@* Is it possible to install an internal 3.5" floppy drive in a system that already has two other internal floppy disks? The internal connectors of the standard floppy disk controller only support two drives, but a way to re-route the external connection inside to the internal connector of the 3.5" drive was devised. This discussion took place on the IBMHW Forum of IBMNET on Compuserve; messages edited by Joan Friedman 76556,3643. @* Message no. range: 43373-45777 @* Date range: February 7-21, 1987 Fm: David Stager 71256,1560 07-Feb-87 To: Joan Friedman 76556,3643 I want to keep the two regular floppy drives already installed *and* add the 3.5" floppy but *don't* want to add another controller card, hence my idea to connect the 3.5" drive to the external bus connection if this is even possible. I am familiar with the Y connector you mentioned because I used one when I hooked up the hard disk. How would you (or anyone in the know who reads this) suggest installing the internal 3.5 floppy? I have the standard IBM floppy controller that came stock from Computerland in 1985. Does the standard floppy controller have the ability to control more than two drives? Perhaps I am just ignorant of my equipment's capabilities. Fm: Nelson Ford 71355,470 11-Feb-87 To: all I finally received my 3.5" drives. One of the machines I want to add a drive to is an old, plain vanilla IBM PC that presently has two full-height drives in it. I was planning on removing one of these drives and putting a half-height 5.25" and the 3.5" Toshiba in its place, but the installation kit that came with the Toshiba does not include conversion cables to allow three drives to be hooked up inside an old PC. Any advice would be appreciated. Fm: Clyde Washburn 70305,1211 11-Feb-87 To: Nelson Ford 71355,470 (X) The third drive must use the rear panel connector - it's wired for the third and fourth drives - the internal cable is wired for the first and second only. Get an Insulation Displacement Connector to fit the rear panel conn (a 37 pin male "D"), and put the flat cable in with the stripe at the pin 1 end BUT WITH THE FIRST THREE CONTACTS AT THE PIN ONE END OF THE CONNECTOR UNUSED (cable flush to BOTTOM end of connector). Set up the drive sockets just as they are on your "stock" IBM cable, and you're all set. Let me know if I missed anything. Fm: Nelson Ford 71355,470 11-Feb-87 To: Clyde Washburn 70305,1211 (X) I see this is not going to be a simple case of popping the drive into the machine. I can go to the corner drugstore and get an "Insulation Displacement Connector", right? Fm: Clyde Washburn 70305,1211 11-Feb-87 To: Nelson Ford 71355,470 Digi-Key should have them, the flat cable, and the edge connectors. Somebody have the phone # and/or the catalog #s handy? Fm: Joan Friedman 76556,3643 11-Feb-87 To: Clyde Washburn 70305,1211 (X) Digi-Key: 1-800-344-4539 If an "Insulation Displacement Connector" is the same thing as a "D-Subminiature Conector .... Utilizes Standard 28 ga IDC Cable", then a 37-pin male connector with gold contacts is part no. R603-ND, $9.22. With tin contacts N8603-ND, $7.29. Fm: Nelson Ford 71355,470 12-Feb-87 To: Clyde Washburn 70305,1211 (X) I called Digi-key and they weren't real helpful. Never seem to have heard of IBM PC's. Said I would need to buy a "very expensive" crimping tool. I'm surprised nobody sells these cables made up. Someone gave me a Jameco catalog and I saw a 2-from-1 power cable that will let me get power to the drive, but they didn't have the data cable made up. Fm: Clyde Washburn 70305,1211 12-Feb-87 To: Nelson Ford 71355,470 That's pretty disgusting! The magic tools required to do one or two at home are a bench vise, or other parallel-closing vise or press with enough jaw opening to get the connector in, plus another 1/2" or so. The second exotic tool is a paint stirrer, or old yardstick (hardwood preferable). Cut pieces to face the vice jaws, and on the back side of the connector note if clearance notches are needed for the end structure -- if it will stick out above the compressible part. Another way is to cut pieces of wood just as long as necessary for the back side, using different pieces for 25 pin, 37 pin, etc. The other side just prevents the tips of male pins from being dinged by the hard (or knurled) vice face. Slip in the cable, check that it rests straight in the connector grooves, and squeeze until the gap in the connector is closed. Done. I've never used the "correct" tools until after a product was designed and the tools for specific connectors and sizes were ordered for the Industrial Engineers, but it never stopped me from assembling a cable. BTW cutting the flat cable before inserting in the connector is best done with scissors, rather than "cutters", and after installation flush-cutting to the body is best done with a sharp xacto knife or single-edged razor blade. Inspect visually for wire strands long enough to short to the next wire when done. If this is a real problem, I could make up some cables, but I'd have to get the connectors, as I'm out of both at the moment. Fm: Stephen Satchell 72736,70 