miken@hcr.UUCP (11/06/87)
ssfln (small snack for line eater) Today, whilst perusing books at my favourite computer bookstore (Computer Book and Supply Centre Ltd. 1263 Bay Street, Toronto) I saw with my very own eyes the mythical HD 3.5" disks, at only $99.95 for a box of 10, and the salesman kindly informed me that they were for PS/2 (MOM! he said THAT word!), and require special hardware. Gosh Batsman, the thought of 2Mbytes on a 3.5 makes me drool, so my question is... Does anybody out there in netland know anything about these little wonders, aforementioned hardware, and most importantly, how I can make my ST use these disks? is this a forlorn hope? am I doomed to insufficient storage for the rest of time ? (please don't suggest I get a hard disk. i am supposed to being doing real work right now, so I don't have time for an extended flame on bizarre interfaces, outrageous costs, and laughable reliabilty. until write-and-read-as-many-times-as-you-bloody-well-want optical disks come along (and they will! RSN), I'd prefer to stay as far away as I can from those aggravation-crates) Mike Nemeth #include <disclaimer.h> uucp: ...utzoo!hcr!miken "You are what you know." James Burke
dclemans@mntgfx.mentor.com (Dave Clemans) (11/11/87)
The difference between the current ST floppies and the 2 megabyte
ones is similar to the difference between the floppies on an
IBM PC-XT and a IBM PC-AT. Basically the clock rate is doubled,
letting you pack in twice as much information.
The consensus among the hardware people I've talked to is that
the WD 1772 that's currently in the ST can't handle a higher
clock rate. However if you removed the 1772 from the motherboard
and replaced it with a daughter board with appropriate clocks,
controllers, etc. you could get the hardware set up correctly.
The software incompatibilities you'd see would include:
the desktop disk formatter and copier probably wouldn't work
(but there are public domain versions of both of these available)
nothing knows about "switching" densities; i.e. you'd have to
invent some way to dynamically change clock rates
dgcschuster@dasys1.UUCP (Michael Schuster) (11/11/87)
In article <2923@hcr.UUCP> miken@hcr.UUCP writes: > >Does anybody out there in netland know anything about these little wonders, >aforementioned hardware, and most importantly, how I can make my ST >use these disks? These diskettes write 80 tracks x 18 sectors/track. They require a special drive mechanism whose write bias is adjusted by a special pin on the cardedge. Similar to the way AT clones enable the 1.2MB 5.25" drives. A friend and I recently tried an external high density drive (made by NEC) designed for AT clones. It could read 720K diskettes but little else. It could not read 1.4 MB PS/2 diskettes at all. Probably the controller is incapable of recognizing this format - DiskMech said the tracks were blank. Perhaps these beasties could be run through a hard disk controller, like Supra's 10MB floppies. If not - I fear it may be hopeless. -- l\ /l' _ Mike Schuster {sun!hoptoad,cmcl2!phri}!dasys1!schuster l \/ lll/(_ Big Electric Cat schuster@dasys1.UUCP l lll\(_ New York, NY USA DELPHI,GEnie:MSCHUSTER CIS:70346,1745
cmcmanis%pepper@Sun.COM (Chuck McManis) (11/12/87)
The scoop on the high density drives is that they use a data clock that
is twice as fast as the low density drives. On Amiga/Atari/PC-XT type
5.25 and 3.5 inch disks this clock runs at 250Khz, on the AT and PS/2
this clock runs at 500Khz. Exactly double the speed, means you can fit
twice as many sectors on a track and double your storage (720K -> 1440K).
The standard Western Digital minifloppy only controllers will not read
or write this format. The WD1793 and family of dual 8"/5.25" controllers
will given they are supplied with the proper clock. Also, when you double
the bit rate you cram more bits in the same space so your drive mechanism
has to be able to resolve a higher number of flux changes/inch (fci) and
the diskette has to be capable of retaining those flux changes faithfully.
So all you need are a new controller, drive, and diskettes and you're all
set. No I don't if anyone is planning on offering them for the above
mentioned computers (except the AT and PS/2 of course).
--Chuck McManis
uucp: {anywhere}!sun!cmcmanis BIX: cmcmanis ARPAnet: cmcmanis@sun.com
These opinions are my own and no one elses, but you knew that didn't you.