Re: Apple II SRAM card

["Michael J. Mahon" <mjmahon@aol.com>]

PZ wrote:
> On May 10, 2:17 pm, Alex Freed <alex_n...@mirrow.com> wrote:
> > A2Aviator wrote:
> > > "The Engineering Dept." is actually the same group that produced the
> > > PC Transporter and Pocket Rocket, which is a 16K SRAM language card
> > > that AE offered. Although the AE offering has the LS245 on it, this
> > > one from Apple does not.
> > > The SRAM language card was made in order to outfit a large amount of ]
> > > [ Plus's that were being taken in from various school districts and
> > > being donated to other countries, so that they would have 64K in them.
> > This implies that the logic is identical to a regular 16K "language
> > card" so we already know it.
> > The trick is how to implement more memory with page switching that
> > existing programs can use.
> >
> > -Alex.
>
> I suppose that one would want to piece apart a Saturn 128k card or
> something of the like.

Exactly.

The Saturn 128KB card was the _de facto_ standard for RAM expansion
in the pre-//e days.  It used a bank register to simulate up to eight
16KB RAM cards.  It was controlled by accesses to the /DEVSEL space
at C0sx.  The .pdf manual is available online, but its security is set
to prohibit copying and pasting, or I'd include the relevant section
here.

-michael

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