Over 100MB Removable Drives
Fight It Out: Magnetic vs Optical

100-Mbyte floppy disk drives are competing with 650-Mbyte optical disk drives. The Iomega 100-Mbyte FDD and CD-R drives are now in the lead.

Storage systems with removable disks and capacities of 100 Mbyte or more are beginning to be mounted in personal computers (PC) (Fig 1). The most sigificant difference they offer, in comparison to present-day floppy disks, is that they can easily store from megabytes to dozen megabytes of data being produced in this multimedia era.

At present, the most likely contenders are floppy disk drives (FDD) with capacities of 100 Mbytes and rewritable optical disk drives of 650 Mbytes. There are also removable hard disk cartridges, but they are thought unlikely to become standard equipment on PC's because the cartridge is thicker and heavier than floppy disk or CD-R disk.

 

100MB FDDs Lead Way

High-density FDDs appear to be winning the competition, with major PC manufacturers announcing adoption (Fig 2). In February 1996 Hewlett-Packard Co (HP) of the US announced it would mount the Zip drive from Iomega Corp of the US in one of its Pavilion home-use PC models. The company began shipment in April. The Zip drive has a capacity of 100 Mbytes, and according to the HP Home Products Division is "the standard storage device" in the US.

In March 1996, US-based Compaq Computer Corp announced a desktop PC with an internal LS-120 drive. The LS-120 is a 120-Mbyte FDD developed jointly with Imation Corp of the US, Matsushita-Kotobuki Electronics Industries Ltd of Japan, and OR Technology of the US.

Since May, a number of firms have announced adoption of the Zip drive, including Acer Inc of Taiwan, Packard Bell-NEC of the US, IBM Corp of the US and Unisys Corp of the US. All of them were trying out the new drives on a trial basis in selected models for the home and office. Acer put it in its US$500 PC, Packard Bell-NEC into PCs for both home and office markets, IBM into an Aptiva for home use, and Unisys into its Aquanta PC for the office. In Japan, Epson Hanbai Co, Ltd shipped a PC in March 1996 with a Zip drive.

 

Increased Optical FDDs

More and more PC manufacturers are also adding optical disk drives (Fig 2) to their products. In 1995, the only manufacturers offering optical drives were those trying to boost sales for their own drive systems. Matsushita Electric Industrial Co, Ltd of Japan mounted its 650-Mbyte phase-change optical disk drive, the PD, onto some home-use systems, while Fujitsu Ltd of Japan tried to achieve widespread sale of its 3.5-inch magneto-optical (MO) disk drive. In 1996, a number of other PC manufacturers also began offering internal optical drives. Compaq Computer and Epson Hanbai, for example, began shipping PC with internal PD drives.

Other manufacturers turned to the write-once compact disk-recordable (CD-R) drives. Gateway 2000 of the US already markets a PC mounting a CD-R drive as standard equipment, and Japan's industry leader NEC Corp is "considering it," says Hiromi Nakano, senior manager, Personal Computers Planning Department, Personal C&C Marketing Division. It could appear in some models as early as autumn.

 

Demand Picking Up

The PC manufacturers are divided when it comes to predicting which approach will become the standard. But they all agree that high-density removable drives are needed. The demand for high-density removable disk drives is higher than it has ever been before.

Since 1995, the removable disk drive market has expanded sharply (Fig 3). According to a survey by the Nomura Research Institute, Ltd of Japan, the market for rewritable removable disk drives increased from over a million units in 1994 to twice that in 1995. In 1996, they predict it will double again. Growth in the CD-R market is also explosive: a survey by Freeman Associates, Inc of the US puts the 1996 market size at 1.3 million units, six times larger than what it was in 1995.

 

More Demand from Floppies

One of the reasons demand for high-density removable disk dives is up is the wider range of applications for the PC (Fig 1).

It is becoming increasingly common to use a PC to create presentations, or download information from the Internet. With the widespread utilization of compact disk read-only memory (CD-ROM) and electronic still cameras, the PC environment can now easily handle images and relatively short video clips. The end user can, for the first time, handle multimedia data.

As a result, the file capacities handled by the user are rising, and files of a few megabytes or more are not at all unusual (Table 1).

When the data handled by the PC was primarily documents, floppy disks were fine. But 1.44-Mbyte capacity is simply too small to store multimedia data. A single file will not fit in a single disk, and this is what accelerated the appearance of high-density removable disk drives.

Some people feel that hard disks and networks are sufficient for storing and swapping data; others feel floppies are totally unnecessary today. However, HDD has a possibility of data destruction and networks do not connect with so many PCs. Furthermore, it takes much time to send megabytes of data over a phone line. There are, in short, many cases where a removable disk drive is needed.

 

Magnetic vs Optical

High-density FDD and optical disk drives are each trying to capture the position of "standard". The former is working to be installed in PCs as the successor to existing FDDs, while the later aims at replacing CD-ROM drives (Fig 4).

The question remains whether they can coexist ­ and most industry experts believe not, primarily because there is little difference between them in capacity. "If the user has one, he really doesn't need the other," sums up Paul Gottsegen, Director of Product Marketing, Commercial Desktop Division at Compaq.

High-density FDDs seem to be in the lead. FDDs were introduced to the market first and into volume shipment well before the optical drives. As a result they have become accepted as standard equipment. Removable drives will spread widely as their shipment volume rises. This is because more and more PCs will be able to swap disks.

 

Strategic Pricing

Manufacturers are hoping to ship millions of units of high-density FDDs in 1996 so they become the standard storage system. According to Iomega, cumulative shipment volume for the Zip drive will reach seven to eight million units this year. Track results like that simply cannot be ignored by the PC manufacturers.

The outstanding advantage of the high-density FDD is low price. The removable disk market really took off when Iomega announced an external drive for under US$200.

The original equipment manu-facturer (OEM) price for a high-density disk drive is probably under US$100 for a Zip drive, and US$150 for the LS-120. With an OEM price of a hundred dollars, it is more than likely that shipment volume will avalanche.

CD-ROM drives followed this course. According to survey firm Disk/Trend, Inc of the US, CD-ROM drive shipments were 2.53 million units in 1992, quadrupling to 11.07 million in 1993 (Fig 5). The average OEM price dropped from US$198 to US$111.

It will be quite some time before the price of a 650 Mbyte optical disk drive drops to this level. For the time being, manufacturers are aiming at US$200 and they don't expect to beat that target until the end of 1996 or early 1997. A US$100 price is even further down the road. In the meantime, it is clear that high-density FDD will continue to boost shipment volume.

 

100-MB Ample For Now

The weak point of high-density FDD is that they have lower density than that of optical disks, but most industry experts seem to agree this is not a major issue for the time being. "The 120-Mbyte LS-120 will eventually replace all floppy disk drives," predicts Compaq's Gottsegen. "The PD is for high-end use, and has far too much capacity for the general user."

The capacity depends on the PC applications. Most users are handling files with capacities up to dozens of Mbytes (Table 1). There are very few users that ever have to handle files with over 100 Mbytes in size.

The Zip drive, which holds the commanding position in the FDD market, has two problems. Firstly, it is only supplied by Iomega. Seiko Epson Corp of Japan manufactures Zip drives, but only as consigned production from Iomega. New comers are struggling to secure supports in the industry and establish competing products to Iomega. It is possible, however, that Iomega may change its policy.

Backward compatibility with existing 3.5-inch floppy disk drives is another problem. The Zip drive cannot read or write 3.5-inch floppy disks formatted to 1.44 Mbytes or 720 Kbytes. The two competing drive types offer backward compatibility, positioning it as a key feature to counter the Zip drive's lead.

 

Two Drives into 25.4mm

Iomega is attempting to solve the problem with a unit combining the Zip drive with an existing FDD. The unit manages to mount a Zip drive and a 3.5-inch floppy disk drive into the dimensions of a conventional 5.25-inch FDD and the firm is now developing a new unit which will mount both drives in the dimensions of a conventional 25.4mm thick 3.5-inch FDD. Iomega will ship a 15mm thick Zip drive beginning in January 1997, and plans to implement the new 3.5-inch drive by combining this thinner Zip model with a thinner FDD.

There are several problems with this approach, however. First, the 25.4mm mounting height is too large for notebook PC. Further, it costs considerably more than drives with downward compatibility, because it adds the cost of a Zip drive to the cost of a 3.5-inch FDD. Tadashi Hasegawa, manager, Engineering & Manu-facturing, Disk Drive Business Division, Mitsubishi Electric Corp of Japan, comments: "The Zip drive uses laser technology to read servo-tracking information, so that the optical component cost is added to the Zip drive. The optics are, however, as simple as those used in the simplest CD-ROM drives, and its function is cheaper than a thinner model of FDD (about US$30). When we consider downward compatibility, the LS-120 turns out to be cheaper than a sum price of a Zip drive and thinner FDD model." However, currently the sum of a Zip drive and existing thick 3.5-inch drive is cheaper than LS-120 price.

 

Performance, Compatibility

Downward compatibility generally makes it difficult to attain maximum performance.

The LS-120 provides downward compatibility by using an integrated magnetic head to handle both conventional floppy disk read/write processing and high-density floppy disk access. In both processing procedures, the head contacts the disk. Conventional floppies are designed for contact, and a contact design for the high-density disks also improve the drive's suitability for volume production. Disk speed is constant at 760 rpm.

With this technique, the performance with the high-density disk cannot be increased too much. This is because a faster disk speed for higher performance would lead to head flight and become impossible to assure normal drive operation.

The Zip drive discards downward compatibility and is designed to have a flying head, as used in hard disk drives. The speed is 2,945 rpm, which is significantly higher than the LS-120, and as a result the data transfer rate is higher and average latency shorter.

 

CD-ROM as an Extra

If the optical disk drive, on the other hand, can maintain compatibility with existing CD-ROM drives and drop the price to about the same level, they will be able to replace CD-ROM drives in the market and withstand competition from magnetic disk drives.

The CD-R drive is the most likely to succeed here, because disks written on a CD-R drive can be read on a conventional PC CD-ROM drive. Even if the CD-R drive itself does not become a widespread peripheral in the market, it will still be possible to easily distribute disks written with it.

Further, data written with CD-R will not become a wasted resource for quite some time, because the ability to read CD-ROM media will remain a standard function in PCs for the foreseeable future.

CD-ROM drive manufacturers today are finding it more and more difficult to add new value to their products, and it is certainly more than possible that they may all decide to jump on the CD-R manufacturing bandwagon. As a storage device engineer points out, "When you consider possible scenarios for high-density removable disk drives in the future, the CD-R is the most obvious result." NEC's Hiromi Nakano agrees: " At present, there is no other choice but CD-R. We hope to mount CD-R drives in PCs released in the second half of 1996."

 

Superiority in Data Swap

If the most important consideration is data compatibility with as many other PCs as possible, then the only answer is the CD-R.

The CD-E, expected to appear in early 1997, will be unable to be read on conventional CD-ROM drives. Optical disk drives normally use a laser beam reflection at the recording layer to extract the signals. The recording film of the CD-E, however, uses a different structure from that of the CD-ROM, to make possible rewriting. Reflectivity of the CD-E is only 20% lower, and because this is under the 70% specified in the CD-ROM standards, CD-ROM drives cannot pick up the signal. A special circuit will have to be added to CD-ROM drives to absorb the different reflectivity before they can play CD-E disks.

PD disks are mounted in special cartridges and cannot be inserted into conventional CD-ROM drives, and in any case their unique formatting makes it impossible to read them on anything except a PD drive. MO disk drives of 3.5-inch in size can read only 3.5-inch MO disks.

 

Right Recording Technique

It is much easier to use the new CD-R drives, thanks to a write technique called Packet Write and the development of a filing system that allows the PC to handle the CD-R as if it were a rewritable optical disk.

The conventional CD-R drive has been restricted by an inability to write data, and a formatting that only supported the ability to write data sequentially, such as for music. These restrictions made it difficult to use the CD-R as a storage system for PCs.

Take disk write, for example. Conventional CD-R used either "Disc at Once" recording (recording the entire disk at one shot) , or "Track at Once" recording, adding one track at a time like a music CD. And worse, only 99 tracks were added. The result, of course, is that the CD-R was impossible to use for writing many small files to, and so it ended up as a hard disk backup system where large volumes of data were written at once or as a way to make test CD-ROM media.

The practical application of Packet Write solved this restriction. Data is divided into packets of several dozen Kbytes each and can be appended a little at a time. In the spring of 1995 Sony Corp of Japan announced a Packet Write CD-R drive, followed by Ricoh Corp of Japan, which upgraded the firmware in its CD-R drive (first shipped in May 1996) to support Packet Write, and began shipping the new drive in July.



Handling Difficulty

With Packet Write, the CD-R drives can be handled just like a rewritable media. Sony developed its CD-R file system (CD-R FS) to do just this.

Driver software for the file system is installed into the PC operating system (OS), converting the logical addresses used by the OS to access data, into physical addresses (physical data locations on the disk), as shown in Fig 6. When the user specifies a data rewrite, 64-Kbyte packets are written to another location on the disk and the correlation with physical addressing is updated. For the OS, the CD-R looks just like a rewritable media.

PC users can now treat their CD-R drives just like floppy disks, storing files with OS-provided file management tools like the Windows 95 Explorer and the Macintosh Finder. When the correlation between the logical and physical addresses is broken, the file simply disappears.

 

by Takuji Imai and Mamoru Harada