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The following is part 1 of a nice intro to CD technology written
by Andy Poggio in 1988. It appears here in its original form.
CD Summary Introduction
As requested by many people, I will post this CD Summary over the next
several days in five parts of which this is the first. I received
requests from rec.audio, comp.ivideodisc, and comp.graphics -- so I will
post it to all these groups. I'm not sure that it is appropriate for
comp.graphics but I DID receive multiple requests to post it there.
The summary is somewhat technical but more important it is factual: I
wrote it after reading the original CD standards documents available from
Sony or Philips to CD licensees. If you are interested in the standards
documents, you need to contact them directly -- sorry, I don't have a
specific contact or phone number.
I do work for Apple but this summary contains a minimum of Apple
references. I hope everyone agrees that the result is in keeping with net
policy on the matter.
--andy
CD Summary Part 1
CD-ROM Technical Summary
>From Plastic Pits to "Fantasia"
Andy Poggio
March, 1988
Abstract
This summary describes how information is encoded on Compact Disc (CD)
beginning with the physical pits and going up through higher levels of
data encoding to the structured multimedia information that is possible
with programs like HyperCard. This discussion is much broader than any
single standards document, e.g. the CD-Audio Red Book, while omitting much
of the detail needed only by drive manufacturers.
Salient Characteristics
1. High information density -- With the density achievable using optical
encoding, the CD can contain some 540 megabytes of data on a disc less
than five inches in diameter.
2. Low unit cost -- Because CDs are manufactured by a well-developed
process similar to that used to stamp out LP records, unit cost in large
quantities is less than two dollars.
3. Read only medium -- CD-ROM is read only; it cannot be written on or
erased. It is an electronic publishing, distribution, and access medium;
it cannot replace magnetic disks.
4. Modest random access performance -- Due to optical read head mass and
data encoding methods, random access ("seek time") performance of CD is
better than floppies but not as good as magnetic hard disks.
5. Robust, removable medium -- The CD itself is comprised mostly of, and
completely coated by, durable plastic. This fact and the data encoding
method allow the CD to be resistant to scratches and other handling
damage. Media lifetime is expected to be long, well beyond that of
magnetic media such as tape. In addition, the optical servo scanning
mechanism allows CDs to be removed from their drives.
6. Multimedia storage -- Because all CD data is stored digitally, it is
inherently multimedia in that it can store text, images, graphics, sound,
and any other information expressed in digital form. Its only limit in
this area is the rate at which data can be read from the disc, currently
about 150 KBytes/second. This is sufficient for all but uncompressed,
full motion color video.
CD Summary Part 2
CD Data Hierarchy
Storing data on a CD may be thought of as occurring through a data
encoding hierarchy with each level built upon the previous one. At the
lowest level, data is physically stored as pits on the disc. It is
actually encoded by several low-level mechanisms to provide high storage
density and reliable data recovery. At the next level, it organized into
tracks which may be digital audio or CD-ROM. The High Sierra
specification then defines a file system built on CD-ROM tracks. Finally,
applications like HyperCard specify a content format for files.
The Physical Medium
The Compact Disc itself is a thin plastic disk some 12 cm. in diameter.
Information is encoded in a plastic-encased spiral track contained on the
top of the disk. The spiral track is read optically by a noncontact head
which scans approximately radially as the disk spins just above it. The
spiral is scanned at a constant linear velocity thus assuring a constant
data rate. This requires the disc to rotate at a decreasing rate as the
spiral is scanned from its beginning near the center of the disc to its
end near the disc circumference.
The spiral track contains shallow depressions, called pits, in a
reflective layer. Binary information is encoded by the lengths of these
pits and the lengths of the areas between them, called land. During
reading, a low power laser beam from the optical head is focused on the
spiral layer and is reflected back into the head. Due to the optical
characteristics of the plastic disc and the wavelength of light used, the
quantity of reflected light varies depending on whether the beam is on
land or on a pit. The modulated, reflected light is converted to a radio
frequency, raw data signal by a photodetector in the optical head.
Low-level Data Encoding
To ensure accurate recovery, the disc data must be encoded to optimize the
analog-to-digital conversion process that the radio frequency signal must
undergo. Goals of the low level data encoding include:
1. High information density. This requires encoding that makes the best
possible use of the high, but limited, resolution of the laser beam and
read head optics.
2. Minimum intersymbol interference. This requires making the minimum
run length, i.e. the minimum number of consecutive zero bits or one bits,
as large as possible.
3. Self-clocking. To avoid a separate timing track, the data should be
encoded so as to allow the clock signal to be regenerated from the data
signal. This requires limiting the maximum run length of the data so that
data transitions will regenerate the clock.
4. Low digital sum value (the number of one bits minus the number of zero
bits). This minimizes the low frequency and DC content of the data signal
which permits optimal servo system operation.
A straightforward encoding would be to simply to encode zero bits as land
and one bits as pits. However, this does not meet goal (1) as well as the
encoding scheme actually used. The current CD scheme encodes one bits as
transitions from pit to land or land to pit and zero bits as constant pit
or constant land.
To meet goals (2) to (4), it is not possible to encode arbitrary binary
data. For example, the integer 0 expressed as thirty-two bits of zero
would have too long a run length to satisfy goal (3). To accommodate
these goals, each eight-bit byte of actual data is encoded as fourteen
bits of channel data. There are many more combinations of fourteen bits
(16,384) than there are of eight bits (256). To encode the eight-bit
combinations, 256 combinations of fourteen bits are chosen that meet the
goals. This encoding is referred to as Eight-to-Fourteen Modulation (EFM)
coding.
If fourteen channel bits were concatenated with another set of fourteen
channel bits, once again the above goals may not be met. To avoid this
possibility, three merging bits are included between each set of fourteen
channel bits. These merging bits carry no information but are chosen to
limit run length, keep data signal DC content low, etc. Thus, an eight
bit byte of actual data is encoded into a total of seventeen channel bits:
fourteen EFM bits and three merging bits.
To achieve a reliable self-clocking system, periodic synchronization is
necessary. Thus, data is broken up into individual frames each beginning
with a synchronization pattern. Each frame also contains twenty-four data
bytes, eight error correction bytes, a control and display byte (carrying
the subcoding channels), and merging bits separating them all. Each frame
is arranged as follows:
Sync Pattern24 + 3channel bits
Control and Display byte14 + 3
Data bytes12 * (14 + 3)
Error Correction bytes 4 * (14 + 3)
Data bytes12 * (14 + 3)
Error Correction bytes 4 * (14 + 3)
TOTAL588channel bits
Thus, 192 actual data bits (24 bytes) are encoded as 588 channel bits.
Editorial: A CD physically has a single spiral track about 3 miles long.
CDs spin at about 500 RPM when reading near the center down to about 250
RPM when reading near the circumference.
Disc with a 'c' or disk with a 'k'? A usage has emerged for these terms:
disk is used for eraseable disks (e.g. magnetic disks) while disc is used
for read-only (e.g. CD-ROM discs). One would presumably call a frisbee a
disc.
--andy
CD Summary Part 3
First Level Error Correction
Data errors can arise from production defects in the disk itself, defects
arising from subsequent damage to the disk, or jarring during reading. A
significant characteristic of these errors is that they often occur in
long bursts. This could be due, for example, to a relatively wide mark on
the disc that is opaque to the laser beam used to read the disc. A system
with two logical components called the Cross Interleave Reed-Solomon
Coding (CIRC) is employed for error correction. The cross interleave
component breaks up the long error bursts into many short errors; the
Reed-Solomon component provides the error correction.
As each frame is read from the disc, it is first decoded from fourteen
channel bits (the three merging bits are ignored) into eight-bit data
bytes. Then, the bytes from each frame (twenty-four data bytes and eight
error correction bytes) are passed to the first Reed-Solomon decoder which
uses four of the error correction bytes and is able to correct one byte in
error out of the 32. If there are no uncorrectable errors, the data is
simply passed along. If there are errors, the data is marked as being in
error at this stage of decoding.
The twenty-four data bytes and four remaining error correction bytes are
then passed through unequal delays before going through another
Reed-Solomon decoder. These unequal delays result in an interleaving of
the data that spreads long error bursts among many different passes
through the second decoder. The delays are such that error bursts up to
450 bytes long can be completely corrected. The second Reed-Solomon
decoder uses the last four error correction bytes to correct any remaining
errors in the twenty-four data bytes. At this point, the data goes
through a de-interleaving process to restore the correct byte order.
Subcoding Channels and Blocks
The eight-bit control and display byte in each frame carries the subcoding
channels. A subcoding block consists of 98 subcoding bytes, and thus 98
of the 588-bit frames. A block then can contain 2352 bytes of data.
Seventy-five blocks are read each second. With this information, it is
now straightforward to calculate that the CD data rate is in fact correct
for CD digital audio (CD-DA):
Required CD digital audio data rate: 44.1 K samples per second * 16 bits
per sample * 2 channels = 1,411,200 bits/sec.
CD data rate: 8 bits per byte * 24 bytes per frame * 98 frames per
subcoding block * 75 subcoding blocks per second = 1,411,200 bits/sec.
The eight subcoding channels are labeled P through W and are encoded one
bit for each channel in a control and display byte. Channel P is used as
a simple music track separator. Channel Q is used for control purposes
and encodes information like track number, track type, and location
(minute, second, and frame number). During the lead-in track of the disc,
channel Q encodes a table of contents for the disk giving track number and
starting location. Standards have been proposed that would use the
remaining channels for line graphics and ASCII character strings, but
these are seldom used.
