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D
| DAC | Digital to analogue converter |
| Data/Disk transfer rate | the speed at which data is transferred. Reflected in millions of bits per second (Mbits/second) |
| dB | decibel, a unit of measure that can be used to compare electrical power levels or sound wave intensities |
| Dedicated Servo | pre-recorded area on an otherwise unused part of the media dedicated to the servo |
| DMA | Direct Memory Access, a means of data transfer directly between the drive and the system memory without passing through the CPU |
| DOS | Disk Operating System, the master computer program that mediates between the application program and the PC user |
| DRAM | Dynamic RAM. DRAM is a direct accessible memory (RAM) where the information is usually stored in the form of charges in a capacitor, DRAM must be periodically refreshed, hence the name dynamic |
| Driver | software routing which receives Input/Output request from higher levels within the operating system and converts those requests to the protocol required by a specific hardware device |
| DVD (Digital Versatile Disc / Digital Video Disc) | an optical storage system. DVD media is the same in diameter as a CD-ROM disk but thicker, double-sided and able to store data on two layers |
