Optical Memory Card Device
hsmith at lasercard.com
Thu Apr 23 11:11:33 PDT 1998
* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* Hayden Smith <hsmith at lasercard.com>
At the next T10 meeting in May I will introduce a new SCSI device type,
the Optical Memory Card Reader/Writer. I would like to provide a brief
synopsis about the Optical Memory Card (OMC).
The OMC is a WORM media. It is physically identical in size to a
standard credit card with an embedded 35mm optical stripe.
The OMC is not new, it has been in existence for several years. The
physical characteristics, linear recording methods and logical data
structures have been fully defined in ISO documents 11693 and 11694.
The ISO document 11694 describes two physically different OMC's that use
two recording methods, pulse width modulation (PWM) and pulse position
OMC reader/writers have been available for approximately seven years.
There are two different types of reader/writers for encoding with the
PWM and PPM methods. The cards and reader/writers are not compatible
with each other.
The reader/writers are SCSI devices. To date each manufacturer has
implemented a set of custom SCSI commands for their device. These
command sets are incompatible, the methods with which they are designed
to use the media are also different.
Different parties within the industry have implemented a number of
device drivers and application development systems based on these
specific SCSI command sets and physical media properties. A number of
these systems are in wide spread use.
Some time ago the ISO working group for OMC's decided that a formal
interface specification was required for OMC devices. It was proposed
that the definition of the SCSI specification should be deferred to the
ISO SCSI standard group (SC25 WG4). A working group was formed by the
reader/writer manufactures in Japan. This working group will be
presenting a Committee Draft specification back to SC25. This will come
back, through our International Representative (Gene Milligan), to T10
for review. (I hope this paragraph is correct!)
It is my understanding that the Japanese working group is having
difficulty in forming a consensus on what the draft should contain. I
would like to help the T10 committee by providing information about
OMC's so that an effective review of the draft proposal from SC25 can be
made. I have various draft specifications from the members of the
Japanese working group that I can forward to any interested T10 members.
Please feel free to contact me directly.
It is my concern that the specification should be complete and provide
adequate information to allow a full understanding of both types of
media access methods.
I look forward to the OMC discussion at the SCSI Working Group Meeting
LaserCard Systems Corporation
2644 Bayshore Parkway
Email: hsmith at lasercard.com
Voice: 650 969 4428
Fax: 650 967 6524
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