Track Types
Tracks can have two types as specified in the control bit field of
subchannel Q. The first type is CD digital audio (CD-DA) tracks. The
two-channel audio is sampled at 44.1 Khz with sixteen bit linear sampling
encoded as twos complement numbers. The sixteen bit samples are separated
into two eight-bit bytes; the bytes from each channel alternate on the
disc. Variations for audio tracks include pre-emphasis and four track
recording.
The other type of track specified by the subchannel Q control bit field is
the data track. These must conform to the CD-ROM standard described
below. In general, a disc can have a mix of CD digital audio tracks and a
CD-ROM track, but the CD-ROM track must come first.
Editorial: This first level error correction (the only type used for CD
Audio data) is extremely powerful. The CD specification allows for discs
to have up to 220 raw errors per second. Every one of these errors is
(almost always) perfectly corrected by the CIRC scheme for a net error
rate of zero. For example, our tests using Apple's CD-ROM drive (which
also plays audio) show that raw error rates are around 50-100 per second
these days. Of course, these are perfectly corrected, meaning that the
original data is perfectly recovered. We have tested flawed discs with
raw rates up to 300 per second. Net errors on all of these discs? Zero!
I would expect a typical audio CD player to perform similarly. Thus I
expect this raw error rate to have no audible consequences.
So why did I say "almost always" corrected above? Because a sufficiently
bad flaw may produce uncorrectable errors. These very unusual errors are
"concealed" by the player rather than corrected. Note that this
concealment is likely to be less noticeable than even a single scratch on
an LP. Such a flaw might be a really opaque finger smudge; CDs do merit
careful handling. On the two (and only two) occasions I have found these,
I simply sprayed on a little Windex glass cleaner and wiped it off using
radial strokes. This restored the CDs to zero net errors.
One can argue about the quality of the process of conversion of analog
music to and from digital representation, but in the digital domain CDs
are really very, very good.
CD Summary Part 4
CD-ROM Data Tracks
Each CD-ROM data track is divided into individually addressable blocks of
2352 data bytes, i.e. one subcoding block or 98 frames. A header in each
block contains the block address and the mode of the block. The block
address is identical to the encoding of minute, second, and frame number
in subcode channel Q. The modes defined in the CD-ROM specification are:
Mode 0 -- all data bytes are zero.
Mode 1 -- (CD-ROM Data):
Sync Field - 12 bytes
Header Field - 4
User Data Field - 2048
Error Detection Code - 4
Reserved - 8
Error Correction - 276
Mode 2 -- (CD Audio or Other Data):
Sync Field - 12 bytes
Header Field - 4
User Data Field - 2048
Auxiliary Data Field - 288
Thus, mode 1 defines separately addressable, physical 2K byte data blocks
making CD-ROM look at this level very similar to other digital mass
storage devices.
Second Level Error Correction
An uncorrected error in audio data typically results in a brief, often
inaudible click during listening at worst. An uncorrected error in other
kinds of data, for example program code, may render a CD unusable. For
this reason, CD-ROM defines a second level of error detection and error
correction (EDC/ECC) for mode 1 data. The information for the EDC/ECC
occupies most of the auxiliary data field.
The error detection code is a cyclic redundancy check (CRC) on the sync,
header, and user data. It occupies the first four bytes of the auxiliary
data field and provides a very high probability that uncorrected errors
will be detected. The error correction code is essentially the same as
the first level error correction in that interleaving and Reed-Solomon
coding are used. It occupies the final 276 bytes of the auxiliary data
field.
Editorial: This extra level of error correction for CD-ROM blocks is one
of the many reasons that CD-ROM drives are much more expensive than
consumer audio players. To perform this error correction quickly requires
substantial extra computing power (sometimes a dedicated microprocessor)
in the drive.
This is also one reason that consumer players like the Magnavoxes which
claim to be CD-ROM compatible (with their digital output jack on the back)
are useless for that purpose. They have no way of dealing with the CD-ROM
error correction. They also have no way for a computer to tell them where
to seek.
Another reason that CD-ROM drives are more expensive is that they are
built to be a computer peripheral rather than a consumer device, i.e. like
a combination race car/truck rather than a family sedan. One story,
probably apocryphal but not far from the truth, has it that a major
Japanese manufacturer tested some consumer audio players to simulate
computer use: they made them seek (move the optical head) from the inside
of the CD to the outside and back again. These are called maximum seeks.
The story says they managed to do this for about 24 hours before they
broke down. A CD-ROM drive needs to be several orders of magnitude more
robust. Fast and strong don't come cheap.
CD Summary Part 5
The High Sierra File System Standard
Built on top of the addressable 2K blocks that the CD-ROM specification
defines, the next higher level of data encoding is a file system that
permits logical organization of the data on the CD. This can be a native
file system like the Macintosh Hierarchical File System (HFS). Another
alternative is the High Sierra (also known as the ISO 9660) file standard,
recently approved by the National Information Standards Organization
(NISO) and the International Standards Organization (ISO), which defines a
file system carefully tuned to CD characteristics. In particular:
1. CDs have modest seek time and high capacity. As a result, the High
Sierra standard makes tradeoffs that reduce the number of seeks needed to
read a file at the expense of space efficiency.
2. CDs are read-only. Thus, concerns like space allocation, file
deletion, and the like are not addressed in the specification.
For High Sierra file systems, each individual CD is a volume. Several CDs
may be grouped together in a volume set and there is a mechanism for
subsequent volumes in a set to update preceding ones. Volumes can contain
standard file structures, coded character set file structures for
character encoding other than ASCII, or boot records. Boot records can
contain either data or program code that may be needed by systems or
applications.
High Sierra Directories and Files
The file system is a hierarchical one in which directories may contain
files or other directories. Each volume has a root directory which serves
as an ancestor to all other directories or files in the volume. This
dictates an overall tree structure for the volume.
A typical disadvantage in hierarchical systems is that to read a file
(which must be a leaf of the hierarchy tree) given its full path name, it
is necessary to begin at the root directory and search through each of its
ancestral directories until the entry for the file is found. For example,
given the path name "Wine Regions:America:California:Mendocino", three
directories (the first three components of the path name) would need to be
searched. Typically, a separate seek would be required for each
directory. This would result in relatively poor performance.
To avoid this, High Sierra specifies that each volume contain a path table
in addition to its directories and files. The path table describes the
directory hierarchy in a compact form that may be cached in computer
memory for optimum performance. The path table contains entries for the
volume's directories in a breadth-first order; directories with a common
parent are listed in lexicographic order. Each entry contains only the
location of the directory it describes, its name, and the location in the
path table of its parent. This mechanism allows any directory to be
accessed with only a single CD seek.
Directories contain more detailed information than the path table. Each
directory entry contains:
Directory or file location.
File length.
Date and time of creation.
Name of the file.
Flags:
Whether the entry is for a file or a directory.
Whether or not it is an associated file.
Whether or not it has records.
Whether or not it has read protection.
Whether or not it has subsequent extents.
Interleave structure of the file.
Interleaving may be used, for example, to meet realtime requirements for
multiple files whose contents must be presented simultaneously. This
would happen if a file containing graphic images were interleaved with a
file containing compressed sound that describes the images.
Files themselves are recorded in contiguous (or interleaved) blocks on the
disc. The read-only nature of CD permits this contiguous recording in a
straightforward manner. A file may also be recorded in a series of
noncontiguous extents with a directory entry for each extent.
The specification does not favor any particular computer architecture. In
particular all significant, multibyte numbers are recorded twice, once
with the most significant byte first and once with the least significant
byte first.
Multimedia Information
Using the file system are applications that create and portray multimedia
information. While it is true that a CD can store anything that a
magnetic disk can store (and usually much more of it), CDs will be used
more for storing information than for storing programs. It is the very
large storage capacity of CDs coupled with their low cost that opens up
the possibilities for interactive, multimedia information to be used in a
multitude of ways.
Programs like HyperCard, with it's ease of authoring and broad
extensibility, are very useful for this purpose. Hypercard stacks, with
related information such as color images and sound, can be easily and
inexpensively stored on CDs despite their possibly very large size.
Editorial: The High Sierra file system gets its name from the location of
the first meeting on it: the High Sierra Hotel at Lake Tahoe. It is much
more commonly referred to as ISO 9660, though the two specifications are
slightly different.
It has gotten very easy and inexpensive to make a CD-ROM disc (or audio
CD). For example, you can now take a Macintosh hard disk and send it with
$1500 to one of several CD pressers. They will send you back your hard
disk and 100 CDs with exactly the same content as what's on your disk.
This is the easy way to make CDs with capacity up to the size of your hard
disk (Apple's go up to 160 megabytes). True, this is not a full CD but
CDs don't need to be full. If you have just 10 megabytes and need 100
copies, CDs may be the best way to go.
If you are buying a CD-ROM drive, there are several factors you might
consider in making your choice. Two factors NOT to consider are capacity
and data rate. The capacity of all CD-ROM drives is determined solely by
the CD they are reading. Though you will see a range of numbers in
manufacturers' specs (e.g. 540, 550, 600, and 650 Mbytes), any drive can
read any disc and so they are all fundamentally the same. All CD-ROM
drives read data at a net 150 Kbytes/sec for CD-ROM data. Other data
rates you may see may include error correction data (not included in the
net rate) or may be a mode 2 data rate (faster than mode 1). All drives
will be the same in all of these specs.
