From: kr-lund@nogarbage.online.no   
      
   Larry wrote:   
   > "pollard"  wrote in message   
   > news:1233ncsd28flve3@corp.supernews.com...   
   >   
   >>Hi all,   
   >>   
   >>I've got an old Teac 3.5" drive (in 5.25" mount) with jumpers set as Drive   
   >>1 that I want to install in my Model 4P. Tried to tackle installing it   
   >>today, but was unsuccessful. The 4P's drive cable is card edge only, so   
   >>tried using a PC drive cable hooking up the original 5.25 drive and 3.5   
   >>drive using both the cable's end and middle jacks. The 4P wouldn't   
   >>recognize either drive in any position.   
   >>   
   >>Anyone know what I'm doing wrong? Maybe it's due to the wire twist found   
   >>on PC floppy cables? I'm about at my wits end trying to find a way to   
   >>transfer DSK files from PC to 4P.   
   >>   
   >>Thanks,   
   >>   
   >>David   
   >   
   >   
   > To work with the TRS-80, the floppy drive has to meet a few conditions.   
   >   
   > 1. It has to have jumpers to change some functions   
   >   
   > The two jumpers you have to have are DS and RDY.  DS selectes between   
   > different drives. If you are only using it as drive :1, then you don't need   
   > to change this jumper.   
   >   
   > The RDY jumper has to be changed. In the IBM PC, this jumper's alternate   
   > position was used as a media change indicator. In the TRS-80 it is a ready   
   > indicator.  This is not an option.  If your drive does not have jumpers but   
   > has them all soldered in place, you're probably out of luck.   
   >   
   > There are some Teac floppy drives with jumpers. Since you state it is "old",   
   > it may be so equipped.   
   >   
   > 2. You have to have a straight-through cable   
   > The twist changes lines that the TRS-80 doesn't like. I don't remeber the   
   > details, but I do know it doesn't work for me.  Here you have some options.   
   >   
   > You can build a new cable from scratch; the parts can be found on the web   
   > with some searching in Google.  You can add a female IDC connector to your   
   > existing cable.  Crimping can be done with a vise with care, or a crimp tool   
   > if you don't have a vise.  These connectors are usually less than a buck.   
   >   
   > If you have a PC floppy cable with both card edge and IDC connectors, you   
   > can use the two before the twist.  The other end will plug into the 4P mobo.   
   >   
   > If you build a straight-through cable, you must change the DS jumper on your   
   > 5.25" drive to be the lowest number (DS0 or DS1 depending on the drive).   
   >   
   > I have a 4P with 2 3.5" Chinon drives.  I also modified it to use external   
   > drives, and have a case with one 5.25 and one 3.5" drive, each selected as   
   > drive 2. I then plug in whichever I want as my third drive (I like this   
   > better than making them both active, since I also have a Model I and with DS   
   > drives, I can only have three active).   
   >   
   > Larry   
   >   
   >   
   Hi   
      
   IMO you can ignore the RDY jumper:   
      
   None of the model I, III or 4 use the ready/insert signal. Line 34 is   
   not connected. Even 3rd party III/4 floppy cards are like this. I don't   
   know the 4P or have schematics for it so I now start wondering if it is   
   different. Is it?   
      
   Actually on the older EI for the model I this is not entirely true as   
   line 34 is connected to line 32 and the DS3/side select output signal.   
   This can be ignored as long as DS3/side select is not in use, because   
   the signals are wired-or type (won't really conflict). If there is a   
   twosided drive or a :3 then these lines should not connect. I would (it   
   is what I did) break the link on the card in the EI, it can even be done   
   without opening the EI, because no drive would use 34 as input for this,   
   not even old ones. If you don't want to modify the EI (even if you are   
   using it with modern drives) then pull the pin for line 34 when making   
   the cable or just cut the line in your cable.   
      
   Note that III/4 external :2 and :3 dives are using DS0 and DS1 respectively.   
      
   Sorry for the delayed response, I had to check my facts first.   
      
   When I scavenge I look for 3.5" drives that have jumpers or switches for   
   drive select, some modern drives have these tiny 0ohm resistors that can   
   be moved with a soldering iron. Actually just checked a Panasonic   
   JU-256A317P, two screws to get at the card and on the card is a field   
   R41/R42 where breaking the R42 link and soldering a 0ohm (lead) in for   
   R41 will make the drive :0. Tested it too, it works very well on one of   
   my model I's, unmodified, as :1. I'm maybe going to make a better   
   enclosure for the model I drives and wonder if it would be nice to use a   
   drive without the front...   
      
   Knut   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)