CD-writer/DVD-rom combo

By "CD-writer", it means it can read and write CD-R and CR-RW discs.
By "DVD-rom", it means it can read DVD discs only.
By "combo", it means it can serve as "CD-writer" AND "DVD-rom".
Remark: In the old days, CD-writer and DVD-rom are two separate disc drives. As the technology improves, they can be combined into one single disc drives and save space.

讀 / 燒 CD 和 DVD 是用兩個不同的雷射頭的

2009-03-27 00:06:40 補充：
燒錄DVD和睇DVD碟是OK，但錄CD和睇CD或VCD就失敗，正正是因為它們用不同的雷射頭。壞了其中一個，另一個就仍然正常