[ Editorial: The last paragraph is wrong on both points. This may have
been true in 1988, when this article was written, but is no longer true
today (in 1992). A few drives cannot read CDROMs with more than about
620 megabytes on them. There is a huge variation in speed. Today only
the slowest drives read at 150 kb/sec. Most read at least 300 and at
least one (the Pioneer DRM-600X) reads at 600 kb/sec. ]
===============================================================================
- *** Reprinted from Atari Explorer Online Volume 2, Issue 1, Januari 1993. ****
||| The ALBERT File: CD-ROM & Photo CD ...... Coming to an Atari near you
||| By: Albert Dayes
/ | \ CompuServe: 70007,3615 GEnie: AEO.1
---------------------------------------------------------------------
/***********************************************************************
Title: CD.DOC
Created: December 10, 1992
Last Modified: December 31, 1992
Purpose: A Guide to Optical Storage with a special focus on
CD-ROM and Kodak's Photo CD on the Atari platform.
Author: Albert Dayes
Legal Notes: Copyright 1992 Albert Dayes, All Rights Reserved
Some portions Copyright 1992 Rich Bowers, used by
permission.
Version: 1.0
- **********************************************************************/
CD-ROM on the Atari Platform NOW!
Atari owners have been waiting with baited breath for CD-ROM to arrive
on the Atari platform. Actually the CD-ROM portion has been around for
quite a while but now you can add Photo CD to the long list of tools
available on the Atari ST, TT030, and Falcon030.
This is a guide to CD-ROM in general and what it all means to the user.
Its purpose is to go beyond the endless lists of terms on optical media
and CD-ROM and explain how it can work for you. Included is a glossary
of terms so one can have something to refer to when an unknown term
appears.
Thanks are in order to several people but one in particular is Rich
Bowers (CO-SYSOP on CD-ROM forum on COMPUSERVE) who provided answers to
quite a few questions in this document. He does an outstanding job as you
will notice when you start reading it.
/***********************************************************************/
Special Thanks to:
Steve Luper = Sysop of the CD-ROM forum on COMPUSERVE (GO CD-ROM)
Rich Bowers = Co-Sysop of the CD-ROM forum on COMPUSERVE and Executive
Director of Optical Publishing Association (OPA). Rich
willingly provided answers to some of the questions in
this document; specifically questions: A, B, C, D, E,
which are Copyright 1992 Rich Bowers.
Paul McAfee = of Kodak (Press Relations Manager for Photo CD) - for
all his help with my Photo CD questions. Also for all
of Kodak's Press Releases dealing with Photo CD.
Scott Brownstein = Manager of Advanced Projects at Kodak - for answering
questions on technical details on CD technology and
Photo CD.
Additional Thanks:
Ron Luks = Chief Sysop of the Atari forums on COMPUSERVE (GO ATARI)
Paul Wisotzke = of Kodak Information Center (KIC)
Joel White = of Kodak Information Center (KIC)
/********************************************************************/
TABLE OF CONTENTS
A) What is CD-ROM?
B) What is the difference between "disc" and "disk"?
C) How standardized is CD-ROM?
D) What is SCSI and why is it important to CD-ROM?
E) How is CD-ROM related to laserdisc (videodisc)?
F) What are the CD-ROM standards?
G) What benefit is CD-ROM to me?
H) How much does it cost to make my own CD-ROM disc?
I) What is Kodak's Photo CD?
J) What is multi-session and why is it important to Photo CD?
K) Summary of an interview Scott Brownstein - manager of Advanced Projects
at Kodak.
L) Which is the best CD-ROM drive to buy for use on the Atari?
CONTACTS for ATARI Related CD-ROM and/or PHOTO CD products.
ISO-9660 filesystem made EASY
MULTI-SESSION made EASY
Making My OWN CD-ROM made EASY
An Atari Dream CD-ROM
GLOSSARY OF TERMS
CD-ROM DRIVE MANUFACTURERS
SOURCES OF INFORMATION ON OPTICAL MEDIA and SPECIFICATIONS
/*********************************************************************/
--==-- A) What is CD-ROM?
Physically, CD-ROM is the same compact disc that has become the standard
for the delivery of music. It is a plastic disc, 4-3/4" (12cm) in
diameter, on which data is recorded digitally. There is also a 3-1/2"
(8cm) form factor, equivalent to the mini-disc music product (although
this size is currently used only in Sony's Data DiscMan portable reader).
Because compact disc is a digital medium, it is a natural for delivery of
information of a variety of types - text, photos, audio,
computer-generated graphics, video and software - to a computer host.
CD-ROM has many unique features that suit it to information delivery. It
has a capacity of approximately 650 million characters (about 200 million
characters for the mini-disc). This capacity is analogous to any number of
measures. It is equivalent to over 1500 high-density floppies (1.44
megabyte disk size), or over 200,000 pages of printed text. By using a
lower sampling frequency for recording audio, it can hold many hours of
sound. It can hold upwards of 10,000 high quality photographs. By using
compression and decompression techniques (in partnership with the host
computer), these numbers can be greatly increased.
It is a very durable delivery medium. It is not indestructible, but it is
not subject to magnetic fields as hard disks are, and it can be mailed
with minimal protection. The disc itself weighs only an ounce or two, and
thus is highly portable. Technical standards enable a CD-ROM to be
"portable," in a computer sense, across many types of systems.
Because compact discs are mastered and inexpensively replicated in
quantity, CD-ROM is an ideal medium for "publishing" many copies of large
volumes of information. Because the discs are digital and have a high
capacity, they are amenable to entirely new categories of products - such
as multimedia - which have not been "published" in the past, because there
was no practical means to do so.
Thus there are large databases that have formerly been accessible only
online being published, in whole or in part, on CD-ROM. We see multimedia
presentations, which formerly were only accessible from large magnetic
discs, being packaged and distributed like other publications. CD-ROM has
inspired new methods for the delivery of existing materials, it has
inspired the creation of radically new materials, and it has inspired a
complete re-thinking of traditional publishing and distribution processes.
For this reason, we see CD-ROM as the catalyst and the means for a
"revolution" in publishing.
Compact disc was created and defined in a series of proprietary standards
by a joint effort of Sony and Philips. Compact disc-audio was introduced
as a commercial product in 1982. The first CD-ROM applications were
introduced for sale in late 1985. CD-I was announced in 1986, the first
commercial products were sold in the fall of 1991. CDTV was first sold in
the spring of 1991. The MPC specification was introduced in 1991, and the
first MPC-compliant upgrade kits and titles were launched in late 1991. Of
course, there are new CD-ROM based devices coming from Sony (via the
handheld Data Discman and the so-called Bookman), Tandy (VIS) and
cartridge-based game systems producers like Sega, NEC and Nintendo.
CD-ROM differs from CD-audio in that certain data are added to meet the
needs of computer operating systems, and to assure that the data you
receive are the same as the data originally recorded. To meet the needs of
a computer's operating system, a header is required that describes the
nature and location of the data on the disc. This is called a
volume-table-of contents, or VTOC in computer-ese. The integrity of the
data is assured through the use of multiple layers of error-correction
codes, which further distinguish CD-ROM from CD-audio. The structure and
use of these components are mandated by standards such as the Yellow Book
(which defines the recording of data for computer use, extending the
CD-audio standard described in the Red Book), and ISO 9660, an
international standard that defines the VTOC.
Within these constraints, there are many ways to deliver information for
specific platforms and applications. These differing methods have lead to
the proliferation of "CD-ROM formats" - such as CD-ROM-XA, CD-I and so
forth. These are described in detail below. However, all formats conform
first to the CD-audio standard, second to the CD-ROM standard, and third
to the extended specifications required for each format. In short, CD-I is
a format of CD-ROM, CDTV is a format of CD-ROM, etc.
CD-ROM requires a computer to read, interpret and display data, and to
deal with the interactive nature of CD-ROM access and use. The initial
products were exclusively computer host-based: the drive is attached as a
peripheral to a personal computer. In recent years, a new category of
products has emerged: the so-called "information appliances," such as
CD-I, VIS, Data Discman, etc. These products also use computers, but the
computer-ness is embedded in the use of the product. The technical aspects
of many of these products are described below.
--==-- B) What is the difference between "disc" and "disk"?
The convention is that "disc" refers to optical media, while "disk" refers
to magnetic media. The distinction is important, because the different
spellings signify very different products. Most trade media seem to be
oblivious to the distinction.
By the way, the absolutely correct way of referring to CDROM is "CD-ROM."
This author and others often remove the hyphen because a) it does not
change the meaning and b) it is easier to type. CD-ROM should not be
shortened to "CDR" because CD-R refers to compact disc-recordable
systems, or CD-Write Once.
--==-- C) How standardized is CD-ROM?
CD-ROM is one of the most thoroughly standardized computer sub-systems in
the history of the business. The medium is standard, and the drives that
read the medium are defined by standards. The format of the header which
enables cross-platform access to data - ISO 9660 - is standardized.
Not all is perfect, however. CD-ROM developers must do business in the
real world comprised of a variety of computer platforms, operating
systems, and other factors. So the information content on a CD-ROM remains
- to some extent - dependent on the system which will access and use the
data.
--==-- D) What is SCSI, and why is it important to CD-ROM?
The Small Computer System Interface (SCSI - generally pronounced
"scuzzee"), is a standard which permits the connection of up to 7
different devices to the host computer. Each device still requires its own
driver software.
