miker@csupwb.colostate.edu (Mike Riley) (02/05/89)
There was an ad in this February's Byte magazine, on p30 that really caught
my attention. To summarize, the company advertizing claimed that they had
a product that would allow you to format 720K disks to 1.44M, reliably.
The claimed that the media used in both disk types was exactly the same,
and that the only reason you couldn't format your 720K disk to 1.44M was
that the plastic casing was not suitable.
Is there anybody out there on the net that can confirm this? Is is
snake-oil salesmanship, or are the disk manufacturers/marketers ripping
us off? Is it at all possible that there's any middle ground? Enquiring
minds (and disk purchasers) want to know!
_________________________________________________________
|Mike Riley Internet: miker@csupwb.ucc.colostate.edu |
| Bitnet: miker@csugreen.bitnet |johnl@ima.ima.isc.com (John R. Levine) (02/06/89)
In article <1140@ccncsu.ColoState.EDU> miker@csupwb.colostate.edu (Mike Riley) writes: >[People claim that 720K and 1.44M floppies are really the same.] The oxide on 720K disks and 1.44M disks really is different. That said, I find that more often than not I can format 720K disks as 1.44M and they work perfectly well. I don't keep anything I really care about on those disks, since the chance of losing the data is somewhat higher than otherwise. The gizmo advertised in Byte and other magazines is really just a hole punch. There is a hole in the corner of real 1.44M disks so that the drive can tell what kind of disk it is. On most 1.44M drives (other than IBM's) it won't let you treat a disk without the hole as 1.44M. I'm sure that the hole punch works, but I'm not putting my important backups on disks run so far out of spec. -- John R. Levine, Segue Software, POB 349, Cambridge MA 02238, +1 617 492 3869 { bbn | spdcc | decvax | harvard | yale }!ima!johnl, Levine@YALE.something You're never too old to have a happy childhood.
akm@uoregon.uoregon.edu (Anant Kartik Mithal) (02/06/89)
I've been setting up a NEC PowerMate Portable that takes 1.44 MB disks. I had a bunch of disks from the owner to format, which I did, and got 1.44 MB disks. I now find that they are in fact only 720 K, and they had no problems getting formatted. Years ago, I used to format 5.25" SSDD as DSDD (180K as 360K) without any difficulty. If you are interested, I've been using Sonly and 3M disks.
tim@j.cc.purdue.edu (Timothy Lange) (02/06/89)
Important! Data loss can occur! High density disks have a different chemical makeup than double density disks. High density disks use a Chromium oxide, double density uses an Iron oxide coating. Other than that the 3.5" disks are the same (the high also has more sectors per track). As for the 5.25" disks there are more differences. Formatting double density disks at high density is risky business, data loss will occur over time due to a mismatch in the recording frequency and the media composition. -- Timothy Lange / Purdue University Computing Center / Mathematical Sciences Bldg West Lafayette, IN 47907 / 317-494-1787 / tim@j.cc.purdue.edu / CIS 75410,525
jls@killer.DALLAS.TX.US (Jerome Schneider) (02/07/89)
Several have implied that using 720k disks as 1.44m "seems to work OK". I'm curious if this is the same "seems to work" used for SRB O-ring analysis, or can someone give a short technical explanation. I would think bit density per inch, number of tracks per side, single or double sides, special encoding schemes are the type of info that could lead to a more definitive answer. -- Jerome Schneider UUCP: killer!jls.DALLAS.TX.US (guest account) Aspen Technology Group Ft. Collins, CO Voice: (303) 484-8466
chasm@killer.DALLAS.TX.US (Charles Marslett) (02/07/89)
In article <1140@ccncsu.ColoState.EDU>, miker@csupwb.colostate.edu (Mike Riley) writes: > > There was an ad in this February's Byte magazine, on p30 that really caught > my attention. To summarize, the company advertizing claimed that they had > a product that would allow you to format 720K disks to 1.44M, reliably. > > The claimed that the media used in both disk types was exactly the same, > and that the only reason you couldn't format your 720K disk to 1.44M was > that the plastic casing was not suitable. The IBM PS/2 computers got a lot of flack for not even having a sensor for the extra notch (hole) -- so they cannot even tell which kind of diskette is installed (at least our early 60 and 50s cannot). I have formatted and used some 720K diskettes as 1.44M diskettes, and of 2 boxes of 10 each, perhaps 15 actually would format and operate the day I formatted them. On the other hand, none are functional today. I do not know exactly what the difference is, but don't put anything permanent on a 720 used as a 1.44! On the other hand, if you are just carrying stuff from one machine to another there seems to be no problem. Charles > _________________________________________________________ > |Mike Riley Internet: miker@csupwb.ucc.colostate.edu | > | Bitnet: miker@csugreen.bitnet | =========================================================================== Charles Marslett STB Systems, Inc. <== Apply all standard disclaimers Wordmark Systems <== No disclaimers required -- that's just me chasm@killer.dallas.tx.us
boyne@hplvli.HP.COM (Art Boyne) (02/08/89)
akm@uoregon.uoregon.edu (Anant Kartik Mithal) writes: > Years ago, I used to format 5.25" SSDD as DSDD (180K as 360K) without > any difficulty. NEVER do this!!!! After prolonged abuse like this, the floppy drive can be *destroyed*. Single-sided disks are usually burnished/polished only on the single recording side. The other side is rougher, causing wear hardening of the disk read/write head. Wear hardening is a phenomenon where the material of the head loses its magnetic properties, causing the effective read/write gap on the head to back away from the surface of the head. This increases the effective distance from the gap to the surface, lowering the signal levels and increasing the chance of error. Eventually, enough damage will be done that nothing can be reliably written or read. I learned this while working for the division of Hewlett-Packard that made 8" and 5.25" floppy drives, and the same thing applies to the 3.5" units. Art Boyne, boyne@hplvla.HP.COM