Phasewriter Dual
| Storage medium Phasewriter Dual (PD)
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 An open PD medium. The same sectoring as on a DVD-RAM or MOD can be seen on the surface . |
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| General | |
|---|---|
| Type | Optical storage medium |
| capacity | 650 MB |
| size | 12 cm (diameter) |
| origin | |
| developer | Panasonic |
| idea | 1995 |
| successor | DVD-RAM |
The Phasewriter Dual (PD) was the first generation of an optical storage solution based on phase change technology .
When phase Writer Dual there is no uniform spelling . Some also refer to it as a phase change disc because there is a plastic disc inside the cartridge. Other known synonyms of PD are the popular variants PD medium , PD disk (Engl. PD disk), PD cartridge or PD drive .
history
The PD was released by Panasonic in 1995 and was offered by the manufacturers NEC , Panasonic , Plasmon , TEAC and Toray .
Shortly after its publication, the PD was superseded by the CD-RW , which is also based on phase change technology. Although the PD is clearly superior to the CD-RW in terms of rewritability, data security and manageability, the CD-RW was sold more attractively and aggressively in terms of price. Another factor contributing to the rapid displacement of the PD was that many customers at the time were not aware of the difference between the operating concepts, writing to a CD-RW with burning software on the one hand and the removable hard drive-like use of a PD on the other.
The manufacturers tried from 1995 to 1998 to increase the market share of the PD with so-called combination drives. In addition to the PD, these combination drives could also read or write CD-ROM and CD-RW. Ultimately, the manufacturers' efforts were in vain. Since 2001, PD drives and their PD media have practically died out in the trade. The extinction of the PD happened silently because the drives of the first generation of DVD-RAM were backwards compatible with the PD.
Specification of the storage media
Only information that is of general interest is presented below. Pure technical details on more than 100 pages can be found in the chapter “Norms and standards” ( see below ).
The PD medium has a storage capacity of 650 MB (megabytes) and is only available in a cartridge . The actual data carrier is a plastic disc with a diameter of 120 mm. A PD medium can easily be confused with an MO medium or a DVD-RAM cartridge .
equipment
- Matsushita LF-1094 : PD / CD-ROM combo - drive from the very beginning (1995), SCSI
- TEAC PD-518E : A CD-ROM drive that could also read and write PD.
- Panasonic LF-D101, LF-D102, LF-D103 all three SCSI , as well as LF-D110 and LF-D111 both ATA : These five DVD-RAM drives of the first generation (DVD-RAM 1.0) could also read PD media and describe.
Norms and standards
- ISO / IEC 15485, based on the ECMA-240 standard .
literature
- Steinbrink, Bernd (1995): Light Bits. Phase change storage technology: a storage technology with a future. In: c't ISSN 0724-8679 , 12th year, issue 2, pages 76ff., Also available online for a fee . A good basic article that explains the history, especially the technique of the phase writer Dual in pictures.
