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%% Compact Disc, How good is it ?                   by David Schofield %%
%%                                               schofieldd@newi.ac.uk %%
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At the moment, CD's are being touted as anything, and everything, from the 
next big thing in games playing, to the saviour of home computing. Every major
computer, and console, manufacturer has either released, or is currently
developing a CD based system. The question is, how useful actually are CD's ?


The History of Compact Disc.

CD's were first launched in the early 1980's by Philips, and over the rest 
of the decade, they slowly gained a foothold in the music market, where they 
were sold as vastly superior replacements for the old fashioned vinyl LP's and 
cassette tapes which were available at the time. The main reason for their
success in this market was the promise of better sound quality, and a vastly
superior lifetime.

However, from the start CD's have had their detractors. True audiophiles
argued that the sound quality on a digital CD could never be superior to an
analogue recording because of the quantisation of the sound. Also, CD's were
found to have a much shorter lifetime than anticipated, with some CD's
snapping on removal from the carrying case, and others reacting with sulphur 
residues in the cardboard packaging. Admittedly, the use of sulphur-free 
cardboard record sleeves to store the CD's are becoming more and more common.

It was not until the end of the decade that computer designers and users 
first started to realise the huge potential of CD's for information storage. In
fact, it was the early 1990's when the first CD-based machines hit the streets. 
The first two of these machines that the man on the street could hope to buy 
were the Philips CD-I, and the Commodore CD-TV, both of which were relative
failures at the time. Although Philips are still engaged in an active
advertising campaign, it is rumoured that this is because Philips was relying
on CD-I to succeed to secure financial stability.

However, as multimedia caught on in a large way, more and more machines had 
CD drives released for them, and the software designers started to write 
software which took advantage of the large storage available. The earliest 
programs were mostly of an educational bias, with dictionary's and 
encyclopaedia's highlighting the extraordinary potential of the new medium.


Software on Compact Disc.

The majority of early, and for that matter modern, CD games always appeared 
to consist of a slightly re-written version of an early non-CD success, with
extra music, and graphics padding out the CD. In fact, it is still difficult to 
name a single game which takes full advantage of the storage available.
However, this can be, at least partially, attributed to the high cost of
development.

There are two main game genres which could appear to benefit from the extra
storage presented by CD's, simulations, and graphics adventures. With graphic
adventures, the possiblities are endless; full stereo soundtrack, digitised
location graphics, large numbers of differing locations, and the complexity of
the solution are all factors which could be improved with the extra storage.
For simulations, the possibilities seem more restricted, but it is entirely
possible to have much more complex algorithms, resulting in even more realism
than is possible nowadays. Also, the use of digitised pictures in flight
simulations, and the ability to store many different weather conditions, would
lead to the possibility of full scale flight trainers available at home.

The majority of the best of the current CD software appears to belong to the
world of education. The possibilities presented by a multimedia encyclopaedia
are beyond anything which was available even five years ago. It should soon be 
possible to obtain CD's which contain full music scores, along with a full
biographiy of the composer. Already, it is possible to buy, with digitised
pictures, multimedia applications explaining how the body works, without having
to resort to dissection. This is, without a doubt, the main areas where the use
of CD's is without equal in any other storage format.

The possibilities for buisness software is also endless. It should soon be
possible to buy a CD based word processor, which combines the best features of
Word for Windows, WordWorth 3, Final Writer and Quark XPress, with a full
multilingual dictionary and thesaurus, a CD full of clip art and graphics, and,
one or more CD's, full of fonts. This is the kind of program which a large
number of people, myself included, would kill for.

One of the most exciting developments in the CD field is the release of Full
Motion Video, an amazing little gizmo, which allows the CD to store graphic
images using MPEG (Motion pictures something Group) compression. This allows
actual film footage to be played though a suitable unit. Although the
compression is currently only good enough to display images on a par with a VHS
video, it is hoped that within the next few years, broadcast standard images 
will be possible. Already, the first games are starting to take advantage of
this new technique, and several are available with state of the art live action
footage forming an integral part of the game. As well as incorporating this 
feature into games, it is possible to buy CD versions of various successful 
films, including Top Gun, and various music videos.


The Problems with Compact Disc.

