[cctalk] Re: Running DOS executables on other versions of DOSRe: Looking for Sharp PC-5000 disk drive (CE-510F or possibly MZ-80B)

Fascinating notes! I did run into oddities when using a 360KB disks in between a 1.2M 5.25 drive on the '386 and the 5.25 drive on the Sharp PC-5000. I forget my exact sequence of events, but in short the MS-DOS 2.00 FORMAT.COM on the Sharp PC-5000 would start marking a few bad sectors (sometimes just a few KB, sometimes as much as 20KB of bad sectors). And yet those same disks were formatted as just fine and no bad sectors over the '386. Or, if I used IMD and wrote full MS-DOS 2.00 image to the disk, then the disk would work (and boot) fine in the Sharp PC-5000. Without nit-picking the specifics here (of whatever I did) - my lesson was there is definitely a difference between a completely uninitialized disks, versus something that has been previously formatted. Which, yeah, duh - but my real lesson was: you can't always FORMAT.COM your way back into a bootable disk. If something else has "touched" the boot sectors, then another system might start flagging those as bad sectors. I'm not sure if IMD (ImageDisk) trumps all that? Meaning, whatever crap is on the disk, does IMD not care? In otherwords, is using IMD kinda-sorta like degaussing (and then applying whatever the image is)? It just seemed to me that however I mangled the format on a disk, IMD was always able to get me back into a usable (and bootable) disk. I do remember (vaguely for me) in the 80s we'd get boxes of uninitialized disks, and there were generally warnings along the lines of once it was formatted to whatever system you intended to use the disk for, it was thereafter basically committed to being used for that system. (but it seems only because, back in those days we didn't typically have the benefit of something like IMD software or a Greazeweasal - and I imagine the documentation from disk vendors didn't want to get into the weeds of waving magnets around your disk, especially when they already had bold warnings of keeping your disk the heck away from any magnets :) ) Regarding the article on SF rail replacing disk drives, to avoid "catastrophic failure".... recall a while back, ActionRetro made a RAID out of floppy disk drives (3.5"'s). With all the firmware going into modern SSD's and M.2's, I ponder the irony of "old dumb mechanical drives" actually being (in a way) more secure. -Steve On Tue, Oct 29, 2024 at 8:35 PM Fred Cisin via cctalk <cctalk(a)classiccmp.org> wrote: > On Tue, 29 Oct 2024, Chuck Guzis via cctalk wrote: >> The location of track 0 is radically different in the 96 tpi and 100 tpi >> conventions--there's about a 6 track offset. 100 tpi drives were also >> spec-ed as being 77 track (like their 8" relatives). > Are the tracks offset from one side of a disk to the other? > >