360K in a 1.2M drive (was: Parallel port hard drives?

There are TWO problems. The disk matters. The drive matters. 360K is 300 Oerstedt. 1.2M is 600 Oerstedt. Using the wrong coercivity of diskette, you will NEVER get a good, reliable result. You MIGHT sometimes almost get away with using the worng diskette. SOME idiots will claim that they "always use the wrong diskette". WHY??? BTW, 720K and 1.4M are nominally 600 Oerstedt and 750 Oerstedt, which is close enough that "getting away with" is a MUCH more likely proposition. There are several problems with using the wrong drive. But some times there isn't an adequate alternative. Read/write currrent level: With the exception of some of the preproduction Mitsubishi 4854 and prototype Shugart 475s, all of the 1.2M drives have explicit provision for TWO read/write current levels, explicitly for the purpose of permitting reading, and even writing, 360K diskettes in the 1.2M drives. That is typically NOT where the problem arises. Motor speed: 8" is at 360RPM; 1.2M is at 360RPM 360K is at 300RPM To do 360K in a 1.2M drive typically requires that the controller compensate for the different motor speed by running the 360K data transfer rate at 300Kbps instead of the usual 250K bps. PC controllers can normally handle that. Hooking a 1.2M drive to a non-PC controller that expects an 8" drive will not provide for that, and therefore will not work right for trying to do 360K diskettes. Many current drives have dual spindle speeds (300, 360) Weltec once made a 180RPM drive that would permit a PC 360K controller to do 1.2M diskettes! (reliability was less than ideal) THAT is typically not where the problem lies. Track width: Track width is a problem. Not only with 1.2m drives and 360K diskettes, but also even with 720K/800K 5.25" drives (Shugart 465, Tandon TM100-4, etc.) with 360K disk formats. 360K is about 1/2 mm per track, and the actual track itself is about 1/3mm wide. 1.2M, 720K 5.25", etc. is about 1/4mm per track, and the actual track itself is about 1/6mm wide. When working with a virgin, bulk-erased 300 Oerstedt diskette, the 1.2m (or 720K 5.25") drive CAN produce a diskette using every other track, that is ALMOST acceptable. It will have tracks that are only 1/6mm wide, but properly spaced at 1/2mm increments. You normally CAN get away with that, unless/until: if you EVER write to THAT diskette with a 360K drive, even "just erasing a file", you will have replaced that 1/6mm wide sector with a 1/3mm wide sector. From that point on, the diskette should NOT ever be written to with the 1.2m drive, unless/until it has been bulk-erased and formatted again. A 96TPI drive can NOT do an acceptable job of REformatting or REwriting over a 1/3mm wide track! Some people, using SOME drives have found that it is ALMOST good enough, and can sometimes get away with it. But that's like trying to use MY car at 100 mph. It just isn't built to do it RIGHT. Therefore, it IS possible to do an emergency transfer diskette from 1.2M to 360K, using a 300 Oerstedt diskette. But repeated back and forth requires careful attention to detail to avoid ever trying to rewrite a 1/3mm wide track with the 1.2M drive. -- Grumpy Ol' Fred cisin(a)xenosoft.com