Re: IIc Memory..

[mdj <mdj.mdj@gmail.com>]

On Feb 4, 5:01 pm, "Michael J. Mahon" <mjma...@aol.com> wrote:
> mdj wrote:
> > On Feb 4, 5:00 am, "Michael J. Mahon" <mjma...@aol.com> wrote:
>
> >>The Slinky design only provides efficient sequential access to the
> >>expansion memory, and is therefore best suited for RAM disks and
> >>certain "swapping"-style memory managers, like Appleworks uses.
>
> >>In fact, I've always theorized that the Slinky design was inspired
> >>by Appleworks, which was the premier Apple II app that could benefit
> >>from memory expansion.
>
> > It was also released early enough that there were a lot of ][/+
> > machines still in service, and without motherboard modification bank-
> > switched designs are limited to the language card area, not to mention
> > the complications with cooperating with existing slot-0 language
> > cards.
>
> Good point.
>
> But even bank switching a meg in 16KB banks would be just as fast and
> as easy as the Slinky architecture for sequential accesses, and it would
> be more versatile--just an extension of the Saturn scheme.
>
> But there wasn't much of a market for >128KB memory expansion pre-//e,
> because Appleworks was the primary "consumer" of expansion memory.
>
> Certainly there were some Pascal users who would have wanted a larger
> RAM disk, but they must have been a miniscule number compared to the
> Appleworks armies who craved a larger desktop.
>
> (I was one of those who might have been interested, since I used the
> Plusworks patches to run Appleworks on my ][+.  ;-)
>
> It's actually quite disappointing how little real use there is for
> expansion memory--another chicken and egg problem in the marketplace.
>
> And if today is any indication, there were a lot more third party
> RAMworks-style cards in use than Slinky-style expansions.

Well it was so simple - take the existing scheme and add a bank select
register :-)

> If there had been a new version of ProDOS that loved memory expansion,
> and tools to make it easy for applications to use, memory expansion
> might have been more useful and more popular.  Of course, a single
> architecture would also have helped.  ;-)

It is a pity - I guess by the time there was market demand for such a
thing there was also the Apple IIgs, and Apple seemed reticent to
provide genuine enhancements to ProDOS after the IIgs was released. I
suppose that's fair enough; at that point there were three Apple II
platforms to support + Mac so the commercial imperative would have
been to encourage obsolescence of the lower end.

> I'd vote for bank switching over Slinky in an instant.  For sequential
> block access, the bank-switched architecture is nearly as fast as the
> Slinky architecture, and bank switching also supports code execution
> and fast random accesses within a bank, which Slinky does not.

Absolutely! With clever application design you can exceed the
performance of Slinky cards by a considerable margin, since bank
switch replaces swapping, although you have to be a bit wasteful with
the memory to do so, but I can live with that. The tying together of
the LC and ZP areas in the IIe's bank switch architecture always
seemed like a painful compromise, and it's very difficult to use the
extra AUX language cards. That said, 700k of memory makes for a
*very* capacious 8 bit machine.

Matt