The definition information for symptom substitution is provided by Stedman's. You can search our medical dictionary here. Stedman's, part of Lippincott Williams & Wilkins, provides a comprehensive line of health-science publications for healthcare professionals and medical students.
Gigabyte: A Gigabyte is approximately 1,000 Megabytes. A Gigabyte is still a very common term used these days when referring to disk space or drive storage. 1 Gigabyte of data is almost twice the amount of data that a CD-ROM can hold. But it's about one thousand times the capacity of a 3-1/2 floppy disk. 1 Gigabyte could hold the contents of about 10 yards of books on a shelf. 100 Gigabytes could hold the entire library floor of academic journals.
One byte is 8 bits. One Kilobyte is 1000 Bytes. One MegaByte is 1000 KiloBytes. One GigaByte is 1000 MegaBytes. One TerraByte is 1000 GigaBytes. In other words.. If you are talking about Memorychips with the capacity of 300 Gigabytes, that would be 307200 MegaBytes. If talking about HardDrive Capacity, then it would only be 300000 MegaBytes.