[sci.electronics] Hard disk Ctrl Query!!!!!!

oliver@cup.portal.com (06/14/88)

I have an IBM AT clone....12Mhz 0 wait...and such...
I run SCO Xenix with 2-130 meg Priam drives.
What I want to do is add a third disk!!!!!
I have had no luck in locating a MFM 3+ drive controller!
I know there must be one avaible..or a way of configuring a second controller
to accept disks 2 and 3...
I want the third to be partioned DOS....

If there are no controllers avaible for 3+ how about this..
Cabeling 2 drive ones....i.e. same drive select/data/controll lines....
and have a 2 way toggle switch for the power between the drives?????
i.e. only one would recieve the 12,5 volts at once.....
Would this cause a problem with the operation of the other drive????

If so is there a way I could build a switch to connect the data/ctrl lines
between the drives.....Some sort of swichable buffer device?????

I do not know if some of the pins are bi-directional High speed......

Any help or schematics on my questions would be GREATLY APPRECIATED!!!!!!

Oliver@cup.portal.com

zeeff@b-tech.UUCP (Jon Zeeff) (06/16/88)

In article <6490@cup.portal.com> oliver@cup.portal.com writes:
>What I want to do is add a third disk!!!!! 
>I have had no luck in locating a MFM 3+ drive controller!
>
You can add a second hard disk controller to an AT.  Be sure it's a model that
has the jumpers to change the io address.  All you need then is a dos
device driver to use the second controller.  I have one mostly written that
I may never find time to finish.  I'll mail it to anyone interested in
completing it.  Has anyone seen a commercially available driver that uses
a second controller?

--Jon


-- 
Jon Zeeff           		Branch Technology,
uunet!umix!b-tech!zeeff  	zeeff%b-tech.uucp@umix.cc.umich.edu