At first glance, CD appears to be nearly perfect, however, on closer
consideration, the reality is slightly different. One of the golden rules of
life is that nothing is perfect, and CD is not the exception to this rule.

There are several major disadvantages with the use of CD, but the main problem
is with the non-availability of writeable-CD. As CD's can store so much data,
it is inconcievable that the average user will be able to make backup copies of
any program on CD. At first, this does not seem like a major problem, but CD's
are relatively easy to break, and how many companies would be willing to
replace a CD which was rendered unusable ?

A large number of home computer users buy a computer initially to play games,
but, after a while most progress onto others areas of interest. The potential
of advancement on a CD only system is very limited, for instance, who would
spend their time learning to program on a CD based machine if they were unable 
to save their programs. The same goes for the amateur musicians, and graphic
artists, who are not going to be able to show off their latest works. Also, the
market for professional developers will be severely curtailed, which could
result in a similar situation to that on the cartidge based games consoles,
where, to program software on the format, the majority of the required 
equipment needs to be licensed from the console manufacturers.

Even those who just use their computers as games machines are going to be
limited to the type of game that they can play. How many of the modern games
are completable in one session ? Games such as Frontier, The Secret of Monkey
Island, and other graphics adventures are especially limited by the lack of a
storage option for saved games. It would be theoretically possible to use a
password system within the game, but as games get more complex, the length of
password to be remembered will increase proportionally. Just imagine how long
the codes for Frontier would have to be ? With 1000 different starports, the
code would have to be 10 letters long, just for the location, and that is not
including other data, such as the current score, type of ship, and the cargo
carried.

At the moment, the average game can take anything from six months to two years 
to write, for a couple of floppies. Even though the basic code would remain the
same on a CD conversion, to add the extra graphics and sound required to show
the full potential of CD, it would take the skills of graphic designers,
musicians, actors, directors, and a full set of scriptwriters. Admittedly, 
digitising the pictures, and composing the music would take a shorter length of
time than writing the code for the program, but it would still take a 
considerably longer amount of time for development.

It is currently possible to manufacture a program onto CD than it is to make
the same program on floppy disk, but the software companies seem determined
to make a larger profit with the CD version. This is the same situation as the
music industry has been in for several years, and the monopolies commision (in
the UK) were, at one point, trying to force the manufacturers to reduce the
cost of a CD, but this appears to have had little effect.

Another potential problem with the rise in the popularity of CD's, is the
possibility of the death of the shareware and PD scenes. These both rely on the
ability of programmers to write software, and then, save it in a form so that
other people can access it. This required some form of portable storage media.


The Rivals in the Marketplace.

As a mass-storage medium, CD takes a lot of beating, but, there are other
available media which have advantages, and disadvantages, over CD.

The most common form of mass-storage device, is the hard disk, which forms an
integral part of the majority of new computers bought today. These come in a
variety of shapes and sizes, ranging from 20MB, up to 4.5GB, in a variety of
IDE, SCSI, 2.5", 3.5", and various other configurations. Hard drives currently
have a much faster access time than CD, as well as a far greater data transfer
rate, but, the vast majority are not portable.

Another common type of mass-storage device is the tape streamer, which uses a
high quality tape, similar to the ones found in DAT's. These also come in a
large variety of sizes, with a storage capacity ranging from several hundred 
MB's up to several GB's. The main advantage of tape streamers over hard disks
is that they are transportable, but, accessing data from a tape streamer is
almost an arcane ritual, with the tape having to be in the correct position to
find the data. It is for this reason that tape streamers are most often used as
backup devices for hard drives, and over similar storage systems.

One of the newest rivals to hit the marketplace is the floptical, which works
optically, like a CD, and, unlike a CD, it can be written to. The main
disadvantage with the floptical discs is cost, with the cost of a basic unit
costing up to ten times the cost of a CD drive (Power Computing floptical
#800-1000, Silica CDrom drive #99). However, floptical drives can be used to
store a large amount of data on a single disk, and, the cost of new disk is not
too prohibitive.


Q.E.D.

Compact discs are a truely remarkable form of computer media, but, along with
most other things in this life, they are nowhere near as perfect as the
salesmen expect you to believe. There are niches which CD could fill better
than any other rival computer media, but there are also niches where floppy,
and hard, discs will rule supreme for a long time to come, or, at least until 
the release of writeable CD's.