davis@clocs.cs.unc.edu (Mark Davis) (12/02/89)
In article <52@qmsseq.imagen.com> pipkins@qmsseq.UUCP (Jeff Pipkins) writes: > ... > >The only thing on the con side is for existing users: it appears >that anytime you change ESDI controllers, you have to low-level >format again. No problem if the machine is new, and worth the >trouble if you're switching. > > ... Pardon my skeptism, but is this really true? In the case of ST 506/412 interface drives, the analog interface allows different type (read manufactures') controllers to be incompatible and require repeating the low level format. However, the ESDI interface is (1) all digital, and (2) relatively addressed. Since the ESDI controller cannot control either the level or the timing, I don't see how any controller would work with the drive, but still require the drive to be reformatted. Unfortunately, I have never tried to move disks between different brands of ESDI controllers, so I have no real world experience. Anyone have any examples? Perhaps some ESDI/Controller guru can comment. Thanks - Mark (davis@cs.unc.edu or uunet!mcnc!davis)
pipkins@qmsseq.imagen.com (Jeff Pipkins) (12/05/89)
My reply was from both ignorance and experience. Experience: I bought a Gateway 2000 with a 150 MB ESDI disk. They shipped it loaded with DOS and some programs, and of course, with an ESDI controller. I turned it off, took out their ESDI controller, plugged in the HardCache ESDI card from CompuAdd, turned it back on, and... No boot device, etc. I ran SETUP again (from ROM) and tried again. Same thing. Ignorance: I don't know why. The installation instructions for the HardCache tell you to do the low-level format after installing the board. Before I bought it, the salesman on the phone said that it would indeed work with the drive I had ordered, but that I *may* want to reformat it. He didn't say why. Could it be that before I didn't have 1:1 interleave? That would hardly explain the boot sector missing, though, would it?
keithe@tekgvs.LABS.TEK.COM (Keith Ericson) (12/06/89)
In article <10869@thorin.cs.unc.edu> davis@cs.unc.edu (Mark Davis) writes: <In article <52@qmsseq.imagen.com> pipkins@qmsseq.UUCP (Jeff Pipkins) writes: <>...anytime you change ESDI controllers, you have to low-level <>format again. <Pardon my skeptism, but is this really true? In playing with (switching between) the Adaptec 2322B and the WD 1007 ESDI controllers we've found that the drive must be reformatted (low level) to get it to talk to the new controller. kEITHe
jml@tw-rnd.SanDiego.NCR.COM (Michael Lodman) (12/07/89)
In article <10869@thorin.cs.unc.edu> davis@cs.unc.edu (Mark Davis) writes: >Since the ESDI controller cannot control >either the level or the timing, I don't see how any controller would work >with the drive, but still require the drive to be reformatted. It seemed to be true that a reformat was necessary when I switched from an Adaptec ESDI card to a Western Digital ESDI card. I really didn't take the time to find out why. -- +-----------------------------------------------------------+ | Michael Lodman Mike.Lodman@SanDiego.NCR.COM | | NCR Corporation - Distributed Systems Lab - San Diego | | 9900 Old Grove Rd. San Diego, CA. 92131 (619) 693-5353 | +-----------------------------------------------------------+
chasm@attctc.Dallas.TX.US (Charles Marslett) (12/07/89)
In article <6468@tekgvs.LABS.TEK.COM>, keithe@tekgvs.LABS.TEK.COM (Keith Ericson) writes: > In article <10869@thorin.cs.unc.edu> davis@cs.unc.edu (Mark Davis) writes: > <In article <52@qmsseq.imagen.com> pipkins@qmsseq.UUCP (Jeff Pipkins) writes: > <>...anytime you change ESDI controllers, you have to low-level > <>format again. > > <Pardon my skeptism, but is this really true? > > In playing with (switching between) the Adaptec 2322B and the WD 1007 ESDI > controllers we've found that the drive must be reformatted (low level) to get > it to talk to the new controller. The data format (byte stream or whatever) is usually (almost always?) portable between one controller and another, even if they use different controller chips -- that's because the definition of MFM and RLL define the bit stream on the media (the stuff going into the controller card), and the others define the interface equally well. All but SCSI drives pass a byte (or lower) level data stream to the controller card, however, and the header information, the CRC and the ECC information are not standardized. For example, one or another of the controller chip sets use 48, 56 or 64 bits of ECC data -- possibly compounded by the ECC algorithms being different for the same number of bits (here I'm really in over my head!). So portability between controllers is pretty much between two of the same model (or two WD/IBM compatible MFM controllers) or between two SCSI controllers. (And here, take compatibility with a small grain of salt. ;^) None of this may apply to the IPI standards (I don't know anything about them). > kEITHe Charles Marslett chasm@attctc.dallas.tx.us << corrections gratefully accepped, and perhaps ignored :)) >