Optical drives are specific to the types of disc formats they can read. For example, the earlier CD drives are unable to read DVD and Blu-ray discs. However, the newer the drive, the more formats it is likely to read. Thus, most Blu-ray drives can also read a number of DVD and CD formats in addition to the Blu-ray discs.
Earlier optical drives are generally connected directly to the motherboard via IDE cable. This has changed to the faster and more efficient SATA cable standard.