RISC World

The Next Technology CD ROM Drive

The first CD-ROM drives for RISC OS machines...

Whilst we take CD-ROM and DVD drives as standard these days it wasn't always so. Indeed it wasn't until 1994, when the RiscPC was released, that Acorn supplied a machine with a CD ROM drive as standard. Even then the CD drive was only available on the more expensive machines. CD technology itself had been developed in the late 1970s and early 1980s. The first commercial music CD was pressed on the 17th of August 1982. The format itself had been co-developed by Phillips and Sony with the intention of providing better and more compact music storage.

Unlike all previous methods of string music there was no mechanical contact between the mechanism and the medium itself. So CDs could "never" wear out, unlike tapes and records. Since the format was digital the aim was to remove hiss and other extraneous and unwanted noise from the music. By 1985 CD started appearing that had been produced digitally from start to finish. The method used to record the original performance was digital. All editing and production was done digitally and the final recording was digital. Hence the resulting music played back would be perfect and as intended by the artists. Early adopters of CD players may recall the launch of Dire Straits' Brothers In Arms CD, one of the first DDD (all digital) music CDs to be released.

The format for storing music on a CD was called "Red Book" and had been presented in 1980. The delay between the establishment of the standard and the release of retail CD players was caused by some unforseen problems. Whilst the data on the CD might be digital there were still "analogue" problems that needed to be resolved. For example, discs that didn't spin perfectly true, dust, dirt and even fingerprints. All these introduced noise into the system and forced the developers to come up with some clever methods for "error correction". You may be surprised to know that without such error correction and the clever storage for data defined in the Red Book a CD would have as much, or perhaps even more, hiss than an old cassette tape.

Having resolved the problems of making sure the data could be read accurately from the CD, or that the CD player could accurately "guess" any missing information, the two partners had a "modern" storage system. Having designed CDs to hold music thought then turned to what else they could be used for. The result was the development of the "Yellow Book" standard for storing all sorts of digital data. The problems of accurately storing and retrieving information had been solved, now what could be done with the new format?

In the late 1980's CD ROM drives for computers first appeared. Up until this point PC applications had been supplied on floppy discs. Does anyone remember installing Windows 3.1 from several floppies? The new format with it's huge storage potential was ideally matched to the developing computer industry. Acorn enthusiasts had to wait until 1990 before they could join the CD-ROM revolution. Even then it was at a price.

In 1990 Mike Williams reviewed the Next Technology CD ROM drive for the Archimedes, the first CD drive that could be used with RISC OS...

Next Technology's CD ROM for the Archimedes

Mike Williams previews the latest innovation for the Archimedes in the form of a CD-ROM from Next Technology.

The latest technology to impact on the computer scene is in the area of multi-media systems, and the Archimedes with its sheer power and high performance graphics is ideally placed to exploit such systems. Acorn has already made one foray into this market with interactive video (the Doomsday project), which was perhaps ahead of its time as well as being too expensive to be widely affordable. The latest venture is a collaboration with Cambridge based Next Technology which has developed a CD-ROM unit for the Archimedes.

The Next Technology CD-ROM unit should be available by the time you read this. Our preview is based on experiences with a development system running on pre-release software. But first of all, what is CD-ROM?

Everyone is more or less familiar with audio CD (standing for Compact Disc), small digitally recorded discs read by laser, and claimed to give greater clarity in hi-fi sound than conventional vinyl records. CD-ROM uses the same basic technology to record data (which can replace or supplement audio) on CD. With suitable software, a computer can then read all this information. CD-ROM currently has a capacity of some 600 MBytes - that's equivalent to some 250,000 pages of text, 5000 photographs, 72 minutes of high quality audio, or a combination of all three. However, CDs are read-only, hence the term CD-ROM (CD Read Only Memory).

Next Technology has developed a CD-ROM unit, capable of reading CD-ROMs and feeding the data into the Archimedes. Any audio is output separately, and can be directed to the Archimedes monitor's built in speaker(s), or to any hi-fi amplifier and speaker system. Sensibly, Next has adopted the standard ISO 9660 format (itself derived from the earlier High Sierra standard). This means that the Archimedes can access all other CD-ROMs produced to this standard, and several hundred already exist in the PC world. Next has also produced the software to access CD-ROM in the form of the CDFS (CD Filing System). This is fully compatible with all other Archimedes filing systems.

