DD versus HD 5.25" floppy drives

You make an important, but IRRELEVANT point. I am cognizant of the differences, and the sloppiness of the terminology, and CHOSE to attempt to reply to the original poster using the terminology that he had used. I do have sample diskettes from hundreds of machines with 96tpi "DD" drives; unfortunately, unlike Don Maslin's collection, few are "boot" disks. http://www.xenosoft.com/fmts.html Every variant of the terminology that we have available for these systems still permits somebody to deliberately mininterpret what is being said, or make an honest misteak in interpretation, just by having been concentrating on some other part of the elephant. OK, YOU explain to the original poster why he will or will not have problems writing Kaypro2, Apple2, Commodore diskettes using the "1.2M" drive from an IBM 5170. He will need to know about coercivity, LATER, when he selects blank media to use. But, right now, for selesting which DRIVE to mount in the case, he does NOT need to be concerned with flux transition rate, disk total capacity, options of alternate physical formats, or variant exceptions to the "standard" formats. The issue for the original poster was whether he should use a "DD" drive or an "HD" drive. Those were HIS terms. HE was not referring with "DD drive" to a 96 track per inch 80 cylinder Modified Frequency Modulated 300 Revolutions per Minute 250,000 bits per second data transfer rate drive. It is too cumbersome to fully identify each drive type by its full set of specs, so we use shorter, albeit potentially ambiguous, terms. YES, "DD drive" can refer to several other things, but was it not possible, if one wanted to, to understand what he meant? We assume that what he meant what could [even MORE sloppily, but with less confusion] be called a "360K drive from a 5150" OR a "1.2M drive from a 5170", (along with a "1.4M" 3.5" drive). It does NOT add any clarity to point out that that first drive could be used for formats ranging from about 60K to about 440K - it is SIMPLER to refer to it by its most common usage (>99% of all of them!) for 360K. Is it really necessary to include 5150 and 5170 in those names? Apparently, YES - since although there was a 100 to 1 ratio of their usage, many here will tout their exceptions, as if they were the "norm". Likewise, it does not add any clarity to point out that it is ALSO possible to have 360K on a single sided 80 cylinder system. THOSE ARE IRRELEVANT to what the original poster is trying to find out. Although, YES, they are interesting and much more FUN variants. We could also do as NeXT did, and refer to the drive by its UNFORMATTED capaciy, if we wanted to further mislead. It is still subject to DELIBERATE misinterpretation, but anybody who WANTS to understand, knows what is meant by "360K" and "1.2M" drive. YES, I had 5170s with 100tpi single sided drives, 67.5 (V usual 135tpi) 40 track 3.5 inch drives, 3", 3.25", floptical, LS120, 1.2M 8" drives, 1.4M 3.4" drives interfaced serial (RS232), parallel ("Centronics"), "IDE", and SCSI. My first 5150 ended up with 2 "360K" (SA455) drives, a "720K 5.25" (55F), a "720K 3.5" (350), an 8" (848 external) and a "1.4M 3.5" (Microsolutions "Backpack" external). One of the 455s had the write protect jumper reversed, so that it could write no-nothch diskettes (for software duplication) but would default to write-protected for ordinatry "unprotected" diskettes. NONE of this paragraph of irrelevant crap helps the original poster, in any way shape or form, with his simple question of which of two drives he should mount in the enclosure. Another poster pointed out that the original poster had referred to his diskettes as FDDs, and asked how you copy a Floppy Disk Drive. Being from a "Fantasia" generation, I can't help but visualize Mickey Mouse as The Sorcerer's Apprentice. When it came time to move out of my office, I had to sweep up LOTS of FDDs that had multiplied. I was going to say "tons", but that might not be accurate - a metric buttload. -- Grumpy Ol' Fred cisin at xenosoft.com