sac90286@uxa.cso.uiuc.edu (Kubla Khan) (08/23/89)
In article <1293@cbnewsd.ATT.COM> bryan@cbnewsd.ATT.COM (bryan.k.delaney) writes: >1.2M disks require a different write current >than the 360/720K disks so you should not use them at 360/720K >either. This raises yet another question: I have a 1.2M 5-1/4" drive in my AT clone. It is able to read/write low density 360K diskettes (using the 360K format) with no problems, and I swap 360K diskettes with my XT clone all the time with no problems. How does the 1.2M drive know to change its write current in order to successfully write a 360K floppy? Or, if it does not change its write current, the how do you explain the ability of thousands to read/write low density floppies in their high density drives? Curiouser and curiouser, Scott Coleman kubla@uiuc.edu
bill@bilver.UUCP (Bill Vermillion) (08/23/89)
In article <1836@garcon.cso.uiuc.edu> kubla@uiuc.edu (Kubla Khan) writes: >In article <1293@cbnewsd.ATT.COM> bryan@cbnewsd.ATT.COM (bryan.k.delaney) writes: >>1.2M disks require a different write current >>than the 360/720K disks so you should not use them at 360/720K >>either. > >This raises yet another question: I have a 1.2M 5-1/4" drive in my AT clone. >It is able to read/write low density 360K diskettes (using the 360K format) >with no problems, and I swap 360K diskettes with my XT clone all the time >with no problems. How does the 1.2M drive know to change its write current >in order to successfully write a 360K floppy? Or, if it does not change its >write current, the how do you explain the ability of thousands to read/write >low density floppies in their high density drives? That's simple. Part of the formatting routine. You format HD and it goes to the higher current. DD and it uses the lower. If the disks had been made different for hd/dd the problems might not exist. That is what TRIED to be done for the 3.5s. Put a hole in the disk to tell it HD, no hole it is DD. At one time, where there were almost no DS 5.25" drives some people used to cut another notch and another index hole. Then one drive mfr got wise and put in two sensor and two index leds and had a flipply drive. There is always someone wanting to get more out of a disk than it was designed for. If you want to do that, fine. But be sure you understand what you are doing and the consequences. Just because disks look alike doesn't mean they are. -- Bill Vermillion - UUCP: {uiucuxc,hoptoad,petsd}!peora!tarpit!bilver!bill : bill@bilver.UUCP Please use either of the above in replies. The Reply To: may be bogus!
pete@Octopus.COM (Pete Holzmann) (08/23/89)
In article <1836@garcon.cso.uiuc.edu> kubla@uiuc.edu (Kubla Khan) writes: >In article <1293@cbnewsd.ATT.COM> bryan@cbnewsd.ATT.COM (bryan.k.delaney) writes: >>1.2M disks require a different write current >>than the 360/720K disks so you should not use them at 360/720K >>either. > >This raises yet another question: I have a 1.2M 5-1/4" drive in my AT clone. >It is able to read/write low density 360K diskettes (using the 360K format) >with no problems, and I swap 360K diskettes with my XT clone all the time >with no problems. How does the 1.2M drive know to change its write current >in order to successfully write a 360K floppy? Or, if it does not change its >write current, the how do you explain the ability of thousands to read/write >low density floppies in their high density drives? You happen to be lucky. It will work for most of the people, most of the time. It will not work for everyone, all of the time. Failures seem to depend on particular diskette drive samples. In other words, your AT and XT happen to be a good match. But if I were you, I wouldn't try sending one of your 360K-written-on-1.2 diskettes in an expensive-important mailing to somebody across the country-- they might not be able to read it! If it is easy to re-do the process, then by all means, go ahead and write the 360K in the 1.2 drive. Perhaps the most important situation in which most of us need to be careful: If installing software that comes on 360K diskettes, into a 1.2 drive, I get VERY nervous if the diskettes are not write protected. I either write protect them first, or copy the originals and run the install from the backup (unless I am sure that the install process doesn't involve writing to the diskettes.) I've seen too many examples of original-floppies becoming unreadable after having been 'touched' by the install program. Pete -- Peter Holzmann, Octopus Enterprises |(if you're a techie Christian & are 19611 La Mar Ct., Cupertino, CA 95014 |interested in helping w/ the Great UUCP: {hpda,pyramid}!octopus!pete |Commission, email dsa-contact@octopus) DSA office ans mach=408/996-7746;Work (SLP) voice=408/985-7400,FAX=408/985-0859