NeXT MO disks

From: Jerome Fine <>
Date: Wed Feb 28 07:36:01 2001

>Jeff Hellige wrote:

> >Pinnacle called their drive the REO-650 and in a dual configuration it
> >was called an REO-1300. Since I also have an REO-650 and have
> >looked inside, I can verify that on the early models, this was the actual
> >hardware. Obviously, both the S501 and the REO-650 use the
> >identical media.
> I took a look at the Pinnacle drive today and it is a
> Pinnacle Micro Sierra Optical Hard Drive with a 1.3gig capacity on
> 5-1/4" removable media. Supposedly it is a double-sided cartridge
> capable of holding 650Mb per side. It appears to be a standard SCSI
> drive, but unfortunately I do not have any of the disks for it.

Jerome Fine replies:

As far as I know (or at least this is what I have always been told), the
MO drives which can use the larger capacity (NOT larger in physical
dimensions) media are also backward compatible with the lower
capacity media for both read and write at least downward one step.

There are now 5 GByte media and these drives can still read the
650 MByte original media for 5 1/4" drives, but are not able to
write to the original media.

So, it is almost a sure bet that your 1300 MByte drive can read and
write the 650 MByte media.

NOTE: The marketing hype produced by the drive manufactures
always stated (from what I can remember) that an MO drive had
a capacity equal the the capacity of the media rather than what the
drive could read on just one side of the media before it was flipped.

This would be like saying that the old 5 1/4" single-sided 180K floppy
drives were actually 360K if they could use a 5 1/4" flippy (a diskette
that had dual notches and index holes so that a single-sided drive
could read the other side of the floppy - I often used to do this with
an 8" floppy before I was told that turning the media in the other
direction inside the sleeve could dislodge sufficient dirt to make the
media inoperative - so I started to limit the practice to ONLY those
diskettes that I used for archive purposes).

Thus, a so-called 650 MByte MO drive like the Sony S501 or the
Pinnacle REO-650 can actually read/write ONLY 325 MBytes
per side (when 1024 byte per sector media are used - and only
295 MBytes per side when 512 bye per sector media are used),
although if the media is taken out and turned over and inserted
again, the other side of the media can also be used independently
to provide a total of 650 MBytes for the media, but still ONLY
325 MBytes maximum at a time for the actual MO drive.

In any case, if you have reached this far and want to attempt to
purchase the 590 MByte media, please reply ASAP. Anyone
else?? I suppose not since there have been NO other replies.

Sincerely yours,

Jerome Fine
Received on Wed Feb 28 2001 - 07:36:01 GMT

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