Re: DRAM chip spacing

On Tue, 22 Dec 2020 at 05:01, Jim Brain <brain_at_jbrain.com> wrote:
>
>
> > Thanks for the reply. I already knew 407 got different spacing. Maybe
> > someone can verify it's the only one.
> The 298 mobo appears to have slightly different spacing as well. It's
> the same width as the 425, but taller like the 407, but not exactly the
> same height (a bit taller, from what I can see)
> >
> > 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.
> That's true, but my goal was to create an adapter for my 2MB/8MB SRAM
> expansion, which needs the address and data pins arranged in the same
> way as the CPU, to allow the various MMU addresses and data values to
> make sense. As such, I needed D0 on the motherboard to be D0 in the
> SRAM module.
> > I used this to make the layout easier. I enabled pin swap function
> > between address pins and between data pins.
> Which is fine if you're just making a board with some SRAM on it. But, I
> was making an adapter, and I didn't want to assume anything about the
> module that will be plugged in.
> >
> > -Pasi
> >
> Jim Brain
> brain_at_jbrain.com
> www.jbrain.com

Thanks for the explanation. That makes sense.

-Pasi