Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!hplabs!hp-sdd!megatek!zeta!hollen From: hollen@zeta.megatek.uucp (Dion Hollenbeck) Newsgroups: comp.sys.ibm.pc Subject: Re: External 3 1/2" Floppy Message-ID: <587@megatek.UUCP> Date: 21 Jun 89 16:22:37 GMT References: <3007@csd4.milw.wisc.edu> Sender: news@megatek.UUCP Distribution: na Lines: 90 From article <3007@csd4.milw.wisc.edu>, by burkett@csd4.milw.wisc.edu (Edward W Burkett): > I have a Leading Edge Model D with the following installed: > > 640 K > 2400 baud modem > 5 1/4 in. floppy > 30 meg Seagate HD > DOS 3.2 > > What I would like to do is add an EXTERNAL 3 1/2 in. drive. > The question is HOW? > > 1) The LE only has two connectors on the power supply. > 1 - for the HD > 1 - for the 3 1/4 in floppy > > 2) The LE has the floppy controller built into the mother board. > Will that controller work or do I need another? > > I would like info on what I need to know to do this. > Any help would be appreciated. Here are some things you can do, but with some cautions. You can do these IFF: 1) Your power supply has enough wattage to handle an extra drive (has nothing to do with number of connectors). 2) Your BIOS does not disallow flopy drive numbers beyond 0. 3) Your floppy controller does not disallow floppy drive numbers beyond 0. 4) If the model D is an XT style, if you can set the config switches for 2 floppies, or if AT, you cna run setup and it will let you tell it you have 2 floppies. If your internal power supply has enough power for two floppies, merely buy a "Y" connector and draw power for both floppies from the same connector which supplied it to the first one. Make a 5 wire extension for the external one with #12 wire to go out of the cabinet (#12 to ensure not too much power loss through resistance). If your power supply is small or marginal, you can but external floppy cabinets with built in power suppplies to supply the floppy without using the internal power supply. Now that you have power, you need to get the drive control signals out to the external drive. This requires a 34 pin flat cable, similar to the one which currently goes to your first floppy drive. There are two ways to cable two drives. 1) Cable is straight through to both drives and drive A is jumpered as drive select 0 (small jumper block near ribbon cable connector). 2) Cable is twisted (drive select, motor enable) the twisted part going to the A: drive and the straight part going to the B: drive. Both drives are jumpered as drive 1. The preferred way is number 2. The reason is that for some reason, flopy drives do not answer up too well when jumpered as drive 0. By making them both drive 1 and twisting the cable, you have fooled drive A: into answering up to drive select 0. You can find out how to twist the cable by looking inside any standard PC with two floppies. The cable could be made in any manner, but I suggest that the best would be to put the appropriate 34pin connector for your motherboard in the center with the twisted side of the cable being short and going to your internal floppy and the long side snaking out between the case and out to the external drive. Some people may mention about radiated emissions, and I realize that with unshielded ribbon cable, this may be a problem. There are two solutions. 1) Do a whole lot of soldering and create a cable which uses round shielded cable to be the extension for the external drive. 2) Wrap the whole flat cable in several thick layers of aluminum foil. (I suggest this unless you love to solder). Hope this helps. I have done this for a numbe of years. I currently have a PC with 4 drives, 2 internal and 2 external, both working off the same floppy card and an AT with one internal and one external drive on the same card. I'm real pissed off that whoever conceived the AT style setup program decided that you could not be allowed more than 2 floppies. Even though my controller card is set up for 4 drives, the BIOS will not recognize more than 2. BTW, anybody know of a BIOS which will recognize 4 floppies? Dion Hollenbeck (619) 455-5590 x2814 Megatek Corporation, 9645 Scranton Road, San Diego, CA 92121 seismo!s3sun!megatek!hollen ames!scubed/