himage@jolnet.ORPK.IL.US (Steve Schwartz) (09/30/89)
Has anyone out there ever installed, or heard of a way to install three floppy drives in an XT computer, two 5.25" drives, and one 3.5, 720k drive. If so, how can it be done, as far as I know, the XT can only accept two florry drives, or two floppy drives, and a tape drive on the floppy cntroller. send information to: himage@jolnet.ORPK.IL.US
perry@ccssrv.UUCP (Perry Hutchison) (10/06/89)
In article <1642@jolnet.ORPK.IL.US> himage@jolnet.ORPK.IL.US (Steve Schwartz) writes: > Has anyone out there ever installed, or heard of a way > to install three floppy drives in an XT computer, two > 5.25" drives, and one 3.5, 720k drive. > > If so, how can it be done, as far as I know, the XT can only > accept two florry drives, or two floppy drives, and a tape > drive on the floppy cntroller. As far as I know, an IBM XT uses the same floppy controller as the IBM PC, and that controller supports two internal drives plus one or two external drives. Each drive cable can handle a maximum of two floppy drives. (I don't know how the tape drive is connected -- that's something that got added on later, and not by IBM.) A four-floppy-drive controller allows for two drive cables. In the IBM PC (and I believe also the XT), the cable for the internal drive(s) connects to an edge connector on the controller card and the cable for the external drive(s) connects to a 37-pin D-connector on the controller's mounting bracket. Of course, some clones may have left off the external connector, but before giving up you might look for a second internal connector on the controller. This would be for a 34-pin ribbon cable. It might be either an edge connector (like IBM used for the internal drives) or a 34-pin header like that often used for hard disks. While we're on this subject, it is also possible to attach additional floppy drives to an AT. For an IBM AT, this is a bit more involved than for the XT since the AT's combined hard/floppy controller lacks the circuitry to support more than two floppy drives. Because of this misfeature, when the PC Convertible came out and IBM needed to allow for an external 3.5" drive, they had to design an adapter card (which takes up a slot!). It also connects into the ribbon cable between the controller and the internal floppy drives, and provides the missing circuitry and 37-pin external-drive connector. Some clone combination hard/floppy controllers have this done right: they include support for four floppy drives directly on the controller card.
klarich@a.cs.okstate.edu (Terry Klarich) (10/11/89)
If you are willing to build your own cable, you can have up to four floppies on a two floppy controller. I currently am using three on my AT. Just get a regular floppy cable with two edge connecters. Clamp on a third. Now the fun starts. You need to find the drive select (drive a or b) wire and strip it back from the cable. Run this wire through a switch to select which drive will be used at the moment. My set up is one 1.2 as "a" and 1 360 as b when the switch is in and 1 720 as b when the switch is out. I have been doing this for two years now and it works fine.