The use of SCSI requires an interface board inserted in an expansion slot
of a PC. Macintosh and UNIX systems are natively SCSI-based. One advantage
of SCSI is that expansion slots are conserved - instead of a proprietary
interface board required for each device, several can share the same
interface. Devices such as scanners, printers, hard drives, CD-R drives
like Philips CDD-521, MO drives, WORM drives, and some network cards
(usually ethernet), can use SCSI in addition to CD-ROM drives.
Virtually all CD-ROM drive manufacturers have one or more models that are
SCSI compatible. In most cases, the consumer has a choice of acquiring the
interface board from the CD-ROM drive vendor, or using a board from a
third party. At the risk of offending some vendors by exclusion, note that
interfaces from Adaptec, UltraStor and Future Domain receive many comments
on the CD-ROM Forum.
A new variation on SCSI has emerged. The original standard, now called
SCSI-1, has been enhanced with a new specification called SCSI-2. SCSI-2
has standardized audio commands for CD-ROM drives. So using a SCSI-2
"play" command will work on all SCSI-2 CD-ROM drives, eliminating the need
for unique audio device drivers for each CD-ROM drive. SCSI-2 is
backwardly compatible with SCSI-1, so a SCSI-1 device will work with a
SCSI-2 interface board.
In addition, SCSI-2 will offer faster transfer speed for devices that can
support it, and the capability to transfer 16- and 32-bit paths in
addition to the normal 8-bits. Standard SCSI connectors have 50 pins, a
new wide SCSI has a 68-pin connector. SCSI-2 has not been formally
approved yet, although some vendors are offering products with these
features.
(My thanks to Albert Dayes for providing the majority of this data.)
NOTE: The Atari TT is SCSI based and the Atari Falcon030 is SCSI-2
based, and with Atari and third party host adapters like ICD one
can have SCSI-1 or SCSI-2 adapters available for use on the Atari
ST series of computers.
--==-- E) How is CD-ROM related to laserdisc (videodisc)?
In the mid-1970's a number of companies introduced a 12" disc product
which could deliver movies and other graphical/video content superior to
that of videotape formats. What we know now as the laserdisc, or
videodisc, has been up, and it has been down, in terms of market
acceptance. It has been of consistent interest for training and
educational purposes, because it provided an "interactive" capability for
the use of video material that tape does not provide. Recently, videodisc
has seen a resurgence in the consumer marketplace.
Laserdisc is an analog format: the data are recorded on the disc just as
in any other analog medium like video or audio tape. CD-ROM is a digital
format. Laserdisc gives a superior quality video picture and high quality
sound. Laserdisc is not a good medium for delivery of text, software or
manipulatable data elements. Digital video technology is still being
perfected, but no one would claim that CD-ROM can deliver as a good a tv
picture as laserdisc.
The advantage CD-ROM brings to the table is the ability to mix and match a
wide variety of data elements through retrieval or authoring software. If
the sole requirement of the consumer is high-quality video, then laserdisc
is the right product to buy. If, however, the requirement is for random
access to large volumes of mixed-format data, a high degree of
interactivity, or converging published data with other computer
applications, then CD-ROM is the right product. It is this flexibility
(albeit with limitations in the video arena) that has captured the
attention of many new publishers.
--==-- F) What are the CD-ROM standards?
The standards have two levels, the physical and logical level. The
physical defines how the actual disc is made (size, material, etc). The
logical defines how a device driver or operating system will view the data
that is placed on the disc.
There is a broad standard that gives the physical characteristics of the
disc and this is called the "Yellow Book." The "Yellow Book" defines all
the physical requirements for any CD-ROM disc. The "Yellow Book" has
everything basically that the "Red Book" has and more. Audio CDs are
defined by the "Red Book," and the "Yellow Book" allows for CD-ROM to have
either data or audio tracks or a hybrid that allows for both types of
tracks on a CD-ROM. This hybrid is usually referred to as mixed mode.
The logical format one can also think of as the filesystem of the CD-ROM.
In the 1986 the High Sierra format was made and when the ISO
(International Standards Organization) modified it became the ISO-9660
standard. This ISO-9660 standard is very important since it allows for any
type of system to be able to read it. Platform independence was one of the
very important features of the ISO-9660 standard. One does notice that it
has a strong MS-DOS influence in its overall design and in some of the
limits.
It is important to note that logical format can be any filesystem and does
not necessarily mean ISO-9660. For example some discs are in Apple
Macintosh HFS (Hierarchical File System) rather than ISO-9660.
CD-ROM/XA allows everything listed above and it added a compressed audio
capability. Also, the layouts of the tracks on the physical disc have been
modified to allow for more specific track information. CD-I and Photo CD
are built on top of this enhancement to CD-ROM. The audio is ADPCM and it
is interleaved with data. This allows for nicely synchronized audio
without taking away CPU time. It is not used very much currently but this
may change in the future.
Rich Bowers, Executive Director of the OPA sums it up nicely.
Its primary purpose was to interleave audio with other data, in effect
to synchronize audio with a visual presentation. Think in terms of
making the sound come out in synch with the lips moving.
When you consider it, there are basically two kinds of data: those
which are time-sequence dependent and those which are not. A database
retrieval or the presentation of a single graphic is independent of
other data from a time perspective. Audio is absolutely tied to a
time-sequence. Video data is also dependent on time-sequencing,
although we have some freedom in representing motion because the
psychological phenomenon that lets us fill in the blanks in our minds,
in essence to see things that aren't there. Audio is less flexible
that way.
XA is a physical means of storing data that depends on the
time-sequencing of related data. A new standard called HyTime (about
which I hope to have a file uploaded soon) is a production technique
for dealing with time-sequenced data, based on the SGML mark-up
strategy.
Rock Ridge extensions to the ISO-9660 standard allow all the features of
the UNIX filesystem to be used. These extra information is stored the
System Use fields defined in the ISO-9660 standard. The information that
is stored there for UNIX/POSIX include uid, gid, permissions, file mode
bits, file types, setuid, setgid, sticky bit, file links, device nodes,
symbolic links, POSIX filenames, reconstruction of deep directories and
time stamps.
--==-- G) What benefit is CD-ROM to me?
The benefits can be quite numerous once you start listing all of them.
First we can discuss some of the possible uses for CD-ROMs.
Desk Top Publishing = Large amount of clip art, fonts and images can be
& Graphic Designers found for relatively low cost from many vendors.
Kodak Photo CD's can have a great impact in this
area as well.
Musicians & = CD-ROM discs can hold a huge amount of different
Audio Engineers samples and sound effects covering a large range
of topics at a very reasonable cost. Generic
sequences for MIDI will also be available in the
future.
Writers = Reference materials including dictionaries,
quotations and complete works by a large variety
of authors on one disc.
Programmers = Walnut Creek has 600 megabytes of source code for
under $40. Being able to store all that source
code in a concise place is a major benefit of
CD-ROM. One can get C source code which includes
a part of BSD UNIX (including the networking code),
X-Windows (X11R5), and entire GNU source code for
under $50. The entire library of the C USERS
JOURNAL plus all of the program source code
listings in the magazine (since 1987) for $50.
Marketing Managers = Census data can be purchased on CD-ROM in a raw
ascii data format and can be loaded into a database
or spreadsheet for endless "what if" type of
manipulation. Also there are many CD-ROMs that
target specific geographical regions that can be
very useful for niche markets.
Space Exploration = One can purchase CD-ROMs from the different space
missions for under $10 each from the NASA Space
Science Data Center.
Geology and = The US Geological survey has quite a few CD-ROMs
Mapping consisting of the entire USA or specific geographical
regions for quite a low cost. One interested in
graphics could generate some nice 3D graphic models.
Games = Games are coming to CD-ROM slowly but surely.
Health Providers = Important Medical Journals, and medical research
papers are available now on CD-ROM.
Lawyers = There are a few CD-ROMs of all the laws for specific
states and even compilations from West Publishing,
one of the largest law publishers which also includes
an on-line service for lawyers.
Optical Publishing = Custom designed CD-ROMs that contain complete
specifications and documents is a very strong
growing area of the CD-ROM market. This also
includes multi-media titles as well and much
more.
Education = Interactive learning using multi-media on CD-ROMs.
Research papers and much more are available in this
exploding market.
Religion = The Bible (in many versions), Koran and many other
works from different religions all on one disc.
Family Album = Store all the family pictures on a single disc using
Photo CD.
Anyone = Archiving important data for later retrieval. This
data can be anything: financial, marketing, C source
code, software, games, papers, audio, etc.
General = There is a tremendous amount of information on
CD-ROM discs in just plain ASCII format that anyone
can use with their computer. Just import it into
a word processor, spreadsheet or database and
there are endless possibilities.
One could go on and on about the possibilities.
What types are available for the Atari currently?
All discs that are ISO-9660 compliant and contain raw data, sound, clip
art, images, etc, can be used on the Atari immediately. Currently there
are not any CD-ROMs specifically designed for the Atari ST except for a
couple that include many different shareware programs. You can not run
programs on CD-ROMs designed for other platforms like the IBM PC or the
MAC; it just like attempting to run a PC program from your Atari... it
won't work.
This will change once more people get CD-ROM drives on the Atari and start
asking for titles. The Atari Falcon030 and the TT030 have both been to
shown to work with Kodak's Photo CD at the recent Fall 1992 Comdex show.
