Re: Apple II disk drives and controller cards

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

In article <3a47gr$bja@tribune.usask.ca>,
A.J. (Tony) Allen <allent@duke.usask.ca> wrote:
> Our school district has hundreds of Apple IIe computers, with older 
> (black front) disk drives that are wearing out.  Does anyone know if a cable 
> adapter can be built that would allow us to use newer (beige or
> platinum) drives with the older-style controller cards?

Yes, it is possible.  In fact, Alltech Electronics probably sells
cables of this type.

Open-Apple magazine (now A2-Central) published a diagram of it back in
1985.  Their diagram showed the cable required to adapt a Disk ][
controller card to connect one or two UniDisk 5.25 drives (which is
exactly what you want).

Simple adjustments to the layout and connectors can be used to make
other connections, e.g. plugging a Disk ][ into a DB-19 connector,
such as a UniDisk 5.25 card.  You can even daisy-chain a Disk ][ from
the back of a UniDisk.

The main restriction is that you can only have two 5.25" drives on
each controller, no matter what type they are.

> There may be complications, however, since the newer drives are
> designed to be daisy-chained, whereas the old controller cards will  
> handle just 2 drives, each with it's own cable connector.

No complication there - you can either make up two adaptors, one for
each drive connector, or make up a combined adaptor which allows you
to daisy-chain two UniDisk 5.25 drives.  A single wire connection is
needed to the second drive connector on the card.


Actually describing the cable is a little tricky, and it is not
something I would recommend anyone making up unless they are VERY sure
that they know what they are doing.  If you make any mistakes, you
could easily damage your disk drive and/or controller card.

If anyone wants information on the connector and cable pinouts, send
me some E-Mail.  I'll have to dig up the last copy I typed in.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand