Alan, 
Most pc's more than a couple years old with ide/pata drives have spare cable connections to add a second drive to a desktop or tower pc.  There are usually also 3 options for the drive  jumpers - master (MA), slave (SL) and cable select (CS).  The cables provided may say 'primary/master' or 'secondary/slave' , printed on the cable near the connectors.  Those work in conjunction with the CS jumper setting.  If the cables are not marked, then the master and slave settings should work.
Have you tried adding either drive to one of your existing pc's to see if it is recognized or if it is formatted?  I would try that first before working on the external connectivity.
Paul Hachmeyer  

-----Original Message-----
From: Personal Computer Hardware discussion List [mailto:[log in to unmask]] On Behalf Of alan smith
Sent: Tuesday, April 26, 2011 4:21 PM
To: [log in to unmask]
Subject: [PCBUILD] external drives

Thank you for your replies. The IBM desktop & tower have built in drives. The ones I'm trying to get working are 3:5 " IDE drives. I have tried them as masters and slaves. In R click my comp, >manage> disk management> one of the external drives ( with external power ) will show up but will not let me format. I've tried control panel > add hardware - nothing. The other doesn't show up anywhere. I'll try what you suggest tonight Peter & hope. Thanks again, Al

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                         PCBUILD's List Owners:
                      Bob Wright<[log in to unmask]>
                        Mark Rode<[log in to unmask]>