Re: Apple //c w/DuoDisk ?'s

[dempson@actrix.gen.nz (David Empson)]

stephen e buggie <buggie@ben07.unm.edu> wrote:

> I'm shooting from the hip here --- but wouldn't it be interesting to
> unplug the INTERNAL 5.25 drive from its IDE-20 connector, and to connect
> an IDE-20 adapted Duodisk into that drive slot?   Would both drives of the
> DuoDisk then become recognized?

Not without some hardware hacks.

The first problem is that the IIc only provides one of the drive select
signals on the D-19 connector.  You would need to arrange for the other
one (which goes to the internal drive) to be presented on the
appropriate pin.

The second problem is that the IIc redefines the pin in question and
uses it for an "external interrupt".  I doubt this has ever been used by
a real device, but if you didn't disconnect this signal when modifying
the motherboard you might be causing interrupts on changes of state of
the second drive select line.  Not a particularly good idea.

The third problem is that your drives would be backwards - drive 1 would
be the one on the right, and a single external 5.25" drive would be
drive 2.  This could be solved by doing another mod to swap over the
drive select lines going to the connector.

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand