DVD-RAM (Book E of the DVD Forum) is a mixture of storage technologies from magneto optical (MO), phase change (PD and CD-RW), and even magnetic hard drives.

Tech

It use phase change as a recording material, "wobbled land and groove" recording method, embossed pits for header (addressing) information, Zoned Constant Linear Velocity (ZCLV) rotational control, and is a random-access, non-sequential medium.

Media

Media ,using a phase-change recording layer, can be either single-sided in a removable cartridge (2.6GB) or double-sided in a permanent cartridge (5.2GB).Future DVD-RAM discs may use a contrast enhancement layer and a thermal buffer layer to achieve higher density. Hitachi has announced reaching 4.7 billion bytes by reducing mark size from 0.41/0.43 microns to 0.28/0.30 microns and track pitch from 0.74 microns to 0.59 microns.The new DVD-RAM has a double-sided capacity of 9.4 gigabytes and is suitable for editing and accessing various multimedia information such as movies and music, it said. The new drive is compatible with current 2.6 gigabyte DVD-RAM discs, and is capable of reading other DVD and CD formats. Today prices are about $40 for 5.2 GB & $25 for 2.6 GB capacity disk.Media is available from Hitachi Maxell, Mitsubishi, Mitsui, and TDK.  Cartridge dimensions are 124.6mm x 135.5mm x 8.0mm.

Where we could possible read it?

One issue for DVD-RAM is that removing the media from the cartridge may compromise rewritability. And depending on the choices left to drive manufacturers, a DVD-RAM drive may or may not read CD-R, CD-RW, or PD.

DVD-RAM-compatible readers will require servos to handle switching between the lands and grooves. Also will need a decoder to handle scattered 32K ECC Blocks, something not needed for DVD-ROM and DVD+RW, since their blocks are continious.

Price

DVD-RAM is available from Toshiba, Hitachi, and Panasonic, are available in internal and external, SCSI and IDE models, and are priced between $500 and $700.