Re: Extracting files off “unknown” 8 inch disks. Any thoughts…

Terry Stewart terry at
Thu May 4 18:39:36 CDT 2017

>And yet, if there were an RX02 somewhere on this VAX, I don't believe
you'd be able to read them at all... RX02 seeming more likely with a VAX.

Interestingly PUTR, does seem to accommodate this, and the kind of system I
have set up (i.e. 1.2 MB 5.25 inch in CMOS even though it's an 8 inch
drive).  From the readme file...

"SET x: type

        Sets the drive type for one of the four possible PC floppy
        drives A:-D: (note that actual PCs rarely have more than one or
        two floppy drives).  The type must be RX01, RX02, RX03, RX50,
        RX33, RX24, RX23, or RX26.  The default value for each drive is
        whatever was stored in CMOS memory by the ROM BIOS setup

        This command may be useful when the drive types stored in CMOS
        RAM are incorrect for some reason.  It's also helpful when an 8"
        drive, or a real DEC RX50 drive, has been attached to the PC
        using a D Bit "FDADAP" adapter, or something equivalent.  There
        is no standard for representing these drive types in CMOS RAM.
        Using real RX50 drives (or other 300 RPM quad-density drives
        such as the Tandon TM100-3 and TM100-4) is different from RX33s
        (which is what PUTR calls regular PC 1.2 MB drives) because the
        motor speed is slower, so the FDC chip must be programmed for a
        lower data rate to match."

 I didn't spend too much time on PUTR as it seemed to be more for the older
DEC OSs rather than Vax VMS.  VMS wasn't mentioned as an option in PUTR
which is why I spent more time experimenting with ODS2, which was VAX
specific. I said, PUTR tries to figure out what DEC OS (if any)
is on the disk and failed to find one.

Maybe I should play around with the switches in PUTR more before I give up


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