media question (MO and tape)

From: Jerome H. Fine <>
Date: Thu Aug 7 14:24:01 2003

>Roger Merchberger wrote:

> >Rumor has it that may have mentioned these words:
> >My father was emptying his office and broght home a box full of back ups.
> >I have readers for most, except the following 2 :
> >Sony 5 1/4 Magneto Optical Disk EDM-1DA1s Rewritable
> >[snip]
> >I've googled around a bit and disovered very little about these medias
> >beyond the fact the MO disks can contain 600mb.
> There's two types of MO disks that are in the 600Mb range - 600Mb (300Mb
> per side, which IIRC are 512bytes/sector) and 650Mb (1024bytes/sector).
> AFAIK, these disks are not interchangeable. I have a MaxOptix Tahiti 1
> drive, which reads either the 600Mb disks, or Maxtor came out with their
> own 512byte/sector disks, that put more sectors on each track as there was
> room. I received 3 disks when I got it - one 1G platter (500Mb per side),
> and 2 600Mb platters, however, the 1G platter would *never* format
> correctly; methinks that the platter was just b0rked. It read/wrote the 2
> 600Mb platters just fine, tho...

Jerome Fine replies:

I have been using these magneto optical media for about 10 years,
on and off - mostly OFF since I first set up a system for a customer
in 1990. At that time, there were the newest system available and
had just managed to shift to RW media as opposed to WORM media
that I had used a few years before that.

The Sony EXTERNAL version is the Sony SMO S-501. Over the
years, larger and still larger drives and media have become available
with media that now holds about 5 GBytes.

I can't remember the media part numbers, but as Roger stated,
there are two types - 512 byte per sector media and 1024 byte
per sector media.

MOST of the time, I use ONLY the 512 byte per sector media
since I always have in mind that I want the media to be readable
on both my real DEC PDP-11 hardware (CQD 220/TM host
adapter) plus using a PC with Windows 98 SE and Ersatz-11
with BOTH systems running RT-11 (what else with an RT-11
addict use?).

BUT, while the software and firmware on the PDP-11 is unable
to read the 1024 byte per sector media, on the PC that was
not a problem the last time I tried it with Ersatz-11. But since
my experience is EXTREMELY limited with the 1024 byte
per sector media, I can't say for sure that it will always work.
The key seems to be that under Ersatz-11, I am able to use
the 1024 byte per sector media as if it is actually 512 bytes
per sector, but exactly how that is managed I have NO idea.

> I still have the drive; altho my main SCSI system is out-of-state right
> now; prolly until the beginning of next week.

I just did a few copies this week, so my Sony SMO S-501 seems
up and running.

> >Question : what drives would be able to read these media? Would they be
> >easily procurable for cheap?
> For stuff like this - Ebay would prolly be your best bet. Make sure, tho,
> that you get the right drive for the right MO disk you have; you can prolly
> get them pretty cheap nowadays tho.

On eBay, the Sony SMO S-501 drives seems to be available
only rarely. When they are available, the price is rarely over
$ US 10, so the shipping will cost you more.

The REO-650 uses a Sony C-501 controller and Sony D-501
drive, but the SCSI cable connection at the back does not daisy
chain correctly, so more than one drive is usually not possible.

The Sony D-501 drive by itself requires the Sony C-501
controller between the D-501 drive and the 50 pin connection
to the host adapter. In addition, the shipping charges also
include hidden handling charges.

Are these going to be the ONLY time you will be using
the magneto optical media? If so, buying a magneto optical
drive and getting it to work might be more difficult than
having someone recover the files for you. How many
of the magneto optical media do you have? Which
operating system was used to write the files?

Sincerely yours,

Jerome Fine
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Received on Thu Aug 07 2003 - 14:24:01 BST

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