A DVD-RAM is an optical disk that allows data to be read, written, and erased. It works like a floppy disk and allows users to run, copy, and delete files. The device offers all the benefits of a digital video disk (DVD), such as high capacity and compatibility with compact-disk (CD) formats, plus enhanced rewriteability. With current capacities of 2.6 Gbytes (single-sided) to 5.2 Gbytes (double-sided) per disk, a double-sided DVD-RAM disk provides more than eight times the storage of a rewriteable CD at a cost of less than $0.01 per megabyte. It also can read all CD and DVD formats, including CD-R, CD-RW, DVD-ROM, and DVD-R.
At the recent PC Expo in New York City, Hitachi Data Systems (Santa Clara, CA), Toshiba Storage Device Division (Irvine, CA), and Matsushita Electric/Panasonic (Secaucus, NJ) all introduced single-sided 4.7-Gbyte DVD-RAM drives and media. These disks achieve a higher storage capacity due to a decrease in track pitch and pit lengths. According to Toshiba, the transfer rate for a DVD-RAM is determined by the media specification. For example, 2.6-Gbyte disks offer a 1.385-Mbyte/s transfer rate, and 4.7-Gbyte disks offer a 2.77-Mbyte/s transfer rate.
At the trade show, featured demonstrations included the capturing of video from a DVD-RAM camcorder, writing digital content to a 4.7-Gbyte DVD-RAM, and then playing the contents on DVD-ROM drives, DVD players, and DVD recorders.
During another 4.7-Gbyte DVD-RAM demonstration, attendees viewed the playing of multiple MPEG full-motion videos from a DVD-RAM drive connected via a Universal Serial Bus (USB) Version 2.0-based, field-programmable gate array bridge. The bridge was developed by In-System Design (Boise, ID), a design and engineering firm specializing in USB bridging solutions. This bridge technology supports data-transfer rates to 60 Mbytes/s.
"DVD-RAM raises the bar in the storage and delivery of digital content and has the potential to overwhelm conventional input/output design," says Dana Berzin, marketing manager at Panasonic. "We are looking to companies such as In-System Design to make DVD-RAM technology more pervasive," he adds.
According to Alan Bell, director of IBM Research Division's digital media standards and commercialization group, currently available DVD formats are still incompatible. Because of this, the DVD Forum (Tokyo, Japan) used the PC Expo to announce a plan to prevent possible conflicts among DVD formats. The plan, called DVD Multi, is not a format; instead, it sets hardware specifications that enable disk compatibility for virtually all formats officially created by the DVD Forum.
