ludwig@xybion.UUCP (ludwig) (12/15/89)
Gentlemen (and ladies...) I've got a friend looking over my shoulder here and he is interested in setting up an A/B type of switch to determine which of two floppy disk controller controlled devices he is going to use. He has a machine with a 3.5, a 5 1/4, and a tape backup system all controlled by said floppy controller. We've been toying with the idea of using an a/b switch along the floppy cable but have absolutely no idea which of the many little wires we need to connect to the switch. Any ideas? Also, if you've got a better idea as to how we can do this, please let me know. Reply by e-mail or post here if you think that the world has a right to know. Thanx in advance. Mitch
blitter@ele.tue.nl (Paul Derks) (12/19/89)
In article <101@xybion.UUCP> ludwig@xybion.UUCP (ludwig) writes: > >Gentlemen (and ladies...) > >I've got a friend looking over my shoulder here and he is interested in >setting up an A/B type of switch to determine which of two floppy disk >controller controlled devices he is going to use. He has a machine with a >3.5, a 5 1/4, and a tape backup system all controlled by said floppy >controller. > >We've been toying with the idea of using an a/b switch along the floppy >cable but have absolutely no idea which of the many little wires we need >to connect to the switch. Any ideas? > >Also, if you've got a better idea as to how we can do this, please let me >know. Reply by e-mail or post here if you think that the world has a right >to know. > > Thanx in advance. > > Mitch This is very simple: each drive has four jumpers on it, determining which drive is which. These jumpers are mostly numbered 0 to 3 or 1 to 4. But connectors on the jumpers of the two drives between you want to switch and connect these to a double switch. (I don't know the correct english name for this) Connect them in such a way that in one position the first jumper is short circuited and in the other position the jumper one the other drive is short circuited. Now the only problem you have is the really imbecile twisted floppy cable which IBM invented. I guess they can't read Shugart specs at IBM. This means that the physical position on the cable determines if a drive is A: or B:. It is therefore very important to determin which drive you want switchable. If you want A: switchable then you must use the part of the cable after the twist and isf you want B: switchable you must use the straight part of the cable. Good luck. Paul Derks