The earliest CD-ROM drive appeared. 199 1 year, the multimedia PC working group in the software-publisher-association, which was joined by 1500 software manufacturers around the world, issued the first generation MPC (multimedia-personal-computer) specification, which promoted the popularization of CD-ROM publications. The capacity of an optical drive is 640MB, the data transmission rate of the optical drive is 150KB/S (designated as a single-speed optical drive by the International Electronics Industry Federation), and the average search time is 1 sec. With the continuous demand of the market, the hardware technology is also constantly improving. 1993, the second generation MPC specification came out, and the speed of optical drive doubled, the transmission rate reached 300KB/S, and the average search time was 400 ms

1In the summer of 995, the Multimdeia PC Working Group published the third generation of specifications and standards. Compatible CD formats include: CD-Audio, CD-Mode 1/2, CD-ROM/XA, photo-CD, CD-R, Video-CD, CD-I, etc. The reading speed has developed from 4 times speed to 24 times speed, 32 times speed and even 48 times speed, 50 times speed and 52 times speed. Among them, in the process of improving the reading speed, various manufacturers have adopted various methods to alleviate the problems of inaccurate positioning of the optical head and scratching the optical head due to excessive rotation speed. For example, NEC Company installed suspension damping rubber at four corners; Acer adopts suspension technology and rubber shock absorber bracket; Lite-on adopts suspension bearing technology; Asustek company adopts advanced dual dynamic suspension system, etc., which has stronger error correction rate, lower calorific value and tends to be perfect.

199565438+In February, five companies, including IBM, HP (Hewlett-Packard) and APPLE (Apple), called many manufacturers, such as SONY, HITACH and PIONEER, to jointly formulate a unified DVD specification and change the original digital video disk into the current Digital Versatile Disk. DVD is based on MPEG-2, and the storage capacity of each disc can reach more than 4.7GB (about 133 minutes of high compression ratio programs, including AC-3 5. 1 channel output decoding). DVD drives are also gradually developing from low speed to high speed. At present, the reading speed of DVD drive has reached 24 times.

Although the Blu-ray drive has been released and listed, with the appearance of the Internet, large-capacity memory cards, USB flash drives and mobile hard disks, and the price reduction, there are fewer and fewer people using CD-ROMs and DVD drives at present, especially CD-ROMs have been replaced by DVD drives, which are rarely used. Although Blu-ray drive can read 25G Blu-ray disc with larger capacity, it is not popular because of its high price and lack of competitiveness with U disk/memory card and mobile hard disk. Only a few film and television enthusiasts like to watch it.