCarrier
>
> > I only got 250407 & 250425 8 DRAM chip motherboards.
> > I made a new SRAM board which is designed for 466&469. It also works
> > in older models by changing two resistor positions and soldering 6
> > extra wires. With flat pins it also fits 407 if the pins are bent
> > slightly and sockets are leaf spring style.
> > https://i.imgur.com/dzmaocY.jpg <https://i.imgur.com/dzmaocY.jpg>
> >
> > -Pasi
>
>
> --
> Jim Brain
> brain_at_jbrain.com
> www.jbrain.com

Thanks for the reply. I already knew 407 got different spacing. Maybe
someone can verify it's the only one.

I checked your Github project.
What do you mean by "Care has been taken to preserve the relative
order, so D0 on the 4164 and D0 on the 4464 should be the same."?
You can mix address pins together and data pins together and the
memory works the same. Some SRAM/DRAM datasheets don't even number the
address or data pins.
I used this to make the layout easier. I enabled pin swap function
between address pins and between data pins.

-Pasi