It was working directly with an application (a DeskTop Publishing program)
called Calamus SL.
The key here is the hardware and software is available to use CD-ROMs on
the Atari is available NOW! Both Atari and ICD have drivers available that
work with SCSI CD-ROM drives.
--==-- H) How much does it cost to produce my own CD-ROM disc?
One can take 600 megabytes of a hard disk and save it to tape, then send
to some specific publishers and they will convert it to a single CD-ROM
for $200. One could probably use Beckemeyer's SCSI TAPE KIT or Oregon
Research Associates Diamond Back III to perform that operation.
One should check to be sure that the publisher can handle the current tape
format. The format usually used is TAR. TAR allows for files to be backed
up and restored on many different platforms. In addition, it can split
large files and each tape is independent of the other tapes when it comes
to restoration.
If one wants to be able to create One-Offs or CD-WO discs one needs to
spend around $12,000 for everything one would need. Then you can create
your own discs at your convenience and then send it off to the duplicator
for more copies when you need to. The CD-WO media is under $50 so it isn't
too expensive from a media point of view.
The most expensive part of the creating One-Offs is CD-Writer itself which
ranges from around $7000 and up depending on the features available.
These devices are usually SCSI devices and create a CD disc (audio or
data) in about 30 to 70 minutes on average. The software to create a disc
image (usually called the pre-mastering phase) is around $2500 and up.
Plus a computer to handle all of that can be $3000 and up. Prices are
dropping all the time so it might now be too long before many people have
personal CD-Writers.
--==-- I) What is Kodak's Photo CD?
Is a new standard based upon an extension CD-ROM/XA specification since
it adds additional information at the track level. This new format is
called the CD-Bridge format and it is what Kodak's Photo CD is based on.
The Photo CD system, jointly developed by Eastman Kodak Company
and Philips stores 35-mm photographs as well as text, graphics
and sound on compact discs. It offers several benefits to
consumers and professionals:
* rapid retrieval and display of images
* consistent and optimum image quality
* access to powerful image manipulation
* access to high-quality, continuous tone printing
* support for a wide range of colors;
* image duplication without degradation
* support for current and future television formats
How much does it cost to get my film on a Photo CD?
The average cost is around $24 for an average roll of film. One gets the
negatives, prints and a Photo CD. One should contact their local
photofinisher or Kodak for the location of the one in your area.
The picture resolutions range from 128 x 192 to 2048 x 3072 and all 5
resolutions are in 24-bit color. How big is image of the highest
resolution? It is around 20 megabytes in size. One can place between 100
- 150 images (PAC) on a MASTER Photo CD. Software is available on
computers that can convert these formats to a compatible graphic standard
(ie GIF, TIFF, TARGA, etc). The five picture formats that are included in
each image PAC are as follows:
Image Resolution
==========================
Base/16 = 128 x 192 pixels
Base/4 = 256 x 384 pixels
Base = 512 x 768 pixels
4Base = 1024 x 1536 pixels
16Base = 2048 x 3072 pixels
In image PAC is a compressed form that includes all 5 resolutions of a
single image and ranges from 4 to 6 megabytes on average. When used in a
program, the image is decompressed so that it can be displayed.
Stand-alone Photo CD players will play both standard audio CDs and display
Photo CD images on the television screen. Anyone will be able to enlarge
and manipulate the Photo CD images on a television to create custom Photo
CD albums with the players. Kodak's Photo CD players and Philips CD-I
players both work quite nicely.
For use with a CD-ROM on a computer system one needs to have the following:
- CD-ROM/XA (mode 2 from 1 sectors) and CD-BRIDGE format compatibility
- Display system (24-bit color is recommended for best results)
- Software driver that can read/access Photo CD discs.
In the future, Kodak Photo CD logos will be placed on compatible drives.
How is a photograph placed on a Photo CD?
- KODAK PCD Film Scanner digitizes 35-mm negatives or slides. The film is
scanned at a minimum resolution of 2048 x 3072. The three RGB values
(primary colors Red, Green, and Blue) are given 12-bits each for color
values.
- Image data is encoded and color adjustments are performed in addition to
compression. This is all done to achieve consistent, high quality
prints. The image color is reduced to 24-bits.
- The digitized image is then written to a Photo CD disc. It is written to
disc via CD-Writer device.
/**** A Graphical view of the Kodak Photo CD Finishing Process ****/
PCD = Photo CD
[ EXPOSED FILM ]
|
|
[ FILM PROCESS ] -> [ PRINTER/PAPER PROCESS ]
| |
| |
[Negatives (or Slides)] [ CONSUMER PRINTS]
|
|
[KODAK PCD Film Scanner]
|
|
[KODAK PCD Data Manager (computer)] -> [KODAK PCD Printer]
| |
| |
[KODAK PCD WRITER ] [KODAK Index Print]
|
|
|
[ Kodak Photo CD disc ]
|
|-------|------------------------------------|
| |
| |
| |
Home TV Viewing Personal Compututing
| |
| |
[Kodak Photo CD Player] [CD-ROM (XA, Multi-Session) ]
One can find out more information on Photo CD by contacting
the Kodak Information Center (KIC).
--==-- J) What is multi-session and why is it important to Photo CD?
Multi-Session is the ability to read more than one table of contents. One
can think of a book when thinking of table of contents. A single session
drive can only read one session. This is similar to a 10 chapter book and
only being able to read the first chapter. With multi-session, one can
read all sessions that were written at different times. If this were a
book you would be able to read all 10 chapters.
The advantage of multi-session is being able to place photographs taken at
different times. For example if one takes pictures during summer vacation
they can be placed on a Photo CD disc. At Christmas time you take more
pictures and they can be added to the disc as well. Every time one adds a
new set of pictures to a disc it is called a session. So one can see what
a useful feature Multi-Session capability is.
NOTE: Multi-Session works with all forms of CD-ROM data including Kodak's
Photo CD. So having multi-session one is not limited to the types of
data that can be added to the disc later on.
--==-- K) Interview with Scott Brownstein - Manager Advanced Projects at
Kodak (summary of the interview)
AD = Albert Dayes
SB = Scott Brownstein
AD: How long was the development process for Photo CD?
SB: Approximately 5 years.
AD: Ending in January 1992?
SB: Yes
AD: What computer was used for the development of Photo CD?
SB: Many different types ranging from MACs to VAX clusters to
Sun SPARCstations, etc.
AD: There are currently only 5 formats for Photo CD including
Master, PRO, Catalog, Medical and Portfolio.
NOTE: a general overview of the different formats was not part
of the interview.
MASTER format has a pac format with 5 different resolutions and can
store about 100 to 150 images.
PRO format which has higher resolution and supports larger film
formats other than 35-mm. These include 70mm, 120mm and 4 x 5 inch,
etc.
CATALOG format has low resolution than base images and can contain up
to 6000 images.
MEDICAL format is for storing CT (Computed Tomography) and MRI
(Magnetic Resonance Imaging) pictures in addition to standard film
formats. It can also be used for other diagnostic scans like
Ultrasound, PET (Positron Emission Tomographic) and Angiogram.
PORTFOLIO format allows the mixing of images, text and audio and
branching capability, all on one disc. These images are base
resolution.
END NOTE:
AD: How does the Catalog format work?
SB: It contains about 800 video pages and each page can have multiple
images on it. Each image has an index and can be used to present a
presentation. Using indexes and branching one can generate a unique
presentation.
Using Kodak's Shoebox software you can find any image by using a
keyword search. The Shoebox software works with smaller storage
requirements all the way up to very large jukeboxes with a capability
of over 100 Photo CD discs on-line at one time.
AD: And the Portfolio?
SB: It allows for the mixing of text, audio and images and Kodak will have
authoring tools out in 1993. The audio in this case can be either CD
audio (Red Book) or ADPCM. The branching is just an access method and
in this case interactive programmed access.
AD: What makes the PRO format different from the MASTER format?
SB: The PRO format can use film sizes larger than 35-mm and allows for a
max resolution of 8,000 x 12,000. It also has data encryption and
security features. For example watermarking. Each image can be given
its own unique key to effectively lock the image.
The watermark allows for the picture to display but have a message
across it like "PROOF" or "COPYRIGHT 1992", etc. So without knowing
the key this watermark will always be displayed on top of the image.
Once the person uses the correct key then the watermark will be
removed from the image being displayed.
AD: Are images scanned at 24-bit resolution?
SB: No, they are scanned at 12-bits per RGB (Red, Green and Blue values).
The software then compresses it to 24-bits.
The 24-bits is actually made up of 8-bits for luminance and the rest
for chroma.
AD: What is Kodak's Picture Exchange?
SB: Basically it allows people to store images on a consignment basis.
The fees are based on storage, referral and cross platform.
AD: How does one access Kodak's Picture Exchange?
SB: Anything with 9.6 (9600 baud) and higher can have access.
AD: What has been the response to Photo CD?
SB: It has been extremely positive. Having cross platform capability and
ISO-9660 helps quite a bit. In addition it reaches both the low and
the high end with the same technology. Also with Kodak providing
automatic scanning equipment speeds up the process of translating film
to Photo CD discs.
AD: What about multi-session? Are all of Kodak's Photo CD players
multi-session?
SB: Yes all Kodak's Photo CD players are multi-session and so are CD-I
players. The newer CD-ROM drives are also getting that capability as
well. In addition they can all play regular audio CDs.
AD: What about CD-WO and multi-session?