The Next CD-ROM unit consists of a flat box which sits easily on top of a 400/1 series machine and under the monitor (though it can be used with any Archimedes including an A3000), and is connected to the host system via a SCSI interface (supplied as part of the system). This means that as many as 28 CD-ROM units may be connected via the one SCSI interface providing some 17 gigabytes of information! The data transfer rate is of the order of 150K bytes per second with an average access time of 0.4 seconds. CDs must be enclosed in a protective case or caddy (one is supplied with a sample CD-ROM) for insertion into the CD-ROM unit.

The CDFS icon will appear on the icon bar as a filing system (though this had not been fully implemented on the development system). Clicking on the drive icon, as with any filing system, will open a window to show the contents of the CD-ROM. Using a clip-art CE produced for PCs, opening any of the top level directories revealed hundreds of picture files (in TIFF format). Using the program ChangeFSI (see RISC User Volume 2 Issue 10) it was a trivial matter to select any picture and convert it into an Archimedes sprite (it is likely that the ChangeSFI program will be supplied with the CD-ROM unit, as it can convert a wide variety of screen formats into equivalent Archimedes sprites).

This illustrates one application of CD-ROM, with its huge storage capacity, as a resource system. An Archimedes with CD-ROM unit can be readily connected to an Econet network, allowing the CD-ROM unit to be accessed by all network users, including those with a BBC model B or Master series computer! Because of the way it is implemented, it would be very easy to set up CD-ROM applications accessed using Genesis (see review in RISC User Volume 3 Issue 5).

The data on a CD can be anything (text, pictures, sound, animations etc). It is also possible to included programs, but most suppliers of CD-ROMs will more likely supply any software on a standard computer disc. That way, a CD-ROM can be used on any system; only the software needs customising. Hopefully, that will mean that the Archimedes, with its proprietary operating system RISC OS, will still be able to benefit from most of the CD-ROMs produced.

The CD-ROM unit can also play standard audio CDs, and thus perform as a very high quality CD player. As part of the system, users will be provided with the Audio Panel, window-based software for controlling the playing of audio CDs. This controls all normal functions, such as play, forward, reverse, next track, random play, continuous play etc, and you can also program the sequence in which tracks will be played, although there is no facility at present to save a programmed sequence. Thus Archimedes users buying a CD-ROM unit are also getting a fully fledged audio CD player, and one which can be playing as you use your Archimedes for other work.

Operation of all features is simplicity itself, relying as it does on standard Wimp and filing system conventions. Indeed, it is almost a disappointment that cataloguing a CD-ROM produces a directory viewer much like any other, but that in itself is the benefit of a standardised approach. The results, whether using data, or audio, are certainly impressive.

If schools or any other group want to create their own CD-ROM, then Next have the facilities to do this at a cost of between £200 and £300 per CD. Normally CDs are pressed from a high precision master (which costs £2000 to £3000). So-called recordable CD (also known as Write Once, Read Only) uses a layer of three metals which can be fused to create the CD data bits directly using a laser. The only problem in creating a full capacity CD-ROM is that the data will occupy some 800 floppy discs! However, Next also promises for the future a development system with a high capacity hard disc drive and nine track tape recorder (at a combined cost of the order of £8000).

At the moment, both data and audio can be placed on the same CD, but the controlling software must know the type of signal it expects to receive. Future developments include CD-ROM XA (extended architecture). With this, the decoding hardware can detect whether it is reading data or audio, separate the two and present two signals concurrently,-" offering the potential for simultaneous sound and data).

The CD-ROM unit will be marketed and supported by Next Technology, but discussions are taking place with Acorn and other software houses for the development of more CD-ROM based information. For the time being the combination of Archimedes and CD-ROM offers a power and versatility which few other systems are likely to match, certainly not at this price.

Product -   CD ROM Unit
        Supplier -   Next Technology Ltd.
St John's Innovation Centre
Cambridge CB4 4WS
Price -   £695 plus VAT including SCSI interface, all connecting leads, sample CD and documentation

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