derosa@cell.mot.COM (John DeRosa) (03/09/90)
I have found in my Macintosh travels that it is possible to format HD floppies as 400K or 800K in a DSDD drive (mac plus, se, II, etc). Why, you might ask?? Well I ran out of DSDD and really needed a 800K copy. BEWARE: If you now put this HD/800K hybrid floppy in a HD Drive (se-30, IIX, IIcx, etc), the floppy will be rejected with a "unrecognized disk, do you want to format?" dialog box. Upon review of the FDHD manual (a reference of last resort) it says just that. Apple (are you listening?) this is silly engineering in my book, not bad, just silly. =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= = John DeRosa, Motorola, Inc, Cellular Infrastructure Division = = e-mail: ...uunet!motcid!derosaj = = I do not hold by employer responsible for any information in this message = = nor am I responsible for anything my employer may do or say. = =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
jimvons@ashtate (Jim von Schmacht) (03/10/90)
In article <1567@diamond2.UUCP> derosa@cell.mot.COM (John DeRosa) writes: >Apple (are you listening?) this is silly engineering >in my book, not bad, just silly. The tracking on a formatted 1.44 is *Much* tighter than that used on the 800k, leaving some space between tracks when formatted as 800k in an older drive. When the HD floppies are tested, they are given a test format which is NOT completely overwritten by the old mechanisms. When a new drive which can read ALL the space available on the disk, it sees both good 800k and the garbage between tracks. In my book, one can't go back in time to tell the original SONY (note manufacturer/DESIGNER) team and tell them to use techniques which did not then exist. Bitch to SONY, as they are the ones who defined the standard, with Apples input being the ability to be variable as opposed to constant speed (the reason why PS/2's only get 720k while we get 800k, and the Amiga 880k) -- Jim von Schmacht Senior Member, Project Test Staff Ashton Tate Corporation Disclaimer: Standard Issue -------------------------------------------------------------------------------- "It isn't the years - it's the mileage" -Indiana Jones
ngg@bridge2.ESD.3Com.COM (Norman Goodger) (03/13/90)
In article <1567@diamond2.UUCP> derosa@cell.mot.COM (John DeRosa) writes: >I have found in my Macintosh travels that it >is possible to format HD floppies as 400K or 800K >in a DSDD drive (mac plus, se, II, etc). Why, you >might ask?? Well I ran out of DSDD and really >needed a 800K copy. >BEWARE: If you now put this HD/800K hybrid floppy >in a HD Drive (se-30, IIX, IIcx, etc), the floppy >will be rejected with a "unrecognized disk, do you >want to format?" dialog box. Upon review of >the FDHD manual (a reference of last resort) it >says just that. >Apple (are you listening?) this is silly engineering >in my book, not bad, just silly. You are assuming that this is the way that "Apple" engineered it, and that is not the case. You are dealing with two entirely different types of floppies from HD to 800K. HD diskettes are formulated to be more sensative to the lower voltages that the FDHD drives use in the HD mode. When you format and use an HD diskette as an 800 or 400K disk, the FDHD cannot effectively overwrite the stonger signals that the previous formatting created. I have not read of a way around this yet either. This is not something Apple cooked up to tick off FDHD users, its just the way that HD technology is and works. Perhaps you can blame Sony...its their drive If I remember correctly... ----- -- Norm Goodger SysOp - MacInfo BBS @415-795-8862 3Com Corp. Co-SysOp FreeSoft RT - GEnie. Enterprise Systems Division (I disclaim anything and everything) UUCP: {3comvax,auspex,sun}!bridge2!ngg Internet: ngg@bridge2.ESD.3Com.COM
aland@chaos.cs.brandeis.edu (Alan D Danziger) (03/13/90)
>In article <1567@diamond2.UUCP> derosa@cell.mot.COM (John DeRosa) writes: >>I have found in my Macintosh travels that it >>is possible to format HD floppies as 400K or 800K >>in a DSDD drive (mac plus, se, II, etc). >>BEWARE: If you now put this HD/800K hybrid floppy >>in a HD Drive (se-30, IIX, IIcx, etc), the floppy >>will be rejected with a "unrecognized disk, do you >>want to format?" dialog box. YOU CAN use the 1.4 meg, 800K formatted floppies in a FDHD drive... What you do is use a piece of (opaque) tape to cover the extra hole, and then put it in the drive! Then I would suggest copying and reformatting the disk properly... -- -=Alan=- aland@chaos.cs.brandeis.edu
derosa@cell.mot.COM (John DeRosa) (03/14/90)
ngg@bridge2.ESD.3Com.COM (Norman Goodger) writes: >In article <1567@diamond2.UUCP> derosa@cell.mot.COM (John DeRosa) writes: >>.......BEWARE: If you now put this HD/800K hybrid floppy >>in a HD Drive (se-30, IIX, IIcx, etc), the floppy >>will be rejected with a "unrecognized disk, do you >>want to format?" dialog box. Upon review o..... >.....When you >format and use an HD diskette as an 800 or 400K disk, the FDHD cannot >effectively overwrite the stonger signals that the previous formatting >created....... I did not know that the signals on a 800k and 400k disk are stronger than on a HD disk but this would make sense. The tracks must be closer together therefore the signal must be lower to not cause interference between adjacent tracks. This does not hold for the 800/400 difference as the only change was one sided vs. two sided. The problem with your argument is that I did not want to initialize the disk, just read it. The dialog I get tells me that the drive can not read the 800K "HD" disk while it can read a true 800K disk. This means that the drive recognises the disk by mechanical means, i.e. the notch extra "write protect" hole, instead of by sensing what is on the magnetic surface of the disk. The mechanical sensing must then change the bias of the head to read HD only and the "stronger signals" of the 800K confuses the reading of the data. I guess that it just comes down to a problem that is so obscure (who would ever waste an expensive HD disk as a DSDD?) that apple/sony took the easier approach. I'm an engineer, I can under stand the tradeoffs. =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= = John DeRosa, Motorola, Inc, Cellular Infrastructure Division = = e-mail: ...uunet!motcid!derosaj = = I do not hold by employer responsible for any information in this message = = nor am I responsible for anything my employer may do or say. = =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
sellers@ncrcae.Columbia.NCR.COM (Todd Sellers) (03/17/90)
[Discussion of using 800K formatted HD floppies in Apple's FDHD deleted] The problem with using an 800K formatted HD floppy in the FDHD is that they use two different recording technologies. The FDHD uses MFM (modified frequency modulation, I believe) for recording on HD floppies. It uses GCR (group coded recording) for writing on other floppies. I don't think there is any truth to the signals being stronger on one over the other. I can't believe that the erase head wouldn't be able to do its job. I do agree that it is annoying. +--------------------------------+--------------------------------------------+ | Todd Sellers | EMail to (sellers@ncrcae.Columbia.NCR.COM) | | NCR E&M Columbia | or (todd@pibtest.Columbia.NCR.COM) | | West Columbia, South Carolina | <THIS SPACE INTENTIONALLY LEFT BLANK> | | 29169 | <INSERT YOUR FAVORITE DISCLAIMER HERE> | +--------------------------------+--------------------------------------------+