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| From: Bionic (all posts)
Date: 2000-08-07
Subject: Re: Plus 4 Database Update
|
> > > Yes it's slightly more restrictive than the Hannes expansion, but *a lot*
> > > easier to build and I'd like to convert as many 256K programs to use it as
> > > possible, (a) to show its usefulness as a 256K expansion and (b) to make
> > > it easier for less technical users to build 256K machines.
> >
> > Where is the point ? The simple version of Hannes expansion is the most
> > supported 256kb extension. Its not more complex than your version.
> > (You are using a 6529, ls138 and two ls257 ?)
>
> Not quite, but a similar level of complexity. Do you have details of this
uhm well.. swap one ls257 for a ls153 :)
> very simple Hannes expansion? I don't think I've ever seen a diagram of a
> circuit that simple. The ones I have seen have been far more complex.
The basic extension maps bank 3 to $0000-$1000 or to $0000-$4000 (choosable with one bit) and bank 0-3 into the space above this. Thats it.
There is another slight extension to redirect all TED DMAs to bank 3 when a bit is set.
> The reason I developed this alternative expansion is that I was already
> developing one for the C64 and C128 and it uses the same principle, so I
> can re-use the hardware between the machines. If it really is as simple as
> the simplest Hannes expansion then I will of course abandon development
> and build a Hannes 256K plus/4 instead.
Probably the better choice. Getting software support for a new plus/4
256kb extension is nowadays a bit difficult :)
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