SB: This entire area of CD technology is very exciting. So instead of
being stuck with a 100 megabyte CD you can now add to it. One can add
any type of data because of multi-session technology. Since there is
no blank spaces between the data after the drive reads it, it will
think that it has just a larger CD-ROM. Normal CD-audio will not work
since it is not part of the specification. It is a problem with audio
CDs needing TOCs. But if the audio is recorded in the first session it
will be fine.
The advantage of this technology is 1) it is WRITABLE and 2) it is
PRESSABLE. Consider the low cost of floppy disks but then think of
long it takes to write data to one. Once you have a CD you can just
have them pressed. The average time to press a CD is about 4 to 6
seconds or approximately 100 megabytes per second. It makes perfect
distribution and duplication sense. With a recordable CD it is almost
the same as having a 600 megabyte floppy.
AD: What is the most important aspect of Kodak Photo CD technology?
SB: Actually there are three things:
a) cross platform
b) digital audio and digital video
c) high end (PRO market) and low end (Consumer market)
AD: Thank you
--==-- L) Which is the best CD-ROM drive to buy?
First thing it must be a SCSI CD-ROM drive! If you just want to read data
disks you can buy one of the older generation drives. Make sure that the
maker of the driver software has tested your drive so you will not be
stuck when it doesn't work. In this case contact ICD or Atari. Also if you
need Photo CD compatibility you need one that is both multi-session and
CD-ROM/XA compatible. Most of these new drives are either just becoming
available or will be coming out in early 1993. Price range is under $800.
The drivers for regular CD-ROMs are available from Atari and ICD. One
should contact either of the two companies for additional information.
At COMDEX, in the Atari Booth the CD-ROM drive being used for Photo CD was
a Toshiba TXM3301B1. This is a single-session model and software at the
time was only single session.
Currently the software only supports MULTI-SESSION on the TT030 and Atari
Falcon030, and only SINGLE session on the ST. It is a possibility that
multi-session capability will work on the ST in the future. Michael
Bernards wrote the driver software for Photo CD on the Atari and Calamus
SL (DTP) Photo CD access software.
Calamus SL has an Photo CD importer that supports all five resolutions of
an image.
One should contact the references given below for additional information
on availability of the Photo CD drivers. Kodak certifies CD-ROM drives
that are compatible with Photo CD as well. The best method is to ask on an
on-line service and consult magazines or call the Kodak Information
Center. Also consult with the maker of driver software since they usually
have a compatibility list of drives they have tested as well.
Toshiba, Pioneer, Sony and other have stated they will have CD-ROM drives
that will support CD-ROM/XA, multi-session and Photo CD.
The current CD-ROM/XA, multi-session Photo CD compatible drive from
Toshiba is TXM3301E1. This one is the only one currently shipping.
Upgrades from earlier versions of the TXM3301 are possible (depending on
serial number) contact Toshiba for more information.
The year 1993 is not only the year of the Atari Falcon030 but the year of
the CD-ROM/XA multi-session CD-ROM drives. Many will be coming out all
during the 1993 year and prices are dropping!
RECOMMENDATION: Buy a CD-ROM/XA multi-session SCSI drive. The cost is not
that much higher than normal SCSI drives and you will be
able to enjoy a long future with Photo CD and CD-ROM.
Summary:
For general use:
1) SCSI CD-ROM drive (external)*
2) SCSI host adapter (TT030 and Atari Falcon030 have built in SCSI ports.
The ST family requires SCSI host adapters like
ICD).
3) SCSI driver software that supports CD-ROM drives. **
4) SCSI cables and power cables as needed.
For multi-session, and Photo CD support:
1) SCSI CD-ROM/XA, multi-session and Photo CD (external)*
2) SCSI host adapter (TT030 and Atari Falcon030 have built in SCSI ports.
The ST family requires SCSI host adapters like
ICD). ****
3) SCSI driver software that supports CD-ROM drives. **
4) SCSI driver software for Photo CD support.***
5) SCSI cables and power cables as needed.
- Internal drives are possible but require additional work. Contact your
dealer for more information.
- * Be sure your CD-ROM drive has been tested with CD-ROM driver software
before purchasing one.
- ** Be sure your CD-ROM drive has been tested with both the CD-ROM driver
software and Photo CD software before purchasing one.
- *** The Photo CD software driver for the ST is currently single session
only.
/*********************************************************************/
CONTACTS for ATARI related CD-ROM and PHOTO CD products.
Atari Corporation
1196 Borregas Ave.
P.O.Box 61657
Sunnyvale, CA 94088
USA
(408) 745-2000
They also can be contacted on GEnie.
Products: MetaDOS, CD-ROM drivers, Photo CD drivers, Developer
information, Photo CD developers' kit
Beckemeyer Development Tools
P.O.Box 21575
Oakland, CA 94620
(510) 530-9637
(510) 530-0451 (fax)
Products: Hard disk backup, optimization software, SCSI Tape backup
software
ICD
1220 Rock Street
Rockford, IL 61101-1437
USA
(800) 373-7700 (orders)
(815) 968-2228
(815) 968-6888 fax
COMPUSERVE: Atari Vendors forum (GO ATARIVEN)
GENIE: ICD RoundTable
Products: SCSI Host Adapters, SCSI Driver Software and CD-ROM driver
software
DMC PUBLISHING
2800 John Street, Suite 10
Markham, Ontario L3R 0E2
CANADA
(416) 479-1880
(416) 479-1882 (fax)
(was ISD Marketing at one time)
GEnie: ISD
COMPUSERVE: Atari Vendors forum (GO ATARIVEN)
DELPHI: ISDMARKETING
Products: Photo CD importer for Calamus SL (DTP) supporting all 5
resolutions.
Oregon Research Associates
16200 S.W. Pacific Highway, Suite 162
Tigard, OR 97224
(503) 620-4919
(503) 639-6182 (fax)
GEnie: ORA.TECH
Products: Hard disk backup and optimization software, SCSI Tape backup
software
/*************************************************************************/
ISO-9660 filesystem made EASY
This is a very simple filesystem and it very easy to understand. The first
thing that happens it sector #16 is read. It then checks for the primary
volume descriptor.
____
1-2-3-4-5-6-7-8-9-10-11-12-13-14-15- |16| <----------
---- |
|
|
|
|
Check sector 16 for a Primary Volume Descriptor ------
If Sector 16 contains the Primary Volume Descriptor then jump to the root
directory. The root directory is given as an absolute sector number within
the primary volume descriptor.
PRIMARY_VOLUME_DESCRIPTOR
{
ID = "CD001";
other information;
location of root directory on the disc; ----
size of root directory; |
other information; |
} |
|
|
|
|
ROOT DIRECTORY <-------------------------------
The root directory contains the list of files and sub-directories. All
files and directories on an ISO-9660 CD-ROM are called directory records.
Here is an example of a root directory:
file_1.txt;1 <----- file
file_2.doc;3 <------------- file
sub_dir.;2 <----- sub directory
If we want to examine file_1.txt;1 and we read the directory record. The
directory record indicates what sector (absolute) that the file starts on
and how long the file is in bytes.
FILE_1.TXT;1
{
other information;
location of file on the disc;-----------------
size of the file (in bytes or characters); |
} |
|
|
|
|
data for the file <------------------------------
Now suppose we want to go to the sub-directory named sub_dir.;2
SUB_DIR.;2
{
other information;
location of sub directory on the disc;-----------------
size of the sub directory (in bytes or characters); |
} |
|
|
data for sub directory <----------------------------------
The data for this sub-directory is different than the file. The data is a
list of all the files and sub directories in the directory. The size of
this sub-directory is given by its length in bytes.
An example of the data in the sub-directory;
. <---- current sub-directory
.. <---- parent directory of this sub-directory named sub_dir.;2
file_99.doc;1
To read the file_99.doc;1 one uses the same method out-lined earlier to
get to file_1.txt;1.
The question is now how do we get back to the parent directory? We read
the ".." directory record. Then jump to the location (absolute) sector of
the current directory's parent which in this case is the root directory.
..
{
other information;
location of parent directory; ----|
size of parent directory; |
} |
|
|
parent directory data <---------------
The parent directory is read and its contents displayed. In this case the
parent directory is the root directory.
file_1.txt;1 <----- file
file_2.doc;3 <------------- file
sub_dir.;2 <----- sub directory
We are back to where we started again. It is not very hard to follow it at
all. It very similar to the filesystem in our Atari and IBM PC computers,
you might have noticed.
The filenames and sub-directory names look strange. Basically the
filenames are the same type as on the Atari. Its 8.3 format (for example
ATARI456.DOC) is very familiar. There is some extra characters on the end
and they add a version number. For example on some computers like
Digital's VAX every time you save the file the version number is updated.
For Example:
file.dat;1
save the file again
file.dat;2 <----- version number is updated after the file is saved.
Other than a few small things, ISO-9660 and the Atari filesystem are very
similar. As one can see the ISO-9660 CD-ROM filesystem is even simpler
than the normal Atari filesystems. For more technical details on the
ISO-9660 standard one needs to buy the ISO-9660 specification since it is
copyrighted by ISO.
/*********************************************************************/
MULTI-SESSION made EASY
When the CD-ROM drive first spins up it checks for the presence of a TOC
(table of contents) on the CD. This gives information about how big the
disc is in general terms. The first TOC is always in the same location so
all CD-ROM drives and Audio CD players check for its presence everytime
they are turned on.
