High Density CD Format Compromise Reached

by Dana Parker

September 15,1995

It's official, but it's not finished:

Today Philips Electronics NV announced that they have reached a compromise agreement on the format of high density CDs with the SD Alliance led by Toshiba Time-Warner.

The discs will use the 3M dual-layer single sided technology with the option of being double sided for higher capacities. The structure of the disc will be two .6 mm substrates bonded together. Capacity will be 4.7 GB per layer. The encoding will be Philips' EFM+, and the error-correction will be Toshiba's RSPC.

This is a true compromise, taking a little from each spec. Each disc will be comprised of two .6 discs bonded together in four different configurations. The first one is a single side of data glued to a blank disc, with 4.7 GB. The second is a dual-layer disc according to the 3M spec, 9.4 GB, with a blank second disc. The third, if still more capacity is need, is a dual-layer on one side, single layer on the other, and the fourth is the dual layer double sided disc. Reportedly all players will play any of these configurations, and the double sided discs will have to be flipped.

The specification is not yet completely finalized, but will be published within one month.

For updates on this story, link the DVD FAQ on this site.