13-Feb-87 To: Clyde Washburn 70305,1211 You use a bench vise, I use a WorkMate that acts like a vise. Interesting how many of us use what we have to get the job done. Fm: Joe Kyle 76703,437 13-Feb-87 To: Stephen Satchell 72736,70 (X) I find that a drill press vise provides much smoother control when crimping IDCs of all sorts, and is also handy for holding solder pot DB25s when making custom RS232 cables. It is heavy enough to stay where you put it, even with a chunk of twelve conductor hanging off of the connector. Fm: Keith Uddenberg 70735,1530 16-Feb-87 To: Stephen Satchell 72736,70 I use a woodworker's vise, small size. Has nice flat wide jaws that are not hardened or knurled. Fm: David Stager 71256,1560 21-Feb-87 To: Clyde Washburn 70305,1211 I constructed a cable as you described in an earlier message to connect a 3.5" floppy via the 37 pin external connector. My question is: Do the first three unused pins provide any power to the floppy? I just can't get the motor to spin on my mini disk. The disk access light comes on but I'm sure the motor isn't spinning. I am wondering if my problem is in the cable. I guess what I'm saying is are you SURE that your description of the cable was correct, ie first three connections unused/34 wire ribbon cable flush to bottom etc.??? Fm: Clyde Washburn 70305,1211 21-Feb-87 To: David Stager 71256,1560 (X) It was correct in the original context -- using the rear panel connector for an _internal_ 3.5" drive. Power is normally not part of the defined floppy interface, but I believe it was Joan that noted someone has used those 3 extra wires for power, but they are _not_ connected to power inside the PC, so you must also do that, as well as connecting them to the power jack at the drive end of the cable. It's probably easier to add a "Y" connector to your internal drive power, and tape the wires to the external drive to the flat cable -- also flat cable conductors are a bit thin, if you have any distance involved. Fm: David Stager 71256,1560 21-Feb-87 To: Clyde Washburn 70305,1211 (X) The drive seems to be getting power. It has a separate power connector like any other drive. It is external only to the extent that it is connected to the external bus on the floppy controller, otherwise it's mounted internally. I used a three foot ribbon cable, is this too long, and/or could it cause the problem I have described? Again the problem is... the disk access light comes on when I try to format a disk in there, but the motor doesn't spin. Could this problem be caused by a bad cable from the 37-pin -> 34-pin cable or should I start looking into problems with the drive itself. It just occurred to me that the drive could be defective. Can a regular 5.25" floppy be run via the external bus? I am thinking that I might swap some wires around and see if the Toshiba works if I substitute it for regular drive B:. If this works, how do I get the 5.25" drive set up to run off the external bus? Any dip switches to change? (I have half-height CDC drives) Fm: Clyde Washburn 70305,1211 21-Feb-87 To: David Stager 71256,1560 Yes, putting a 5.25" drive known to be good on the new cable is a great way to check it. If you set the dip switches on your mother board for 3 drives, it should be 100% fuctional, just by addressing a command to C: (your hard disk would get moved up to D: with 3 floppies set on the switches). There are TWO lines that tell the drive to work: 1) Drive Select - that usually turns on the LED, and 2) Motor Enable - sounds like this one isn't getting turned on. Inspect the IDC connectors for good alignment of wire and contacts, or better yet use an ohmmeter to check continuity on each wire. Even though the numbers don't jibe, you can check by how far from the end, and on which side each paired contact is, i.e. starting at the end opposite the stripe, take the end contact on one row ow the "D" connector, and find the end contact on the 34 pin that it checks out to -- every other pin, in order, should match to the next, in order, on the other end; and ditto for the other row. Natch you'll have to account for the IBM twist on one connector. Even if you leave the switches at 2 drives, a 5.25" on the back connector should be fine if you use DRIVER.SYS to address it, and describe it correctly. Fm: David Stager 71256,1560 21-Feb-87 To: Clyde Washburn 70305,1211 (X) Sorry I panicked too soon. Your cable set up is right-on the money. My problem was solved by changing the switches in DRIVER.SYS. I discovered through trial and error that the correct switch is /D:3 when connecting it through the 37-pin bus. I want to thank you for your patience and for providing the pinout information. I never would have figured it out myself. Fm: Clyde Washburn 70305,1211 21-Feb-87 To: David Stager 71256,1560 Whether the drive is /d:2 or /d:3 depends on BOTH the setting of the DS jumper on the drive and whether your cable has an "IBM twist". You happen to have it addressed as the 4th drive, but that's fine as there's no value in consecutive drives if you address them thru device drivers anyway. Glad you're up and running now.