With Multi-Session the entire disc has to be checked to see if more than
one session exists. The disc has a beginning and ending for each session
on the disc. So on a multi-session disc there will be several TOCs and
beginning and ending sections one for each session. The beginning and
ending sections are usually referred to lead in and lead out.
LI = (lead in) beginning
LO = (lead out) end
TOC = Table Of Contents (which is actually part of the lead in section)
/*-------------------------------------------------------------------*/
SINGLE session disc:
LI-TOC-INFORMATION-LO
/*--------------------------------------------------------------------*/
MULTI-session disc:
LI-TOC-INFORMATION-LO (session 1)
LI-TOC-INFORMATION-LO (session 2)
LI-TOC-INFORMATION-LO (session 3)
LI-TOC-INFORMATION-LO (session 4)
.
.
LI-TOC-INFORMATION-LO (session n)
/*-------------------------------------------------------------------*/
Who says CD-ROM/XA multi-session drives tell the truth?
The CD-ROM/XA multi-session drive looks at a disc and reads the first
Table Of Contents. The software driver asks if the CD-ROM/XA
multi-session drive has found the end yet. The CD-ROM drive lies and says
no and continues searching until it finds the last TOC on the disc. The
CD-ROM/XA multi-session drive replies with a YES when has found the last
session on the disc.
The best part about a multi-session is that one can add data at any time
whenever one needs to. It will be a great way to make updates to the
family album using a Photo CD disc as one's album. So many possibilities
and all available on the Atari too.
/************************************************************************/
Making My OWN CD-ROM made EASY
Walnut Creek provides a service to make a master CD-ROM for only $200.
They will take 600 megabytes on TAPE or floppies. Yes floppies disks are
accepted provided they are in MS-DOS format. Strange thing is Atari format
is the same as MS-DOS format. Does that give any one any ideas? <HINT,
HINT>
And with a Multi-Session CD-ROM/XA drive you can always add more data
later on to the disc.
/********************************************************************/
An Atari Dream CD-ROM
A dream CD-ROM for me would be to have all the articles in STart, ST-LOG,
ST-Applications, and Antic all on one CD-ROM. Just think all of those
articles and program listings in the palm of your hand.
It is not very fun searching through many STart magazines looking for that
great David Small article on the floppy disc controller (STart magazine
Fall 1987, I think?). All those great programming articles in one place...
WOW! A CD-ROM would be perfect.
Just think of being able to look up all past reviews from all the
different magazines in one place. A hint ... CD-ROM would be nice! Trying
to remember which magazine which they built a hard drive in... you could
search for it in seconds on a CD-ROM. Just think - complete text files and
Degas pictures for the diagrams too.
Remember something David Small said at one of his shows? "I want my
MAC-ST!" How about a new one.
"I WANT MY ATARI CD!!!"
/*********************************************************************/
GLOSSARY OF TERMS:
ADPCM = Adaptive Differential Pulse Code Modulation (audio that
allows compression) and is used in CD-ROM/XA.
AES = Audio Engineering Society
AIIM = Association for Information and Image Management
ANSI = American National Standards Institute
(sets industrial standards for the USA)
ATARI = Manufacturer of the World's Greatest Computers!
CD = CD or CD-DA is digital audio CD that we all enjoy listening
to. (RED BOOK) CD stands for Compact Disc. Stereo 16-bit
sound sampled at 44.1KHz.
CD-BRIDGE = Is an extension to CD-ROM/XA and is what Photo CD uses.
This allows for Photo CD discs to be played on CD-I
players as well. It adds additional information at the
track level of CD-ROM/XA track.
CD-I = CD-Interactive similar to CD-ROM and supports sound,
full motion video as well as data introduced by
Philips Corp. (GREEN BOOK)
CD-ROM = Based on audio CDs and is a read only medium and holds about
680 megabytes of information. (YELLOW BOOK)
CD-ROM/XA = CD-ROM eXtended Architecture is needed for Photo CDs. Special
information is added at the track level to give additional
features. This is a joint Philips, Sony and Microsoft
specification that deals with interleaving audio with data.
CD-R = A recordable CD. See CD-WO.
CD-WO = The disc can be written to many times but not erased. Tracks
are on the disc but data is not present. Data can be added
later on. (ORANGE BOOK part 2)
CHROMA = Color attributes, such as shade, saturation and hue.
CLIENT = In very general terms a "front end". Receives services
from the server. See server.
DISC IMAGE = An exact represent of bits that will be put on the CD-ROM.
This should not be confused with a graphic "image."
DRIVER = A series of instructions that is used to reformat the data
from a particular peripheral device to something the
computer can use. A printer driver is a good example.
EDC/ECC = Error Detection Code and Error Correction Code.
GREEN BOOK = The document which describes both disc format and
hardware specifications for Philips' proprietary CD-I
product.
HIGH SIERRA = (HS) the 1986 CD-ROM standard was superceeded by ISO-9660.
ISDN = Integrated Services Digital Network - basically allows for
voice, data and video to be used at the same time. This
could be said to be a vehicle for a single service that
supports all forms of signal traffic on a single platform.
ISO = International Organization for Standardization
(70+ standard organizations in different countries are
involved)
ISO-9660 = This international standard specifies the filesystem on
CD-ROM discs. (ISO 9660, 1988)
LUMINANCE = Portions of composite video signal that control brightness.
MASTERING = The process of physically making a disc. The facility is
very similar to the clean room used in making computer
chips. A glass master is "cut" using a laser; one or more
negative nickel stampers are made; and those are used to
produce the many copies of the CD-ROM.
MO = Magnetic Optical drive is read/write (many times)
optical device. Also defined in the ORANGE book part I.
MULTI-SESSION = The ability to read more than one session on a disc.
Very important for Photo CD. (Orange Book Part 2)
NISO = National Information Standards Organization.
ORANGE BOOK = Describes Magnetic Optical Disks and CD-Write Once discs.
It also deals with Multi-Session as well.
PREMASTERING = The method to produce a CD-ROM before sending it to a
mastering facility. This usually includes making the
ISO-9660 filesystem, adding error checking and correcting
code and making an image and then transferring the disc
image to tape.
PHOTO CD = Kodak's standard for storing pictures on CD-ROM discs.
POSIX = Formal description of one form of operating system of which
UNIX is an example. Many parts of UNIX are POSIX compatible
but not all of UNIX. POSIX specifics specific functions
that are part of the standard.
RED BOOK = CD audio standard introduced by Philips and Sony
ROCK RIDGE = Based on the fictional town in the movie "Blazing Saddles"
is an extension to ISO-9660 that allows for all the
special features in the UNIX filesystem to be used. Discs
formatted with Rock Ridge extensions can still be read
with any ISO-9660 driver.
SCSI = Small Computer System Interface (ANSI X3.31, 1986) allows
up to 7 devices (printers, hard disks, scanners, optical
drives, CD-ROM drives, networking cards and more) to a single
interface card.
SERVER = In very general terms... "back end" (provides services to
a client). Usually thought of in a client-server type of
relationship. File server, printer server are good examples.
SGML = Standard Generalized Markup Language - provides a system
for tagging text structures with generic identifiers
which mark the category or class to which a piece of
text belongs. (ISO 8879, 1986)
SINGLE SESSION = The ability to read one TOC (table of contents) or one
session. All CD-ROM drives generally fall into this
category. Usually made in reference to Photo CD.
TOC = Table of Contents (similar to the table of contents found
in a book). All CDs have one or more of them. This also
gives information on where the tracks start.
UNIX = An operating system created by AT&T Bell Laboratories in 1971.
It has become a very popular operating system and it runs on
many different platforms. Unix International (UI) and
USL (Unix System Laboratories) are in charge of promoting
and enhancing the UNIX standard.
WORM = Write Once Read Many device. You can only write to one
area on the disc once but you can read it many, many times.
The data that has been written can never be overwritten.
YELLOW BOOK = CD-ROM standard like the red book also by Sony and Philips.
/********************************************************************/
CD-ROM Drive manufacturers (not a complete list)
Chinon America, Inc
615 Hawaii Avenue
Torrance, CA 90503
USA
(800)-441-0222
(310)-533-0274
Hitachi Home Electronics
401 West Artesia Blvd
Compton, CA 90220
USA
(800)-369-0422
(310)-537-3766
NEC Technologies
1255 Michael Drive
Wood Dale, IL 60191
USA
(800)-366-0476
(800)-FONE-NEC
(708)-860-9500
Panasonic Communications
Two Panasonic Way
Secaucus, NJ 07904
USA
(800)-742-8086
(201)-348-7000
Philips Consumer Electronics
1 Philips Drive
Knoxville, TN 37914
USA
(615) 475-8869
Pioneer Communications of America
600 E. Cresent Ave
Upper Saddle River, NJ 07458
USA
(800)-527-3766
(201)-348-7000
Sony Corp of America
655 River Oaks Pkwy
San Jose, CA 95134
USA
(800)-352-7669
(408)-432-0190
(408) 434-6644
Texel
1605 Wyatt Drive
Santa Clara, CA 95054
USA
(800)-886-3935
(408)-980-1838
Toshiba America Information Systems
9740 Irvine Blvd
Irvine CA 92718
USA
(800)-456-DISK
(714) 455-0407
(714)-538-3000
(714) 583-3129 (upgrade info)
/*********************************************************************/
Sources for the standards and general information:
Audio Engineering Society (AES)
60 East 42nd Street
New York, NY 10165-2520
USA
Association for Information and Image Management (AIIM)
1100 Wayne Avenue, Suite 1100
Silver Spring, MD 20910
USA
(301)-587-8202
A professional association dedicated to document and information
automation and imaging. Includes applications of micrographics, optical,
and computer technology and systems for the information professional.
American CD-I Association
11111 Santa Monica, Suite 750
Los Angeles, CA 90025
USA
(213)-444-6619
Green Book or CD-I information
American National Standards Institute
11 West 42nd Street
New York, NY 10036
USA
212-642-4900
ANSI specifications
CD-ROM Professional Magazine
462 Danbury Road
Wilton, CT 06897
(800)-248-8466
This is a very good magazine for anyone in the CD-ROM business.
COMPUSERVE
5000 Arlington Centre Blvd
Columbus, Ohio, 43220
USA
(800)-848-8990
(614)-457-8650
ATARIPRO forum: (GO ATARIPRO)
file(s): SCSI specifications I and II (working specifications and not the
official which are only available from ANSI, ISO or Global
Engineering Documents).
CD-ROM forum: (GO CD-ROM)
file(s): Complete Rock Ridge specification, High Sierra specification,
CD-ROMF.ZIP, CDFAQ.TXT (frequently asked questions about CD-ROM),
and many other files. The other files deal with steps necessary
to make your own CD-ROMs, retrieval engines, CD-ROM related
periodicals, vendors (that sell CD-ROM discs), manufacturers
and CD-ROM consultants.
DR DOBBS JOURNAL forum (GO DDJFORMUM)
file(s): The C source for the December 1992 issue which has an article on
the ISO-9660 CD-ROM filesystem.
PHOTO forum (GO PHOTOFORUM)
section (5): Dedicated to Kodak's Photo CD
Dr. Dobb's Journal
411 Borel Ave
San Mateo, CA 94402
USA
(800)-688-3987
(415)-358-9500
A magazine dedicated to programming. The December 1992 issue had an
article called "INSIDE THE ISO-9660 FILESYSTEM FORMAT." Future articles
will cover Rock Ridge, CD-I, and CD-ROM/XA.
Eastman Kodak Company
Information Center
343 State Street
Rochester, NY 14650
USA
(800)-242-2424 ext. 53 - for information of Kodak Photo CD products
and compatible CD-ROM drives
ext. 36 - Locations to get Photo CD discs made
Kodak services, imaging, Photo CD, Photo CD compatibility information
GLOBAL ENGINEERING DOCUMENTS:
2805 McGraw Ave
Irvine, CA 92714
USA
(800)-854-7179
(714)-261-1455
(714)-261-7892 (fax)
More than a million documents. ISO specs and index, ANSI specs and index,
Engineering specs, Government standards, Software Standards and much, much
more. What don't they have?
Interactive Multimedia Association
3 Church Circle, Suite 800
Annapolis MD 21401-1933
USA
(410)-626-1380
(410)-263-0590 (fax)
High level membership actively working on technical standards for
cross-platform compatibility of authoring and delivery systems.
National Information Standards Organization (NISO)
PO Box 1056
Bethesda, MD 20827
USA
(301) 975-2814
A volunteer organization which develops ideas for a standard and then
passes it to standard organization like ANSI and ISO.
Optical Publishing Association
PO BOX 21268
Columbus, OH, 43221
USA
(614)-422-8805
(614)-442-8815 (fax)
OPA is the Optical Publishing Association, a non-profit trade and
professional group directed at helping publishers and all other players
build a digital publishing market. They also publish materials, including
a newsletter "Digital Publishing Business," and one can contact via
COMPUSERVE Rich Bowers of the OPA ( CIS id = [71333,1114] ) for more
information.
Prentice Hall
Englewood Cliffs, NJ 07632
USA
BOOK: SCSI: Understanding the Small Computer System Interface
by John Lohmeyer (Standards Architect, NCR Corporation)
Chairman X3T9.2 (scsi committee)
Discussion of SCSI-1, and a little on SCSI-2 and SCSI-3.
SCSI BBS ( operated by NCR corp )
USA
(719)-574-0424 (bbs)
Source for SCSI information and working specifications not the complete
specifications which must be bought from ANSI or GLOBAL ENGINEERING.
This includes SCSI-1, SCSI-2, and Fast SCSI, Wide SCSI and SCSI-3.
Tech Specialist
2601 Iowa
Lawrence, KS 66046
USA
(913)-841-1631
The May 1991 of Tech Specialist had several articles on CD-ROM.
a) "The ISO 9660 File System: A Reference Document"
b) "Designing A CD-ROM Retrieval System"
c) "Networking A CD-ROM drive"
Tech Specialist is published by R&D Publications which also publishes the
C USERS JOURNAL.
Walnut Creek CD-ROM
1547 Palos Verdes Mall, Suite 260
Walnut Creek, CA 94596
USA
(800)-786-9907
(510)-947-5996
(510)-947-1644
Pre-Mastering and Mastering Services, also sells usenet/internet archives
on CD-ROM. They will make you a master CD-ROM for $200 and up. Both
ISO-9660 and Rock Ridge formatting are supported.
CD-ROMs (CICA, Simtel20, Source Code, X11r5/GNU, C User's Group CD-ROM,
etc.)
------------------------------------------------------------------------
Microsoft MS-DOS CD-ROM Extensions 2.1
The format of the directory record for High Sierra discs is:
/* High Sierra directory entry structure */
typedef struct hsg_dir_entry {
uchar len_dr; /* length of this directory entry */
uchar XAR_len; /* length of XAR in LBN's */
ulong loc_extentI; /* LBN of data Intel format */
ulong loc_extentM; /* LBN of data Molorola format */
ulong data_lenI; /* length of file Intel format */
ulong data_lenM; /* length of file Motorola format */
uchar record_time[6];/* date and time */
uchar file_flags_hsg;/* 8 flags */
uchar reserved; /* reserved field */
uchar il_size; /* interleave size */
uchar il_skip; /* interleave skip factor */
ushort VSSNI; /* volume set sequence num Intel */
ushort VSSNM; /* volume set sequence num Motorola*/
uchar len_fi; /* length of name */
uchar file_id[...]; /* variable length name upto 32 chars */
uchar padding; /* optional padding if file_id is odd length*/
uchar sys_data[...] /* variable length system data */
} hsg_dir_entry;
The format of the directory record for ISO-9660 discs is:
/* ISO-9660 directory entry structure */
typedef struct iso_dir_entry {
uchar len_dr; /* length of this directory entry */
uchar XAR_len; /* length of XAR in LBN's */
ulong loc_extentI; /* LBN of data Intel format */
ulong loc_extentM; /* LBN of data Molorola format */
ulong data_lenI; /* length of file Intel format */
ulong data_lenM; /* length of file Motorola format */
uchar record_time[7];/* date and time */
uchar file_flags_iso;/* 8 flags */
uchar il_size; /* interleave size */
uchar il_skip; /* interleave skip factor */
ushort VSSNI; /* volume set sequence num Intel */
ushort VSSNM; /* volume set sequence num Motorola*/
uchar len_fi; /* length of name */
uchar file_id[...]; /* variable length name upto 32 chars */
uchar padding; /* optional padding if file_id is odd length*/
uchar sys_data[...] /* variable length system data */
} iso_dir_entry;
The difference between the two forms is the file flag byte moved to account
for an additional byte of date and time used for a Greenwich mean time
offset. See the May 28th draft of the High Sierra proposal or ISO-9660 for a
more complete explanation of the fields. Note that the C structs above are
not syntactically correct; C does not allow variable length arrays as struct
elements.
Choice of Filename Characters
On the first Microsoft Test CD-ROM disc, the Codeview demo failed because
certain filename characters that were legal on MS-DOS were not allowed
according to the High Sierra file format. When the software looked for file
'S1.@@@', it wasn't found because the character '@' is illegal for High
Sierra filenames and during High Sierra premastering, the file was renamed
'S1'.
Valid High Sierra filename characters are the letters 'A' through 'Z', the
digits '0' through '9', and the underscore character '_'. All other
characters are invalid. Note that the letters 'a' through 'z' are not
included so that High Sierra file names are not case sensitive. Under DOS,
filenames are mapped to upper case before they are looked up so this is
typically not a problem. When choosing file name characters, keep in mind
the restrictions of the file structure format and the operating systems your
media may be targeted towards.
Depth of Path
The High Sierra format allows for pathnames to be up to 8 levels deep. It's
possible to create a path on MS-DOS that is deeper than that but you won't
be able to transfer it to a CD-ROM.
\one\two\three\four\five\six\seven\eight\file.txt /* Ok */
\one\two\three\four\five\six\seven\eight\nine\file.txt /* Illegal */
Length of Path
The High Sierra format allows for the entire pathname to be a maximum of 255
characters. Since MS-DOS imposes a limit far lower than this, this should
not present a problem. The MS-DOS call to connect to a sub-directory is
limited to a directory string of 64 characters. The length of path
restriction is more a concern for Xenix/Unix than MS-DOS.
Amusingly enough, the MS-DOS call to create a sub-directory allows a
directory string greater than 64 characters which allows you to create sub-
directories that you cannot connect to.
Unfortunately, a CD-ROM may potentially contain a pathname that is much
larger than 64 characters long. This is not a concern here but is discussed
in a related memo - "MS-DOSifying your CD-ROM". As a rule, try to keep the
length of your longest path less than 64 characters and you should be pretty
safe.